Céline Mahfouz

Elissar Gemayel

Anthony Ouba

Abed El

Rahman Hassoun

Ali Badereldinne

Laury Acaf

Aurore Assaker

Karine Hage

Maria Feghali

Rawa Fallah

The cartilaginous fishes of the Eastern Mediterranean: A literature review on the biology, ecology and geographic range of these species

Keywords: Chondrichthyans, conservation, distribution, life history, Lebanon, Levantine basin Life history traits, population structure, spatial and seasonal distribution, cartilaginous fish, Eastern Mediterranean Lebanon, length-weight, regressions, cartilaginous fish, fishing, elasmobranchs Chapter V: Population biology

and all whom I could not mention for their persistent support in all times

Résumé

Face à la pêche intensive des espèces marines de haut niveau trophique, l'instauration de mesures de gestion appropriées s'avère nécessaire. L'objectif de cette étude est de contribuer à une meilleure connaissance des poissons cartilagineux dans les eaux côtières libanaises de la Méditerranée orientale.

Après une introduction générale (chapitre I) introduisant le contexte et les objectifs de l'étude, vient la présentation du site d'étude et des diverses méthodes employées (collectes des données, mesures biologiques, analyses statistiques etc.) (chapitre II). Les données ont été collectées à partir de captures expérimentales dans le cadre du projet scientifique "CIHEAM PESCA-Libano" et d'observations périodiques des poissons capturés par les pêcheurs et présents dans les poissonneries.

Le chapitre III est dédié à une synthèse bibliographique sur la biologie, l'écologie et la répartition géographique des poissons cartilagineux de la Méditerranée orientale.

Dans une première partie du chapitre IV, l'accent a été mis sur les différents aspects de la distribution spatiale et saisonnière, la diversité, la biologie et l'écologie de ces espèces. Au total, 314 spécimens de poissons cartilagineux ont été échantillonnés appartenant à 25 espèces, dont 11 Over the past millennia, humans have deeply altered biodiversity on Earth and especially those of vertebrates (Schipper et al., 2008;Hoffmann et al., 2010). The largest habitats with the longest evolutionary history are found in Earth's oceans. There is a great worry for marine biodiversity (functional, specific, genetic, taxonomic, ecosystems diversity) due to increase of human impact [START_REF] Jackson | The future of the oceans past[END_REF]. Overfishing, habitat degradation and pollution have profoundly altered populations of marine animals [START_REF] Hutchings | Collapse and recovery of marine fishes[END_REF][START_REF] Lotze | Depletion, Degradation, and Recovery Potential of Estuaries and Coastal Seas[END_REF][START_REF] Polidoro | Patterns of extinction risk and threat for marine vertebrates and habitat-forming species in the Tropical Eastern Pacific[END_REF]. For example, the population of humpback whale, Megaptera novaeangliae (Borowski, 1781), was reduced to five percent of its previous level between 1920 and 1986 [START_REF] Butman | Whaling effects on deep-sea biodiversity[END_REF]. Overfishing can affect biological diversity as the species is no longer able to maintain their role as prey, predator, or competitor in the ecosystem when their populations are extremely declined, which can lead to ecological and functional extinction [START_REF] Lee | The effects of overfishing on marine biodiversity[END_REF].

Cartilaginous fish species have also undergone alterations in populations and are under several threats due to increase of fishing pressure and habitat loss [START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF][START_REF] Simpfendorfer | Results of a fisheryindependent survey for pelagic sharks in the western North Atlantic, 1977-1994[END_REF][START_REF] Dudley | Population status of 14 shark species caught in the protective gillnets off KwaZulu-Natal beaches, South Africa, 1978-2003[END_REF][START_REF] Ferretti | Patterns and ecosystem consequences of shark declines in the ocean[END_REF]. Similar to most marine ecosystems worldwide, the Mediterranean Sea is highly impacted by various threats [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF] including commercial, artisanal and recreational overfishing, aquaculture, overpopulation along the coasts, and many forms of pollution [START_REF] Mouillot | Protected and Threatened Components of Fish Biodiversity in the Mediterranean Sea[END_REF]. Climatic changes and species invasion are two additional threats this last century. Twenty percent of the Mediterranean chondrichthyans are considered threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. Therefore, light must be shed on this region in order to protect, manage and conserve the species of this fish class.

The Mediterranean Sea: Biodiversity, threats and fisheries

Geographical overview

The Mediterranean is the largest and deepest enclosed sea on Earth. It has narrow continental shelves and a large area of open water. It covers approximately 2,500,000 km 2 (excluding the Black Sea), representing around 0.2% of oceans volume, with an average depth of 1460 m and a maximum of 5267 m [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF] (Figure 1). It connects the three continents: Africa, Europe, and Asia. It is connected to the Atlantic Ocean in the west through the Strait of Gibraltar and to the Sea of Marmara and the Black Sea in the east through the Dardanelles. The Mediterranean has been artificially connected to the Red Sea and Indo-Pacific region through the building of the Suez Canal in 1869.

Figure 1: Map of the Mediterranean Sea and surrounding countries [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF].

The climate in the region is characterized by hot, dry summers and cool, humid winters. The annual mean sea surface temperature shows a high seasonality and important gradients from west to east and north to south [START_REF] Hopkins | Physics of the sea[END_REF]. The strong environmental gradients in the basin makes the eastern part more oligotrophic than the western one [START_REF] Azov | Eastern Mediterraneana Marine Desert?[END_REF]. The increase in temperature and salinity from north to south and from west to east causes the decrease in biological production in a likewise direction [START_REF] Danovaro | Exponential decline of deep-sea ecosystem functioning linked to benthic biodiversity loss[END_REF].

Biodiversity

The recent marine biota in the Mediterranean Sea is primarily derived from the Atlantic Ocean, but the wide range of climate and hydrology has contributed to the co-occurrence and survival of both temperate and subtropical organisms [START_REF] Bianchi | Marine biodiversity of the Mediterranean Sea: Situation, problems and prospects for future research[END_REF]. It is known for the diversity and high endemism of marine species (crabs and crayfish, mammals, and cartilaginous fish) [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. Up to 18% of the world's macroscopic marine species (out of which 25 to 30% are endemic) are found in the Mediterranean basin although it makes less than 1% of the global ocean surface, confirming an incredibly rich biodiversity for such a small area [START_REF] Bianchi | Marine biodiversity of the Mediterranean Sea: Situation, problems and prospects for future research[END_REF]. Currently, the Mediterranean Sea holds 17,000 (7%) of all known marine species [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. The level of endemism is especially high on the islands of the Mediterranean, where species have evolved to survive in very specific habitats [START_REF] Blondel | Biology and Wildlife of the Mediterranean Region[END_REF]. Around 23 of the world's cetacean species are found in the Mediterranean, consisting of 9 known year-round residents [START_REF] Reeves | The status and distribution of cetaceans in the Black Sea and Mediterranean Sea[END_REF]. This sea is also home to the most endangered pinniped: the Mediterranean Monk Seal Monachus monachus and it holds around 80 cartilaginous fish species, 40% of which are threatened [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF][START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF][START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF]. However, Mediterranean biodiversity has been and will be continuously altered and shaped by natural and anthropogenic factors in the past and the coming future [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF].

Threats

The effects of human activities are relatively stronger in the Mediterranean than in any other sea of the world [START_REF] Blondel | Biology and wildlife of the Mediterranean region[END_REF]. Its coasts are highly inhabited and the region strictly participates in the global economy and trade welcoming approximately 200 million tourists yearly [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF]. Its coastal ecosystems have been particularly affected by the past and recent human activities and economic development [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF][START_REF] Papadopoulou | The Mediterranean Sea: Additional information on status of threatened ecological characteristics relevant to the Marine Strategy Framework Directive[END_REF]. The knowledge about processes, ecological species distribution, the condition of its ecosystems and the drivers for biodiversity loss is still vague, even more than most of the basin is unmanaged and exposed to threats (Notarbartolo di [START_REF] Di Sciara | Identification of potential SPAMIs in Mediterranean Areas Beyond National Jurisdiction[END_REF]. Many of the ecological characteristics in the Mediterranean Sea are under threat with areas of potential high cumulative threats overcoming the western and eastern basins and fewer in the southeastern region [START_REF] Coll | The Mediterranean Sea under siege: spatial overlap between marine biodiversity, cumulative threats and marine reserves[END_REF]. The most important causes of current and future threats for the Mediterranean species are habitat loss and degradation, pollution, overexploitation (unsustainable aquaculture and fishing), eutrophication, maritime traffic, invasive alien species, human disturbance, climate change and bycatch [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF][START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF] (Figure 2). Moreover, temporal patterns indicate that overexploitation and habitat loss are the main human drivers of historical changes [START_REF] Lotze | Historical changes in marine resources, food-web structure and ecosystem functioning in the Adriatic Sea[END_REF]. The marine ecosystems and species in the Mediterranean Sea are affected by several of these threats. For instance, some cetaceans are severely affected by noise pollution (due to marine traffic) that impairs their ability to find prey, while others are affected by chemical pollutants such as polychlorinated biphenyls (PCBs) which affect the immune system, increasing sensitivity to illness, and causing increased mortality and reduced reproduction [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF].

Figure 2: The current and future threats for marine biodiversity in the Mediterranean [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF].

Furthermore, the southeastern region of the Mediterranean is also influenced by the introduction of Lessepsian (Indo-Pacific) species [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. In total, the number of Lessepsian species has reached more than 790 in the Mediterranean Sea, with some of the invaders through the Suez Canal having been very successful colonizers of Mediterranean marine ecosystems [START_REF] Galil | A sea change -Exotics in the Eastern Mediterranean Sea[END_REF][START_REF] Zenetos | Annotated list of marine alien species in the Mediterranean with records of the worst invasive species[END_REF][START_REF] Golani | Genetic bottlenecks and successful biological invasions: the case of a recent Lessepsian migrant[END_REF][START_REF] Golani | Colonization of the Mediterranean by Red Sea fishes via the Suez Canal-Lessepsian migration[END_REF][START_REF] Oral | Alien fish species in the Mediterranean-Black Sea basin[END_REF].

One example is the silver-cheeked toadfish, Lagocephalus sceleratus which is causing several problems in the surrounding ecosystem and fisheries sector [START_REF] Zenetos | Annotated list of marine alien species in the Mediterranean with records of the worst invasive species[END_REF]Peristeraki et al., 2006;[START_REF] Streftaris | Alien Marine Species in the Mediterranean -the 100 ‗Worst Invasives' and their Impact[END_REF]. A study done in Lebanon concerned the population structure and the sexual maturity of this fish in the Lebanese and Syrian waters in order to shed light on the severity of this problem [START_REF] Khalaf | Population structure and sexual maturity of the pufferfish Lagocephalus sceleratus (Osteichthyes, Tetraodontidae) in the Lebanese and Syrian marine waters (Eastern Mediterranean)[END_REF] (ANNEX I). In addition, the Mediterranean is also influenced by species introduced from the Atlantic Sea through the Strait of Gibraltar and have reached the Adriatic Sea and even the eastern basin. Some of these Atlantic species are invasive and showed continuous distribution, such as, Parablennius pilicornis [START_REF] Pastor | Occurrence and distribution range of Parablennius pilicornis (Cuvier, 1829) (Actinopterygii: Perciformes: Blenniidae) along the French Mediterranean coast[END_REF], Pomadasys incisus [START_REF] Bodilis | The spread of an Atlantic fish species, Pomadasys incisus (Bowdich, 1825) (Osteichthyes: Haemulidae), within the Mediterranean Sea with new additional records from the French Mediterranean coast[END_REF], and Lampris guttatus (Francour et al., 2010); others showed patchy distributions, such as, Kyphosus sectatrix [START_REF] Francour | First record of Kyphosus sectator (Linnaeus, 1758) (Kyphosidae) along the French Mediterranean coast[END_REF] and Pisodonophis semicinctus [START_REF] Bodilis | Occurrences of the Atlantic species, Pisodonophis semicinctus (Osteichthyes: Ophichthidae), along the Mediterranean coast[END_REF]. Regarding both distributions, the number of individuals of all Atlantic species has increased during the last decade. Their increasing numbers have an impact on native populations and may lead to a reduction in the abundance of endemic species [START_REF] Otero | Monitoring Marine Invasive Species in Mediterranean Marine Protected Areas (MPAs): A strategy and practical guide for managers[END_REF].

The creation of a new Suez canal parallel to the current channel (inaugurated on August 6, 2015)

is expected to double the capacity of the Canal. This expansion is sure to quickly affect the Levantine Basin unfolding a diverse range of effects, at local and regional scales, on both the biological diversity and the ecosystems [START_REF] Galil | ‗Double trouble': the expansion of the Suez Canal and marine bioinvasions in the Mediterranean Sea[END_REF] that will subsequently spread to the rest of the Mediterranean.

Moreover, overexploitation (especially fishing) and bycatch are serious problems for Mediterranean species affecting many threatened marine species, such as, bony and cartilaginous fish, dolphins and marine turtles [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. In addition, the overexploitation of large predators, with change in biomass and composition, could possibly have a greater impact on the stability of an ecosystem, especially the marine one, than removing species farther down the food chain [START_REF] Larkin | Predator-prey relations in fishes: An overview of the theory[END_REF][START_REF] Watson | National Geographic Atlas of the Ocean: The Deep Frontier[END_REF]. Bycatch, as well, can lead to the loss of biological resources along with its biological and ecological impact [START_REF] Hall | Bycatch: problems and solutions[END_REF].

Fisheries

The Mediterranean is one of the oldest and most intensively exploited marine system. Its fisheries target different resources mostly pelagic stocks [START_REF] Abella | Mediterranean stock assessment: current status, problems and perspective: Sub-Committee on Stock Assessment[END_REF]. More than one percent of world landings come from Mediterranean fisheries [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. This fishery is typically characterized by small fishing vessels and multispecies landings. important industrial fisheries mainly target small pelagics (mainly sardines and anchovies) which are principally caught using purse seines and pelagic trawls. Artisanal, as well as industrial fleets, exploit a large number of benthic and demersal species distributed over the generally narrow continental shelves characterizing the Mediterranean Sea. These stocks usually remain within national waters, except in some areas characterized by a wider continental shelf [START_REF] Caddy | Some future perspectives for assessment management of Mediterranean fisheries[END_REF]. Catch assessments are difficult in the Mediterranean because of the multi-specific and multi-gear characteristics of most of its fisheries, the dispersed landing sites and the small fraction of the catch that generally passes through organized fish markets. Sometimes the same stocks are exploited by diverse fleets as their geographical distribution often exceeds the national waters of a single country [START_REF] Abella | Mediterranean stock assessment: current status, problems and perspective: Sub-Committee on Stock Assessment[END_REF]. Furthermore, juveniles and commercially important species or untargeted species constitute the unknown quantity of bycatch, with some species often discarded dead at sea. Invertebrates constitute a minor fishery sector for most countries in the concerned area, partly due to cultural purposes [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF].

The Mediterranean Sea and Black Sea make up together FAO Fishing Area 37 (FAO, 2004). It is divided into four subareas, each of which has its own divisions: Western Mediterranean (Subarea 37.1), Central Mediterranean (Subarea 37.2), Eastern Mediterranean (Subarea 37.3), and Black Sea (Subarea 37.4) (Table 1) (Figure 3). The Food and Agriculture Organization (FAO) has three main goals: the eradication of hunger, food insecurity and malnutrition; the elimination of poverty and the driving forward of economic and social progress for all; and, the sustainable management and utilization of natural resources, including land, water, air, climate and genetic resources for the benefit of present and future generations (FAO, 2015a).

FAO Fisheries and Aquaculture is one department of FAO. It contributes significantly to improving the well-being of poor and disadvantaged communities in developing countries and to achievement of several of the Millennium Development Goals, especially those related to poverty reduction and food and nutrition security, environmental protection and biodiversity. Its main mission is to strengthen global governance and the managerial and technical capacities of members and to lead consensus-building towards improved conservation and utilization of aquatic resources. In this context, the fisheries divisions of this department are employed in this study (FAO, 2015b).

Chondrichthyans: Status, fisheries and threats

Worldwide overview

Chondrichthyans make up one of the oldest and most ecologically diverse vertebrate families:

sharks and their relatives, the batoids (including skates, rays, guitarfishes and sawfishes) and chimaeras are all chondrichthyans, or cartilaginous fishes [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF]. Their classification according to [START_REF] Nelson | Fishes of the World[END_REF] comprises 14 orders and 54 families (ANNEX II). The class constitutes a conservative evolutionary group of around 1200 species which arose more than 400 million years ago and rapidly became top predators in aquatic food webs [START_REF] Compagno | Alternative life-history styles of cartilaginous fishes in time and space[END_REF][START_REF] Kriwet | First direct evidence of a vertebrate threelevel trophic chain in the fossil record[END_REF]. Most chondrichthyans are marine creatures, although many utilize estuaries, particularly as nurseries. Some even enter or are endemic to fresh water. Chondrichthyans can be present in immediate subtidal zone offshore to coastal, bathyal (200-2000m) and even abyssal habitats (>2000m). Most of them are predators, although some species may specialize on small benthic infaunal animals, such as polychaetes or amphipods. Other species, particularly the myliobatids, may consume hard-shelled bivalve molluscs. Most sharks consume fish and crustaceans, although white sharks prefer marine mammals, and basking sharks and whale sharks filter zooplankton from the sea [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF].

Cartilaginous fish are characterized by their conservative life-history traits. They have the latest maturity and the slowest reproduction of all vertebrates; they display long gestation periods and some of the highest levels of maternal investments in the animal kingdom [START_REF] Cortés | Life History Patterns and Correlations in Sharks[END_REF]. These life history traits have been leading to low population growth rates and less compensation in juvenile survival, making them intensively vulnerable to elevated fishing exploitation and mortality (Musick, 1999b;[START_REF] Cortés | Incorporating uncertainty into demographic modeling: Application to shark populations and their conservation[END_REF][START_REF] García | The importance of habitat and life history to extinction risk in sharks, skates, rays and chimaeras[END_REF][START_REF] Dulvy | Life histories, population dynamics, and extinction risks in chondrichthyans[END_REF].

Elasmobranchs are essential to the balance of marine ecosystems. They have a key role, since they clean oceans of injured or sick prey, and thus contribute to maintain healthy populations.

Furthermore, these top-predators regulate certain populations of carnivorous fish. The consequence of an over-exploitation of elasmobranchs would be an increase of forage fish, which would ultimately lead to algal and jellyfish blooms in oceans. Therefore, their decrease can lead to fishing down the food web and can disrupt ecosystem. For humains, it would mean an increase of the importance of organisms with less commercial significance and eating fish, shellfish and seafood would become scarcer.

The center of greatest chondrichthyan biodiversity lies in the Indo-West Pacific Region [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF] (Figure 4). [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF] identified three main hotspots where the biodiversity of sharks and rays was particularly seriously threatened -the Indo-Pacific Biodiversity Triangle, Red Sea, and the Mediterranean Sea -and claim that national and international action is required to protect them from overfishing. Chondrichthyans are often caught incidentally; however, they are mainly regarded as valuable bycatch of fisheries that focus on more productive teleost fish species, such as tunas or groundfishes (Stevens et al., 2005). They are mainly exploited for their meat, fins, livers and gill rakers carry high value; therefore, fishing pressure on chondrichthyans is increasing [START_REF] Fowler | Elasmobranch Biodiversity, Conservation and Management[END_REF][START_REF] Clarke | Global estimates of shark catches using trade records from commercial markets[END_REF][START_REF] Clarke | Social, economic and regulatory drivers of the shark fin trade[END_REF][START_REF] Lack | Trends in global shark catch and recent developments in management[END_REF]. The globalized trade to meet Asian demand for shark fin soup (traditional and expensive Chinese dish) is the main cause for shark fishing. This profitable trade also affects shark-like rays such as wedgefishes and sawfishes. It is mainly unregulated across the 86 countries and territories that exported large amounts of fins to Hong Kong (a major fin trade hub) in 2010 [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF] (Figure 5).

However, bans on ‗finning' (the removal of a shark's fins and discarding the carcass at sea is currently one of the regional and international management measures for sharks and rays through most Regional Fisheries Management Organizations (RFMOs) [START_REF] Fowler | Shark fins in Europe: Implications for reforming the EU finning ban[END_REF].

Figure 5: The main shark and ray fishing nations are gray-shaded according to their percent share of the total average annual chondrichthyan landings reported to FAO from 1999 to 2009. The relative share of shark and ray fin trade exports to Hong Kong in 2010 are represented by fin size [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF].

According to the Food and Agricultural Organization of the United Nations (FAO, 2011), elasmobranch landings have increased progressively to peak in 2003 and then showed a decline since then (Figure 6a); and rays have shown to dominate the landings in the past four decades (Figure 6b). Elasmobranch fisheries worldwide have expanded due to growing demand (particularly for highly valuable parts such as shark fins), the availability of new areas (i.e. open ocean, deep-sea bottom), and the use of highly technically equipped fishing vessels [START_REF] Casey | Near extinction of a large, widely distributed fish[END_REF][START_REF] Clarke | Social, economic and regulatory drivers of the shark fin trade[END_REF][START_REF] Worm | Global catches, exploitation rates, and rebuilding options for sharks[END_REF]. Moreover, most chondrichthyan catches are unregulated and often misidentified, unrecorded, aggregated, or discarded at sea, resulting in a lack of species-specific landings information, and the true catch is estimated 3 or 4 times greater than that reported [START_REF] Barker | Managing global shark fisheries: suggestions for prioritizing management strategies[END_REF][START_REF] Clarke | Global estimates of shark catches using trade records from commercial markets[END_REF][START_REF] Ferretti | Loss of large predatory sharks from the Mediterranean Sea[END_REF][START_REF] Iglésias | Taxonomic confusion and market mislabelling of threatened skates: important consequences for their conservation status[END_REF][START_REF] Bornatowski | Shark mislabeling threatens biodiversity[END_REF][START_REF] Worm | Global catches, exploitation rates, and rebuilding options for sharks[END_REF].

Chondrichthyan life history traits

Life history traits are molded by the energy available in the environment for the distribution among different biological processes and by the interactions that influence distribution decisions.

The energy available for distribution depends ultimately on the primary productivity of the ecosystem (Arendt and Reznick, 2005), while the strength of biological interactions depends on many ecosystem characteristics, including physical structure [START_REF] Gotceitas | Predator foraging success and habitat complexity: quantitative test of the threshold hypothesis[END_REF][START_REF] Almany | Differential effects of habitat complexity, predators and competitors on abundance of juvenile and adult coral reef fishes[END_REF] and diversity [START_REF] Sinclair | Patterns of predation in a diverse predator-prey system[END_REF][START_REF] Duffy | Why biodiversity is important to oceanography: potential roles of genetic, species, and trophic diversity in pelagic ecosystem processes[END_REF]. Studies on life history parameters such as age and growth, along with basic information on distribution, abundance, movements, feeding, reproduction and genetics, are essential for biologists to understand and predict how populations will grow and how they will respond to fishing pressure.

Species, especially chondrichthyans, exhibiting conservative life histories such as late age-atmaturity, large size, slow growth and low rate of potential population increase appeared more vulnerable to exploitation and decreased more in abundance than others [START_REF] Jennings | Life history correlates of responses to fisheries exploitation[END_REF][START_REF] Jennings | Structural change in an exploited fish community: a consequence of differential fishing effects on species with contrasting life histories[END_REF]. These fishes are less productive and fundamentally more vulnerable to extinction than bony fishes [START_REF] Myers | Extinction, survival or recovery of large predatory fishes[END_REF]. Their reproductive strategies along with the relatively close relationship between parent stock and subsequent recruitment from their live-borne or egg-borne early development, opposes those employed by all but a few examples of the teleosts, which support most fisheries. The vulnerability of species of this fish class has been linked to the combination of large maximum body size, slow growth, late maturation (at a large size), and long lifespan [START_REF] Walker | Sensitive skates or resilient rays? Spatial and temporal shifts in ray species composition in the central and north-western North Sea between 1930 and the present day[END_REF][START_REF] Dulvy | Fishery stability, local extinctions, and shifts in community structure in skates[END_REF][START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF][START_REF] Frisk | Estimation and analysis of biological parameters in elasmobranch fishes: a comparative life history study[END_REF]. Life histories are constrained by compromises; slow-growing species tend to be large bodied, mature later in life and have lower annual reproductive output [START_REF] Charnov | Life History Invariants: Some Explorations of Symmetry in Evolutionary Ecology[END_REF][START_REF] Reynolds | Patterns of change in the size spectra of numbers and diversity of the North Sea assemblage, as reflected in surveys and models[END_REF][START_REF] Frisk | The population dynamics of little skate Leucoraja erinacea, winter skate Leucoraja ocellata, and barndoor skate Dipturus laevis: predicting exploitation limits using matrix analyses[END_REF][START_REF] Roff | Life History Evolution[END_REF], as the case of chondrichthyans.

Accordingly, studies on life history traits are indispensable for the protection, conservation and fishery management of these top predators that have an important role in the ecosystem.

Mediterranean chondrichthyans

The Mediterranean Sea is identified as one of the three main hotspots where the diversity of sharks and rays is particularly seriously threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. It holds 80 chondrichthyan species comprising 45 shark species from 17 families and 34 batoid species from 9 families and one chimaera species (almost 7% of total living chondrichthyans in the world) [START_REF] Compagno | Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes[END_REF][START_REF] Compagno | A Field Guide to the Sharks of the World[END_REF][START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF][START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF]. Out of these, 71 were assessed by the International Union for the Conservation of Nature (IUCN), where 42.25 percent are Vulnerable and Endangered to Critically Endangered, 18.31 percent are Near Threatened and 25.35 percent are Data Deficient [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF] (Table 2).

Table 2: The number of chondrichthyan species in each IUCN Red List category [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF].

IUCN Red List categories Number of species

Critically endangered (CE) 13

Endangered (E) 08

Vulnerable (VU) 09

Near Threatened (NT) 13

Least Concern (LC) 10

Data Deficient (DD) 18

Not Evaluated (NE) 0

Total number of species [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF] took into account new published data on the systematic of elasmobranchs and critically analyzed literature data to consider the presence of a total of 86 species of elasmobranchs in the Mediterranean Sea. According to these authors, these species consisted of 49 shark species from 17 families and 37 batoids species from 9 families.

Only 4 batoid species (Leucoraja melitensis, Raja polystigma, Raja radula and Mobula mobular) could be considered endemic [START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF] with Leucoraja melitensis considered endemic threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF].

The highest concentration of elasmobranchs are observed in the coastal waters of the western Mediterranean, especially along the northwestern coast (Figure 7) [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF], probably owing it to the highly oligotrophic nature of the eastern basin [START_REF] Azov | Eastern Mediterraneana Marine Desert?[END_REF]. This confirms the lack of homogeneity in the distribution of elasmobranchs in this area [START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF].

Figure 7: Spatial patterns of elasmobranchs richness in the Mediterranean Sea [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF].

Furthermore, various species exhibit different distribution patterns. For instance, the small tooth sand tiger shark Odontapsis ferox seems to inhabit a particular area of Lebanon [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF]. The rather rare Basking Shark Cetorhinus maximus is constantly present in the eastern Adriatic, where its occurrence highly increased between 2000 and 2002. In addition, aggregations of this latter shark have been observed in the northern Balearic, the northern Adriatic, and the Tyrrhenian Sea [START_REF] Walker | Regional Overviews: Northeast Atlantic (including Mediterranean and Black Sea). In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF][START_REF] Soldo | Basking shark (Cetorhinus maximus) occurrence in relation to zooplankton abundance in the eastern Adriatic Sea[END_REF]. Finally, the Great White Shark, Carcharodon carcharias, the Sandbar shark Carcharhinus plumbeus, and probably many other species have nursery areas in Tunisian waters [START_REF] Saidi | Les requins du golfe de Gabès: Diversité et écobiologie de trois espèces à importance économique Carcharhinus plumbeus, Mustelus mustelus & M. punctulatus[END_REF][START_REF] Enajjar | Diversité des Rajiformes et étude eco-biologique de Rhinobatos rhinobatos et Glaucostegus cemiculus (Famille des Rhinobatidae) du Golfe de Gabès (Tunisie)[END_REF].

Mediterranean chondrichthyan fisheries and threats

The state of cartilaginous fish (chondrichthyans) in the Mediterranean Sea is much more devastating than it is worldwide: 42% of the shark species are threatened in the region in comparison with 17% globally, hence, describing the Mediterranean as the most dangerous sea in the world for cartilaginous fishes [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF].

Elasmobranchs fish catches represent only 1.1 percent of the total landings in the Mediterranean Sea [START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF]. According to the Food and Agricultural Organization (FAO), chondrichthyan fish landings in the Mediterranean increased from 10000 to 25000 tons between 1970 and 1985; however, declines were then reported to 1000 tons by 2004 [START_REF] Sgrst | Report of the Subgroup on Resource Status (SGRST) of the Scientific[END_REF]FAO, 2006). Moreover, large and smaller commercially significant species have marked a decline in different areas of the Mediterranean [START_REF] Ferretti | Loss of large predatory sharks from the Mediterranean Sea[END_REF][START_REF] Dell'apa | Trends of fish and elasmobranch landings in Italy: associated management implications[END_REF][START_REF] Ferretti | Long-term change in a meso-predator community in response to prolonged and heterogeneous human impact[END_REF][START_REF] Ligas | Long-term trajectory of some elasmobranch species off the Tuscany coasts (NW Mediterranean) from 50 years of catch data[END_REF]. The major chondrichthyan fishing countries within the Mediterranean are Turkey, Tunisia, Greece, Italy and Spain and the species most commonly taken in coastal fisheries are: smoothounds Mustelus spp., skates Rajids, catsharks Scyliorhinus spp., dogfish Squalus spp., eagle rays Myliobatids and whiptail stingrays Dasyatids [START_REF] Walker | Reproduction in fisheries science[END_REF].

Bycatch and intensive fishing activities are severe threats for cartilaginous fish species [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF] (Figure 8). Bycatch that is returned to sea is not reported and the number of sharks caught as bycatch cannot be exactly estimated [START_REF] Camhi | Sharks and their relatives -Ecology and Conservation[END_REF][START_REF] Walker | Regional Overviews: Northeast Atlantic (including Mediterranean and Black Sea). In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF]. Although the Mediterranean lacks pelagic fisheries targeting migratory oceanic sharks, longline fisheries targeting valuable teleost (swordfish and tunas) strictly threaten chondrichthyans taken as bycatch in this fishery (ICCAT, 2001). Mortality in mixed species fisheries and bycatch fisheries also pose very significant threats to chondrichthyans [START_REF] Musick | Management techniques for elasmobranch fisheries[END_REF]Stevens et al., 2005). Furthermore, benthic trawls and increased fishing intensities due to the advancement of fishing gear have resulted in a decline for many chondrichthyan species especially in the northwestern Mediterranean [START_REF] Walker | Regional Overviews: Northeast Atlantic (including Mediterranean and Black Sea). In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF]. For instance, large coastal shark species are more seriously affected by bycatch because they are more exposed to intensive fishing [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF]. In addition, chondrichthyans are also targeted by recreational sport fisheries that have increased especially off the Italian, Spanish and French coasts targeting species such as the Thresher Sharks Alopias spp. and the Blue Shark Prionace glauca [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF].

The increase in human population also has adverse effects on the chondrichthyans of the Mediterranean. Critical coastal habitats of elasmobranchs have been degraded due to booming urban and industrial development [START_REF] Camhi | Sharks and their relatives -Ecology and Conservation[END_REF]Stevens et al., 2005). Furthermore, pollution also negatively affects chondrichthyans in the Mediterranean by contaminating food resources (UNEP-MAP and RAC/SPA, 2003). Trace metals have been found in the organs of several elasmobranchs, such as the Gulper Shark Centrophorus granulosus [START_REF] Hornung | Trace metal content in deep-water sharks from the eastern Mediterranean Sea[END_REF].

In addition, a total of eight alien chondrichthyans were recorded in the Mediterranean from Atlantic or Indo-Pacific origins (Table 3). Himantura uarnak and Torpedo (Torpedo)

Sinuspersici were observed in the Eastern Mediterranean [START_REF] Ali | Sharks and rays in Syrian sea waters (in Arabic with abstract in English)[END_REF][START_REF] Saad | Liste commentée des Chondrichthyens de Syrie (Méditerranée orientale)[END_REF][START_REF] Ali | First records of the Honeycomb Stingray, Himantura uarnak (Forskål, 1775), off the Syrian coast (eastern Mediterranean) (Chondrichthyes: Dasyatidae)[END_REF]. There are almost no records regarding the potential competition of these species with local ones (for habitat or food). Until now and up to the general knowledge, these species haven't constituted any threats for cartilaginous fish populations in the area.

Table 3: The alien chondrichthyans of the Mediterranean Sea.

Chondrichthyan alien species Probable origin Reference

Bignose Shark Carcharhinus altimus (Springer, 1950) Tropical Atlantic [START_REF] Golani | The marine ichthyofauna of the eastern levant-history, inventory, and characterization[END_REF] Moreno and Hoyos (1983) [START_REF] Hemida | Notes on the Carcharinids of the Algerian basin[END_REF] Indo-Pacific [START_REF] Ben-Tuvia | Two Indo-Pacific Fishes, Dasyatis uarnak and Upeneus moluccensis, in the Eastern Mediterranean[END_REF] Ben-Tuvia (1966) [START_REF] Mouneimne | Liste des poissons de la côte du Liban (Méditerranée orientale)[END_REF] El Sayed (1994), [START_REF] Basusta | Two new records for the Turkish seas: Round stingray Taeniura grabata and skate stingray Himantura uarnak (Dasyatidae)[END_REF] Halavi Guitarfish Glaucostegus halavi (Forsskäl, 1775) - [START_REF] Souissi | First confirmed record of the Halave's guitarfish, Rhinobatos halavi (Forsskål, 1775) (Chondrichthyes: Rhinobatidae) in the Mediterranean Sea with the description of a case of albinism in elasmobranchs[END_REF] Marbled Electric Ray Torpedo (Torpedo) sinuspersici (Olfers, 1831) Indo-Pacific [START_REF] Saad | Liste commentée des Chondrichthyens de Syrie (Méditerranée orientale)[END_REF] Finally, climate change can have a potential effect on fish, especially chondrichthyans. The increase in temperature of marine domains and changes in other environmental variables can lead to declines in fish populations and biomasses due to climate changes. Increased temperatures are expected to change the phenology of fish life cycles and change the forage resources of fishes differentially thus likely leading to very difficult-to-predict community changes relating to mis-matches of co-evolved predator-prey relationships [START_REF] Hobday | Impacts of climate change on Australian marine life: Part C. Literature Review[END_REF].

Silky

Climate change induces effects at the global level, with effects in the Mediterranean too [START_REF] Lejeusne | Climate change effects on a miniature ocean: the highly diverse, highly impacted Mediterranean Sea[END_REF]. Mediterranean ecosystems may be among the most impacted by global change drivers [START_REF] Sala | Global Biodiversity Scenarios for the Year 2100[END_REF]. [START_REF] Lyne | Economic analysis of identified impacts of climate change: Marine impacts[END_REF] conservatively projected that the expected increases in Australian ocean temperatures would cause a 35% overall economic decline of Australian fisheries by 2070, and that temperate Australian fisheries will be more vulnerable than tropical ones. Moreover, regarding cartilaginous fish species, [START_REF] Chin | An integrated risk assessment for climate change: analysing the vulnerability of sharks and rays on Australia's Great Barrier Reef[END_REF] showed that for the Great Barrier Reef in Australia, freshwater/estuarine and reef associated sharks and rays are most vulnerable to climate change, and that vulnerability is driven by case-specific interactions of multiple factors and species attributes. Changes in temperature, freshwater input and ocean circulation will have the most widespread effects on these species.

Various management tools for coastal ecosystems

Currently, at national and international levels, political, scientific and managing parties have an important set of tools for ecosystem management coastlines.

A number of measures targets particularly professional fishing and concerns limitation measures.

For instance, governments have quotas to reduce fishing effort. These measures consist to establish quotas on total catches, to reduce the number and power of vessels, fishing time, number of fishing gear on board, etc.

The decrease in fishing effort can also result from introducing mesh regulations, and fishing periods depending on the species. Such measures are generally not well received by professional fishermen because of their restrictive character. Moreover, these measures are considered little effective currently, mainly because policies find it difficult to enforce on the field these management measures [START_REF] Pauly | Counting the last fish[END_REF]. Another measure that seems more accepted by professional fishermen is setting fishing areas. This tool consist to establish no-fishing zones for all or part of species, over a predefined period (months to years) and area. But today, two other management tools are put forward by politicians and managers for their protective power of marine resources and of restoration of biodiversity: Marine Protected Areas (MPA) and Artificial

Reefs (AR) [START_REF] Claudet | Marine protected areas and artificial reefs: A review of the interactions between management and scientific studies[END_REF]. The positive effects of MPA have been widely shown internationally, and they benefit from over 30 years of experience [START_REF] Mosquera | Conservation benefits of marine reserves for fish populations[END_REF][START_REF] Claudet | Marine protected areas and artificial reefs: A review of the interactions between management and scientific studies[END_REF]. At a longer term, one of the benefits of MPAs for fisheries is the -spillover effect‖ (area around the no-take zone will benefit fishermen due to the overproduction of fish) [START_REF] Goñi | Spillover from six western Mediterranean marine protected areas: evidence from artisanal fisheries[END_REF][START_REF] Forcada | Effects of habitat on spillover from marine protected areas to artisanal fisheries[END_REF].

However, the MPA are often regarded by professionals and recreational fishers as areas where all human activities are prohibited and therefore negatively perceived by those users. Unlike MPA, ARs do not suffer from this negative view. Thus, this management tool is experiencing a real boom in many countries for 20 years [START_REF] Baine | Artificial reefs: A review of their design, application, management and performance[END_REF][START_REF] Tessier | Assessment of French artificial reefs: due to limitations of research, trends may be misleading[END_REF].

Moreover, in the last three decades, several important conventions have highlighted the need for shark conservation and management globally and regionally: Several reports were established reflecting the status and conservation of chondrichthyans. [START_REF] Séret | The Mediterranean chondrichthyan fishes (sharks, rays, skates and chimaeras): status and priorities for conservation[END_REF], [START_REF] Abdulla | Status and conservation of sharks in the Mediterranean Sea[END_REF], UNEP-MAP and RAC/SPA (2007), [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF] gave a reflection on the conservation of cartilaginous fish in the Mediterranean highlighting the threatened status of several sharks and rays including the impacts of overfishing, shark finning, bycatch, pollution and habitat loss on this fish class.


In 2003, the Regional Activity Centre for Specially Protected Areas (RAC/SPA), in the framework of the United Nations Environment Programme (UNEP), created an action plan for the conservation of cartilaginous fishes (Chondrichthyans) in the Mediterranean Sea containing important objectives and implementation measures [START_REF] Spa | Action plan for the conservation of cartilaginous fishes (Chondrichthyans) in the Mediterranean Sea[END_REF]. This action plan aimed to promote the conservation of cartilaginous fish populations, the protection of selected species (endangered), the protection and restoration of critical habitats, the improvement of scientific knowledge, the recovery of depleted stocks, and the induction of public awareness about the conservation of this fish class.

Eastern Mediterranean chondrichthyans

The Eastern Mediterranean as shown previously consists of the Aegean (3.1) and Levant (3.2) subareas of Fishing Area 37 according to FAO. It is characterized by being more oligotrophic and having a lower species diversity than the Western Mediterranean [START_REF] Azov | Eastern Mediterraneana Marine Desert?[END_REF].

The presence of chondrichthyans is described in several areas of the Eastern Mediterranean through several studies performed in the region. In its northeastern region, chondrichthyans were majorly reflected in studies concerning the Aegean Sea and the southern coast of Turkey [START_REF] Kaya | An investigation on the deep sea fishes of the Aegean Sea[END_REF][START_REF] Papaconstantinou | The demersal fish fauna of the North and West Aegean Sea[END_REF][START_REF] Kabasakal | Preliminary data on the feeding ecology of some selachians from the north-eastern Aegean Sea[END_REF][START_REF] Kabasakal | Morphometrics of young kitefin sharks, Dalatias licha (Bonnaterre, 1788), from northeastern Aegean Sea, with notes on its biology[END_REF][START_REF] Filiz | Length-weight relationships of 24 fish species from the North Aegean Sea, Turkey[END_REF][START_REF] Kabasakal | Shark captured by commercial fishing vessels off the coast of Turkey in the northern Aegean Sea[END_REF][START_REF] Kabasakal | First record of a shortfin mako shark, Isurus oxyrinchus Rafinesque, 1810 (Chondrichthyes: Lamnidae) from the Bay of Saroz (NE Aegean Sea)[END_REF][START_REF] Kapiris | New Mediterranean Biodiversity Records[END_REF][START_REF] Yapici | First length-weight relationships of 11 fish species in the Aegean Sea[END_REF][START_REF] Yigin | Age, growth and reproduction of the rough ray, Raja radula (Delaroche, 1809) in Saros Bay (North Aegean Sea)[END_REF]. A few were carried out in Syria [START_REF] Ali | Sharks and rays in Syrian sea waters (in Arabic with abstract in English)[END_REF][START_REF] Ali | First records of the Honeycomb Stingray, Himantura uarnak (Forskål, 1775), off the Syrian coast (eastern Mediterranean) (Chondrichthyes: Dasyatidae)[END_REF][START_REF] Ali | Occurence of Basking Shark, Cetorhinus maximus (Elasmobranchii: Lamniformes: Cetorhinidae), off the Syrian coast (Eastern Mediterranean) with first description of egg case[END_REF]2013). On the other hand, chondrichthyans in the southeastern part of the Eastern Mediterranean were reflected through studies carried from the northern coast of Egypt to the coast of Israel [START_REF] Ben-Tuvia | Two Indo-Pacific Fishes, Dasyatis uarnak and Upeneus moluccensis, in the Eastern Mediterranean[END_REF][START_REF] Ben-Tuvia | Red Sea fishes recently found in the Mediterranean[END_REF][START_REF] Abdelaziz | Food and feeding habits of Raja species (Batoidei) in the Mediterranean waters of Alexandria[END_REF][START_REF] Golani | On deep-water sharks caught off the Mediterranean coast of Israel[END_REF][START_REF] Abdelaziz | Sexuality, reproduction and fecundity of Raja miraletus (L) from the Mediterranean waters off Alexandria[END_REF][START_REF] Ezzat | The food of Raja miraletus Linnaeus 1758 in Mediterranean waters off Alexandria[END_REF].

Nonetheless, almost no studies dealing with cartilaginous fish species were performed along the Lebanese coast, the study area, providing no scientific evidence describing these populations or managing their exploitation in that area. Chondrichthyans were only mentioned in several fish inventories [START_REF] Boulos | Contribution à l'océanographie des pêches au Liban[END_REF][START_REF] Mouneimne | Liste des poissons de la côte du Liban (Méditerranée orientale)[END_REF][START_REF] Mouneimne | Poissons des côtes du Liban (Méditerranée Orientale)[END_REF]1979;[START_REF] Azov | Eastern Mediterraneana Marine Desert?[END_REF][START_REF] Mouneimne | Poissons marins du Liban et de la Méditerranée Oriental[END_REF] and underwater visual census surveys [START_REF] Harmelin-Vivien | The littoral fish community of the Lebanese rocky coast (eastern Mediterranean Sea) with emphasis on Red Sea immigrants[END_REF] carried along the Lebanese coast.

The Lebanese fishery being artisanal and traditional [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF] Several manners were issued by the Ministry of Agriculture aiming to protect these species.

According to the -General Fisheries Commission for the Mediterranean‖ recommendation

Objectives of the study

The beginning of research work on cartilaginous fish species along the Lebanese coast was a necessity. Indeed, this fish class has been progressively exploited along the coast of Lebanon and the ministry decrees are not being executed in an effective manner. Also, there is almost no written knowledge reflecting the presence and the distribution of species of this fish class along the Lebanese coast. Their presence is often documented and presented in various regions of the Mediterranean and its eastern basin; nonetheless, gaps exist all along the Lebanese coast.

Therefore, the lack of data, exploitation and lack of management of this fish class is the basic stimulator for this study.

This thesis aims to contribute to a better knowledge of cartilaginous fishes in the Lebanese marine environment. Emphasis was placed on the following axes:

1-The establishment of an inventory of chondrichthyans along the Lebanese coast and a bibliographic revue dedicated to cartilaginous fish species in the Eastern Mediterranean.

2-

The description of spatio-temporal biodiversity and distribution of chondrichthyans along the Lebanese coast.

3-A focus on the biology and ecology of two threatened and commercially significant elasmobranch species (one shark and one batoid species).

Some chapters of the thesis are presented under the form of articles. Following the present general introduction, constituting Chapter I, the thesis is divided as follows:

Chapter II is dedicated to the presentation of the general -Material and Methods‖ section containing a description of the studied area and the experimental methodologies and statistical tests and analyses employed through the course of this study.

A bibliographic review describing all the studies on cartilaginous fish species in the Eastern Mediterranean is presented in Chapter III. It summarizes all published information on inventories, occurrence, distribution, status, conservation, age and growth, length-weight relationships, reproductive aspects, nutrition and feeding habits and other life history aspects of the cartilaginous fish species in the Eastern Mediterranean.

Chapter IV is dedicated to the representation of the spatio-temporal biodiversity and distribution of cartilaginous fish species in the study area using two complementary data collection methods: Then, a study of the biology and ecology of an Endangered batoid, the Common Guitarfish, Rhinobatos rhinobatos, which is a commercially significant species in Lebanese fisheries is presented in Chapter V. This chapter aims to a better understanding of the population dynamics parameters models of this exploited fish stock in order to ensure the long-term sustainability of this fishery.

Chapter VI presents the biology and ecology of the Gulper Shark, Centrophorus granulosus, classified as Vulnerable by IUCN, which is also an exploited species either as bycatch or targeted. This chapter also aims to describe the characteristics of life-history traits of this deepwater exploited shark population in order to protect, manage and maintain it.

Finally, the general discussion, conclusion, and perspectives of this work are presented in the last chapter (Chapter VII) and several annexes are included at the end of the thesis to complete certain aspects.

Chapter II

Material and Methods

Chapter II: Material and Methods

1.

Characteristics of the study area 10).

The diurnal range remains close to 7°C throughout the year [START_REF] Abi Saab | Contribution à l'étude des populations microplanctoniques des eaux côtières libanaises (Méditerranée orientale)[END_REF]. This study was carried out along the coast of Lebanon, which is situated between the north latitudes of 33°05'45.6''and 34°38'45.6'' and east longitudes 35°06'10.8''and 35°58'37.2''.

The Lebanese coast

The coast of Lebanon is narrow, 3 to 7 km wide. It extends for 220 km from Aarida in the north to Ras Al Naqoura in the south covering 16% (180000 hectares) of Lebanese territory. Land rises sharply from the coast in the north, while forming a narrow coastal plain in the south. The continental shelf is narrow, especially in the south, and the bottoms are majorly rough with wide rocky patches that serve well for standing demersal gear [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF].

Tyre Coast Nature Reserve (TCNR)

The TCNR amounts to an area of 3.8 km² divided into three zones; tourism zone, agricultural and archeological zone, and conservation zone. It is an important nesting site for globally endangered Mediterranean Loggerhead and Green sea turtles, a site containing a wide diversity of ecosystems; marine, agriculture, wetland, that have Mediterranean characteristics. The TCNR is also located on major migratory routes where internationally important bird species have been identified. It has also been a Ramsar site (No. 980) since 16/04/1999. Similarly many management plans were prepared by the MoE through the consultation of experts from various organizations aiming for the protection and the conservation of this reserve [START_REF] Peillen | Définition du statut, du rôle, de la fonction et des mécanismes de gestion des Parcs naturels nationaux et régionaux au Liban et rédaction du cadre réglementaire y afférent[END_REF].

Currents and bathymetry

A general surface current from the Atlantic Ocean passes through the Strait of Gibraltar into the Mediterranean. The major part of this current move eastwards parallel to the North African coast but progressively loses force as it approaches eastwards. This current maintains its track southeast passing through the cap of Tunisia, the Libyan and the Egyptian coasts. It then turns and continues along the Palestinian, Lebanese and Syrian coasts. The intensity of this current and the quantity of water reaching the Levantine basin depends on its flow through the Strait of Gibraltar [START_REF] Nakhle | Le mercure, le cadmium et le plomb dans les eaux littorales libanaises: Apports et suivi au moyen de bioindicateurs quantitatives (Eponges, bivalves, et gasterpodes)[END_REF]. Therefore, the general circulation along the coast of Lebanon is dominant northwards during most of the year along with the general counterclockwise current gyre of the Eastern Mediterranean. This current is locally modified by the configuration of the coastline and the topography of the narrow continental shelf. This results in a series of clockwise directed eddies and small gyres associated with bays and headlands as well as with numerous submarine canyons incised in the continental shelf [START_REF] Goedicke | Submarine canyons on the central continental shelf of Lebanon. The Mediterranean Sea a natural sedimentation laboratory[END_REF]. Water movements along the coast are also strongly related to surface currents and seasonal meteorological factors.

The bathymetry of the coast is barely investigated. However, ultrasound probe bathymetry results from [START_REF] Pfannenstiel | Erlauterungen zu den bathymetrischen karten des ostlichen mittelmeeres[END_REF] and [START_REF] Emery | Bathymetry of the eastern Mediterranean Sea[END_REF] During the survey, bathymetric mapping was carried out using a Simrad EM-300 multibeam echo sounder providing high-resolution bathymetric and backscatter data, at a vessel speed of 7.5

to 10 knots over an area of 11,000 km 2 at depths greater than 200 m [START_REF] Carton | Seismic evidence for Neogene and active shortening offshore of Lebanon (Shalimar cruise)[END_REF] (Figure 11). [START_REF] Carton | Seismic evidence for Neogene and active shortening offshore of Lebanon (Shalimar cruise)[END_REF].

The fishery sector

The Lebanese fishery is artisanal and traditional [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF]. The Lebanese fishing fleet is composed of small scale artisanal vessels less than 12 m in length and typical of many Mediterranean countries [START_REF] Brême | Analyse situationnelle de la Pêche côtière[END_REF][START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Carpentieri | Socio-economic development of the community of the fishermen of Tyre‖ Preliminary analysis of the fishing sector of Tyre (south Lebanon)[END_REF][START_REF] Majdalani | Census of Lebanese Fishing Vessels and Fishing Facilities[END_REF][START_REF] Lelli | Commercial landing and fishing metiers within the artisanal fishery of Tyre, Lebanon. Socio-economic development of the fishing Community of Tyre, Lebanon' promoted by the Italian NGO ‗Ricerca e Cooperazione' in collaboration with Caritas Lebanon and co[END_REF][START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF]PescaMed, 2011;[START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF].

According to the Ministry of Agriculture, a total number of 42 ports are distributed along the Lebanese coast. The majority of these ports do not comply with the technical conditions for the improved development of the fishing sector whether with respect to equipment or management [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF]. The largest fishing ports are distributed according to the governorates as follows: Abdeh, Tripoli and Batroun ports in the North, Dora Port in Mount Lebanon, Ozaaii

Port in Beirut, and Sidon and Tyre Ports in the South (Figure 12). The most common gear used includes trammel nets, longlines, purse seine nets, and lampara nets [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF]. Trawling is legally forbidden although fishing nets with illegal mesh sizes are widely available in the black market [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF]. Most of the gillnets and trammel nets have small mesh sizes and represent more than 50% of the fishing gears used in most part of Lebanese fishing [START_REF] Pinello | Fishing fleet data for 2011[END_REF]. Only few vessels have a Global Positioning System (GPS), while the rest have very limited navigational or safety equipment, and only 20% of the vessels have small electronic fish finders [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF].

According to [START_REF] Pinello | Fishing fleet data for 2011[END_REF], the marine capture fisheries production in Lebanon in the last 10 years was around 3,500 tons per year. The data was derived from the FAO Fisheries and Aquaculture Department. From 2006 onwards the production has remained constant at 3,541 tons due to the fact that Lebanon has stopped sending data to FAO. Therefore, this data does not reflect the status of the Lebanese fisheries production.

Data collection

Data collection was carried out from December 2012 to October 2014 in three different manners in order to target a maximum number of cartilaginous species along the Lebanese coast. Gillnets with mesh sizes of 26, 30 and 40 mm (of length 1 km connected together) were lowered at depths less than 100 m; trammel nets with mesh sizes of 22, 24, 26, 28 and 30 mm (of length 1 km connected together) were lowered at depths greater than 100 m. Longlines of size 5 hooks were lowered at specified depths mainly in the south because it was an additional lowering in the survey. Unfortunately, this gear was not lowered in all the region.

CIHEAM PESCA-Libano

Cartilaginous fish data were collected from the CIHEAM PESCA-Libano project along with the type of gear, the coordinates and the depth of each catch.

Six artisanal fishermen from six different ports in Lebanon were hired to lower the gear at the hauls with the specified coordinates. The technical features of the vessels are represented in Table 4. The crew usually included two to four people (with a minimum of one scientific) and a maximum of two hauls were carried out per day depending on the weather conditions and the technical conditions of the vessel. The right point was reached by means of a global positioning system (GPS) instruments and a sonar was used to confirm the depth. The depth of each haul, observed coordinates, and the meshes of the nets used were recorded. Nets were not loaded in baits; however, the hooks of the longlines were always loaded with baits from chopped fish, such as, herrings (Etrumeus teres), mackerels (Scomber scomber) or tunas (Euthynnus alletteratus).

Fishermen

Data collection had also been performed by randomly hiring fishermen throughout the Lebanese coast with the collaboration of the Lebanese National Council for Scientific Research (CNRSL) -National Center for Marine Sciences -to lower longlines at depths ranging from 30 to 600 m aiming to catch cartilaginous species. Most of the Lebanese artisanal fishermen do not have GPS instruments, so the exact position of the data collected by this manner was not recorded; however, the depth was noted as observed by the professional fishermen.

Fisheries

Data collection has also been performed through observation of major fisheries along the Lebanese coast. The main fishery visited was a principal one in Tripoli, where there are constant cartilaginous catches. Fisheries were visited a minimum number of 5 times per month, and data was collected when specimens were available.

Morphometric measurements

The species were identified according to the Field Identification Guide to the Living Marine Resources of the Eastern and Southern Mediterranean [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF] and Fishes of the Eastern Mediterranean [START_REF] Golani | Fishes of the eastern Mediterranean: Turkish Marine Research Foundation[END_REF].

Prior to dissection, the cartilaginous fish samples were examined for external damages and sexed macroscopically by the observation of the male claspers (Figure 14). The presence of claspers in cartilaginous fish indicated a male gender. The external length of the claspers (L C ) in male specimens was measured from the tip of the clasper to the base of the pelvic fin using a caliper to the nearest millimeter (mm). The sex ratio (males to females) was calculated for each species of cartilaginous fish observed. A list of all the abbreviations of all parameters and their units of measurement in the Materials and Methods section are presented in ANNEX IV. The total length (L T ) was considered to be the length from the tip of the snout to the posterior tip of the caudal fin along the anterior-posterior axis. It was measured to the nearest centimeter below the actual length of the fish using a measuring tape. The fork length (L F ) was measured from the tip of the snout to the fork of the tail, and the standard length (L S ) was measured from the tip of the snout to the origin of the caudal fin also to the nearest centimeter. The total weight (W T ) (less than five kilograms) was measured to the nearest gram (g) using an electric balance. A total weight greater than five kilograms was measured using a scale to the nearest 100 g.

Biological indices and sexual maturity

Dissection was performed and additional measurements were taken. The liver, digestive tube and gonads were removed along with the expanded uteri in the case of a gravid female (Figure 15).

The weight of the liver (W L ) and the weight of the gonads (W G ) including the weight of the testis in males and oviductal glands, accessory glands, ovary and oviducts in females [START_REF] Gristina | Biological information on Target Species: Sex-determination, Maturation stages and Gravimetric indexes[END_REF] were measured to the nearest gram (g) using an electronic balance. These measurements were used to calculate important biological indices, such as, the hepato-somatic index (I H ), the gonado-somatic index (I G ) and the condition factor (K). After the removal of the digestive and reproductive systems, the eviscerated weight of the fish (W E ) was also recorded.

Figure 15: A photograph of a dissected Rhinobatos rhinobatos prior to (a) and after (b) liver removal.

Hepato-somatic index

The knowledge of the hepato-somatic index in fish is very indispensable for the study of its biological functions because the liver is an important energy storage in fish [START_REF] Halton | Practical Exercises in Parasitology[END_REF].

The hepato-somatic index (I H ) as defined by [START_REF] Bulow | Comparisons of two bluegill Populations by Means of the RNA-DNA ratio and Liver-Somatic Index[END_REF] and [START_REF] Adams | Estimation of largemouth bass, Micropterus salmoides Lacépède, growth using the liver somatic index and physiological variables[END_REF] was calculated as:

Since this biological index provides information about the energy reserves, its variation can imply a change in metabolism during the fish's life. This alteration of metabolism can accompany several phases in the life of an elasmobranch, such as, maturation and pregnancy [START_REF] Yano | Reproductive Biology of the Black Dogfish, Centroscyllium fabricii, collected from waters off Western Greenland[END_REF][START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF].

Gonado-somatic index

The change in the ovaries and testes weights of elasmobranchs during the study period was investigated using the gonado-somatic index (I G ). This index determines the variations in gonad weight throughout the process of maturation in relation to the weight of the fish. It was defined by [START_REF] Bougis | Recherche biométriques sur les rougets (M. barbatus L., M. surmuletus L.)[END_REF] as:

Condition factor

The condition factor (K) of a fish reflects its ‗condition', ‗fatness', and ‗well-being' [START_REF] Tesch | Age and growth[END_REF]. It can indicate periods of physiological stress or phenomena, such as, spawning, mating, population density alterations, feeding conditions, and temperature variations [START_REF] Lecren | The Length-Weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis)[END_REF][START_REF] Braga | Estudo entre fator de condição e relação peso/comprimento para alguns peixes marinhos[END_REF][START_REF] Loefer | Life history of the Atlantic sharpnose shark (Rhizoprionodon terraenovae)(Richardson, 1836) off the southeastern United States[END_REF]. It was defined by [START_REF] Fulton | The rate of growth of fishes[END_REF] as:

Sexual maturity

After identification, the type of reproduction (oviparous or ovoviviparous) of the fishery and fishermen data and target species was determined using the information provided in [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF]. All elasmobranchs whose biology was taken into account in this study were ovoviviparous. During dissection, the sexual maturity of each elasmobranch caught was also determined by the observation of the female and male gonads using the gonad aspects for ovoviviparous elasmobranchs as defined in the ‗Instruction Manual' of the MEDITS -International bottom trawl survey in the Mediterranean -Version 6 (MEDITS, 2012).

The different reproductive system aspects, sexual maturation states and maturity stages for the ovoviviparous elasmobranchs are represented in Table 5.

Stomach contents analysis

The stomach content analysis was only undertaken into account in this study for the species Rhinobatos rhinobatos. During dissection of this target species, the stomachs were removed and their total weights (W S ) were measured. Stomachs containing food were preserved in 4% formaldehyde until identification; empty stomachs were also noted. Upon treatment, full stomachs were rinsed using running water and the contents were separated using a sieve. Each prey was identified to the lowest possible taxon and counted. The total weight of each prey group was measured if possible to the nearest gram (Figure 16).

Figure 16: The separation, identification and weighing of the prey items found in the stomach of a Rhinobatos rhinobatos specimen.

Several indices were then calculated to analyse the diet of the target species studied, reflecting its diet composition and feeding strategy.

Diet composition

According to [START_REF] Hyslop | Stomach contents analysis--a review of methods and their application[END_REF], the coefficient of vacuity (C V ) that reflects the richness or lack of food in the environment was calculated:

where E V is the number of empty stomachs and N is the total number of stomachs examined.

The percentage of fullness (F I ) was also calculated for each stomach:

where W P is the weight of the prey items in each stomach.

Stomach fullness was classified based on a five-point scale estimated by the percentage of fullness: empty, partially empty (1-25%), slightly full (26-50%), partially full (51-75%), and full (76-100%).

Moreover, three indices were calculated to indicate the importance of the different prey items in the diet of the target species according to [START_REF] Hynes | The food of freshwater sticklebacks (Gasterosteus aculeatus and Pygosteus pungitius) with a review of methods used in studies of the food of fishes[END_REF], [START_REF] Hyslop | Stomach contents analysis--a review of methods and their application[END_REF] and [START_REF] Bowen | Quantitative description of the diet[END_REF]:

1. The frequency of occurrence (O % )

where N P is the number of stomachs containing a specific prey group and M is the number of stomachs with prey remains.

The coefficient of prey numerical abundance (N % )

where n is the number of prey of each taxonomic group and n P is the total number of prey items 3. The percentage of weight (W % )

where m is the mass of prey of each taxonomic group and m P is the total mass of prey items.

Using these three indices, a fourth index was estimated to better reflect the importance of each prey item in the stomachs of the target species. This index was defined by [START_REF] Pinkas | Food habits of albacore, bluefin tuna, and bonito in Californian waters[END_REF] as the Index of Relative Importance (I RI ) and modified by [START_REF] Hacunda | Trophic relationships among demersal fishes in a coastal area of the Gulf of Maine[END_REF] to be calculated as:

( )

Finally, the percent of I RI (I %RI ) for each prey type (i) was estimated in order to make comparisons easier among food types [START_REF] Cortés | A critical review of methods of studying fish feeding based on analysis of stomach contents: application to elasmobranch fishes[END_REF] as:

%RI RI ∑ RI
where n is the total number of prey types.

Feeding strategy

The feeding strategy of the target species was analysed according to the graphical method proposed by [START_REF] Costello | Predator feeding strategy and prey importance: a new graphical analysis[END_REF]. This graph displays the relationship between the frequency of occurrence (O % ) (abscissa) and the coefficient of prey numerical abundance (N % ) (ordinate). It particularly illustrates the dominance and the rarity of each group of prey in both seasons and the specialized or generalized feeding strategy (Figure 8).

Figure 17: The graph of [START_REF] Costello | Predator feeding strategy and prey importance: a new graphical analysis[END_REF] and its interpretation concerning feeding strategy and prey importance (with O % as the frequency of occurrence and N % as the coefficient of prey numerical abundance).

The most dominant prey items in the diet of the target species are situated to the upper right of the graph (high N % and O % ), whereas the rare prey items are situated to the bottom left (low N % and O % ).

Other data collected

Other data was collected from the cartilaginous fish samples of target species and of the fishery and fishermen data. The fork length L F and standard length L S were measured the tip of the snout to the fork of the tail, and from the tip of the snout to the origin of the caudal fin, respectively.

Moreover, spines were collected from the target species Centrophorus granulosus for probable age estimation. This data is not used in this study but will probably be included in further studies.

Catch per unit effort

The catch per unit effort (CPUE) was only calculated for the cartilaginous species caught during the CIHEAM-PESCA Libano survey, during which long liners, trammel nets and gillnets were lowered at specific hauls with predetermined coordinates and depths. The CPUE for the cartilaginous fish caught during the survey was calculated using the statistical software ‗R project' (R Development Core Team, 2014) in kilogram and in number according to the following:

1. CPUE in kilograms according to each meshed gear (Index G: gear; Index M: mesh) for trammel nets, gillnets, and longlines:

∑ T ⁄
where i is the cartilaginous species caught in a specific meshed gear or longline in the predetermined haul, N Ci,G,M the total number of cartilaginous species i caught in the same meshed gear or longline also in the predetermined haul, and E the effort which is considered one because each gear was lowered once with the same effort duration.

2. CPUE in number according to each meshed gear (Index G: gear; Index M: mesh) for trammel nets, gillnets, and longlines:

∑

where N Ci,G,M is the total number of the cartilaginous species i caught in a specific meshed gear or longline in the predetermined haul and E the effort which is considered one because each gear was lowered once with the same effort duration.

Biodiversity indices

Seasonal and spatial biodiversity were assessed by calculating several diversity indices considering S as the total number of species recorded in the sample and N as the total number of individuals in the same sample [START_REF] Magurran | Measuring biological diversity: Blackwell Science[END_REF]. All these indices were calculated using the ‗vegan' package on the statistical software ‗R project' (R Development Core Team, 2014).

The Shannon Index

One of the most used of all diversity measures is the Shannon Index. This index assumes that individuals are randomly sampled from an infinitely large community [START_REF] Pielou | Ecological diversity[END_REF] and that all species are represented in the sample. It accounts for both abundance and evenness of the species present where a higher index value represents higher diversity with a maximum value equivalent to lnS. The Shannon Index was calculated using the diversity function and choosing -Shannon‖ for index as:

∑

where p i is the proportion of individuals found in the ith species and calculated as [START_REF] Pielou | An introduction to mathematical ecology[END_REF]:

where n i is the total number of individuals in the ith species.

The Shannon Index takes into account the degree evenness of species abundances; however, no separate value is given. It is thus possible to calculate the Shannon evenness measure separately as [START_REF] Pielou | An introduction to mathematical ecology[END_REF][START_REF] Pielou | Ecological diversity[END_REF]:

where H max = lnS represents the maximum diversity where all species had equal abundances.

Simpson's Index

The Simpson index is one of the most meaningful and robust diversity measures indicating the variance of a species abundance distribution and emphasizing the species richness component of diversity [START_REF] Magurran | Measuring biological diversity: Blackwell Science[END_REF]. In fact, the probability of any two individuals picked randomly from an infinitely large community belonging to the same species was defined by [START_REF] Simpson | Measurement of diversity[END_REF] as:

∑

where p i is the proportion of individuals found in the ith species.

However, the appropriate form for a finite measure was defined as:

∑ ( [ ] [ ] )
where n i is the total number of individuals in the ith species.

This form gives an index D which is inversely proportional to the diversity. As D increases, the diversity decreases. Therefore, a better expression for Simpson's Index, as recommended by [START_REF] Lande | Statistics and partitioning of species diversity, and similarity among multiple communities[END_REF] is:

where the value of this index ranges between 0 and 1, which represents the maximum diversity.

It was also calculated using the diversity function and choosing the index -Simpson‖.

Simpson's diversity measures emphasizes dominance, as opposed to the richness component of diversity, and does not purely measure evenness [START_REF] Magurran | Measuring biological diversity: Blackwell Science[END_REF].

Taxonomic diversity

Two or more assemblages can have the same number of species and an equivalence in species abundance, but vary in the diversity of the taxa to which the species belong [START_REF] Magurran | Measuring biological diversity: Blackwell Science[END_REF].

Therefore, measures of taxonomic diversity should be used. One development was Clarke and

Warwick's taxonomic distinctness measure [START_REF] Clarke | A taxonomic distinctness index and its statistical properties[END_REF][START_REF] Warwick | Taxonomic distinctness and environmental assessment[END_REF]. This measure describes the taxonomic distance between two randomly chosen organisms using the phylogeny of all species in an assemblage. It is in two forms: ∆ or ‗taxonomic diversity' and ∆ * or ‗taxonomic distinctness'. ∆ considers species abundances as well as taxonomic relatedness and measures the path between two randomly chosen individuals that might belong to the same species. ∆ * purely measures taxonomic relatedness considering each individual coming from different species. When such data is used, these measures are reduced to a single measure, ∆ + , indicating the average taxonomic distance between two randomly selected species and can be calculated as:

[∑ ∑ ] * ( ) ⁄ + ⁄
where s is the number of species in the study and ω ij is the length between species i and j.

The taxonomic distances were first calculated using the function taxa2dist from a table containing all the species classified up to their class (ANNEX V). The taxonomic diversity was then calculated using the function taxondive.

Statistical analyses and regressions

Statistics

Several statistical analyses were performed in this study using the statistical software ‗R project' aiming to aid the analysis of results. Both inferential (tests) and descriptives methods (multivariates analyses such as Principal Component Analysis or Canonical Correspondance Analysis) were employed. The methods performed and application purposes are represented in Table 6. depth ([0-200[, [200,400[, [400,600] Factors and modalities: Gear (G, L, T); region (North, South); depth ([0-300[, [300, 600]

Linear regressions

The analysis of reproductive organs growth can determine the size or age at maturity. The presence of a relationship between the development of secondary sexual characteristics and reproductive organs and maturity urged the use of clasper length measurements to estimate the size at maturity [START_REF] Conrath | Reproductive biology. In Management techniques for elasmobranch fisheries[END_REF]. Therefore, a linear regression model was used to evaluate the relationship between total length and clasper length. A steeper slope corresponds to the range of lengths at which the elasmobranch is becoming mature. A linear model function in the statistical software ‗R project'(R Development Core Team, 2014), lm, was used to fit the linear model and estimate the parameters ‗a' and ‗b' of the equation relating clasper length to total length:

The coefficient of determination (r 2 ) was used to evaluate the quality of the model.

Nonlinear regressions

Gonad weight and total length

The most common reproductive measure to plot against length is the clasper length in male elasmobranchs; nevertheless, the weight of other reproductive structures such as the testis and siphon sac are often used in the same manner [START_REF] Teshima | Studies on the reproduction of Japanese dusky smooth-houndes, Mustelus manazo and M. griseus[END_REF][START_REF] Parsons | Seasonal changes in shark testicular structure and spermatogenesis[END_REF][START_REF] Yano | Reproductive biology of the slender smoothhound,Gollum attenuatus, collected from New Zealand waters[END_REF]. However, a power regression is utilized because according to [START_REF] Froese | Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations[END_REF], nonlinear power regressions should be used to represent any regression of weight on length because any weight will scale to the cubic power of length in fish.

A nonlinear least squares function nls was used to estimate the parameters ‗a' and ‗b' of the nonlinear power equation between gonad weight and total length and was implemented on the statistical software ‗R project'(R Development Core Team, 2014):

The start values of these parameters were derived from the log transformation of the two variables using the linear model function (lm), and the coefficient of determination (r 2 ) was used to evaluate the quality of the model.

Length-weight relationship

Length-weight relationships for fish populations help to a better knowledge of the growth rate, age, and other constituents of population dynamics [START_REF] Kolher | Length-weight relationships for 13 species of sharks from the western North Atlantic[END_REF].

A nonlinear least squares function, nls, on the statistical software ‗R project' (R Development Core Team, 2014) was used to estimate of the parameters ‗a' and ‗b' of the nonlinear power equation between gonad weight and total length following [START_REF] Lecren | The Length-Weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis)[END_REF]:

The start values of these parameters were also derived from the log transformation of the two variables using the linear model function (lm) into:

The coefficient of determination (r 2 ) was also used to evaluate the quality of the model.

The type of growth of the fish studied is determined by parameter ‗b'. This parameter is the exponent of the arithmetic form of the weight-length relationship. If b = 3, growth is isometric and the weight increases at the same rate as the length of the fish, indicating that smaller specimens are in the same condition and form as larger ones. If b > 3, growth is positively allometric and the weight increases at a faster rate than the length of the fish, indicating that larger specimens have grown in height or width more than in length. If b < 3, growth is negatively allometric and the length increases at a faster rate than the weight of the fish, indicating that large specimens became more elongated or small specimens were in better nutritional condition at the time of sampling [START_REF] Froese | Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations[END_REF].

Logistic regressions

Size at maturity is also determined by the length at which 50% of the fish sample is mature (L 50 ).

The proportion of mature elasmobranch specimens in each length group is determined. This data is then fitted in a logistic regression and the length at the point of the curve corresponding to 50% mature (P=0.5) indicates the size at which these fish mature. The logistic equation takes the following form:

( )

where P is the proportion of mature elasmobranch specimens in each determined length class, and ‗a' and ‗b' are parameters estimated by fitting the data to the logistic curve.

The length at which 50% of the individuals of specific elasmobranch species are mature was estimated for both sexes using a logistic curve from a generalized linear model (GLM) with logit link using the function glm in the statistical software ‗R project'(R Development Core Team, 2014).

Maps and interpolation

All maps were created on the Quantum Geographic Information System (qGIS) software (QGIS Development Team, 2012). Interpolations were performed on the same software only for the scientific survey data.

Spatial interpolation is the process of using points with known values to estimate values at other unknown points. Spatial interpolation was performed on the CPUE in kilograms and number and species richness according to haul for the shark, batoid, and combined datasets using the Inverse Distance Weighting (IDW) method and the ‗Linear' color interpolation in the software.

The IDW is where the sample points are weighted during interpolation such that the influence of one point relative to another declines with distance from the unknown point to be created.

Weighting is given to sample points by a weighting coefficient that controls how the weighting influence will drop off as the distance from new point increases. The greater the weighting coefficient, the less effect the points will have if they are far from the unknown point during the interpolation process. As the coefficient increases, the value of the unknown point approaches that of the nearest observational point.

Chapter III

The cartilaginous fishes of the Eastern Mediterranean: A literature review on the biology, ecology and geographic range of these species

Introduction

The Mediterranean basin is known for its high biodiversity and the greatest proportions of species records were within the prokaryotic and eukaryotic microbes (26%), subphylum Crustacea (13.2%) and phyla Mollusca (12.4%), Annelida (6.6%), Plathyhelminthes (5.9%), Cnidaria (4.5%), subphylum Vertebrata (4.1%), Porifera (4.0%), Bryozoa (2.3%), subphylum Tunicata (1.3%), and Echinodermata (0.9%), other invertebrate groups (14%), within the Animalia, and Plantae (5%) [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. Nearly one third of the Mediterranean fauna is endemic [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. Moreover, it is considered as one of the first 25 global biodiversity hotspots (Myers et al., 2000a). The Mediterranean Sea has been inhabited for a long time and ecosystems have changed in many ways. Thus, anthropogenic impacts are stronger in the Mediterranean than in any other sea of the world [START_REF] Blondel | Biology and Wildlife of the Mediterranean Region[END_REF]. The loss and damage of habitats through the development of coastal infrastructure, pollution, invasion of exotic species and overexploitation has increased the risk of species extinction in the Mediterranean [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. Cartilaginous fishes in the Mediterranean are generally declining in abundance, diversity and range more than cartilaginous fish populations elsewhere in the world [START_REF] Walker | Regional Overviews: Northeast Atlantic (including Mediterranean and Black Sea). In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF].These decreases can be due to several factors, including the life history characteristics of these fish along with the semi-enclosed nature of the Mediterranean Sea and intense fishing activity throughout its coastal and pelagic waters, effects of habitat loss, environmental degradation and pollution (Stevens, 2005;[START_REF] Walker | Regional Overviews: Northeast Atlantic (including Mediterranean and Black Sea). In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF]. Besides, over the last 200 years, the cartilaginous fishes of the Mediterranean have diminished and are in risk of extinction due to fishing pressure [START_REF] Ferretti | Loss of large predatory sharks from the Mediterranean Sea[END_REF].

The Mediterranean Sea is characterized by a quite high diversity of cartilaginous fish with 45 sharks, 34 batoids, and one chimaera found in its waters [START_REF] Compagno | Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes[END_REF][START_REF] Compagno | A Field Guide to the Sharks of the World[END_REF][START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF]. [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF] identified three main hotspots where the biodiversity of sharks and rays was particularly seriously threatened -the Indo-Pacific Biodiversity Triangle, Red Sea, and the Mediterranean Sea -and claim that national and international action is required to protect them from overfishing. The center of greatest chondrichthyan biodiversity lies in the Indo-West Pacific Region [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF].

Three endemic species, among which one is endemic threatened are also found in the Mediterranean waters [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF] stated that elasmobranches are considered as a significant bycatch of commercial fisheries that target bony fishes and rare are the fisheries targeting sharks. However, the United Nations Food and Agriculture Organization (FAO) suggested that sharks comprise 60% of the catch of cartilaginous fishes in the world (FAO, 1999). Nonetheless, not all the catch is landed and most of the bycatch is discarded dead without any record of the species or capture volume [START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF].

Among 80 species of cartilaginous fish known in the Mediterranean, 71 were assessed in the frame of the International Union for Conservation of Nature (IUCN) red list. More than 40% are

Vulnerable and Endangered to Critically endangered [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF]. Most cartilaginous fish populations can tolerate only modest levels of fishing without reduction and stock collapse [START_REF] Camhi | Sharks and their relatives -Ecology and Conservation[END_REF]Musick, 1999a;[START_REF] Cortés | Life History Patterns and Correlations in Sharks[END_REF]. Their low fecundity, late maturity and slow growth rates make them vulnerable to fishing [START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF]. Cartilaginous fish, especially elasmobranchs, present a number of reproductive strategies. All elasmobranchs fertilize internally and produce a relatively small number of large eggs. Elasmobranch fecundity generally ranges from one to two offspring produced a year up to a maximum of 300 in the whale shark [START_REF] Compagno | Alternative life-history styles of cartilaginous fishes in time and space[END_REF][START_REF] Joung | The whale shark, Rhincodon typus, is a livebearer: 300 embryos found in one ‗megamamma'supreme[END_REF]. Such characteristics have serious consequences for cartilaginous fish populations; limiting their capacity to withstand fisheries and recover from declines [START_REF] Camhi | Sharks and their relatives -Ecology and Conservation[END_REF][START_REF] Cailliet | Ecology and Life History Characteristics of Chondrichthyan Fish. In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF].

The Eastern Mediterranean, according to the United Nations Food and Agriculture Organization, consists of all waters from the Aegean Sea (following the coasts of Turkey and Greece) eastward towards the Levantine basin (following the coasts of Turkey and other countries of the Eastern Mediterranean and across the northern entrance to the Suez Canal and along the coast of Egypt) (FAO, 2004) (Figure 18). The Eastern Mediterranean has a lower species diversity and poorer nutrients compared to the Western Mediterranean [START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF]. It is the most oligotrophic part of the Mediterranean [START_REF] Azov | Eastern Mediterraneana Marine Desert?[END_REF]. Many studies on cartilaginous fishes were performed in the eastern Mediterranean with more than 100 papers ranging from the coasts of Alexandria -Egypt in the South, passing through the coasts of Israel, Lebanon, Syria, Turkey and reaching the Aegean Sea in the North [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF].

This study reviews the cartilaginous fishes status in the Eastern Mediterranean based on all the studies published in the latter region summarizing the inventories and studies in order to reflect the presence of this fish class and its life history traits in the eastern region of the Mediterranean.

The following sections describe the various studies that have been carried out on cartilaginous fish species in the Eastern Mediterranean: cartilaginous fish inventories, observations and first records, fishing and conservation, age and growth patterns, length-weight relationships, reproduction and nutrition.

The cartilaginous fishes of the Levantine Basin and Aegean Sea

Cartilaginous fishes of the Eastern Mediterranean have been mentioned in several field identification guides since 1987 [START_REF] Fischer | Fiches FAO d'identification des espèces pour les besoins de la pêche. Méditerranée et mer Noire. Zone de Pêche[END_REF][START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF][START_REF] Golani | Fishes of the eastern Mediterranean: Turkish Marine Research Foundation[END_REF][START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF]. However, several inventories on cartilaginous fish species in the Eastern Mediterranean were carried out in studies in several Eastern Mediterranean countries.

An inventory was established in Syria by [START_REF] Ali | A qualitative, economical, and biological study of cartilaginous fish in Syrian marine waters[END_REF] and [START_REF] Saad | Liste commentée des Chondrichthyens de Syrie (Méditerranée orientale)[END_REF] reflecting the presence of 37 cartilaginous fish species along the Syrian coasts, after reporting 22 species in 2003 [START_REF] Ali | Sharks and rays in Syrian sea waters (in Arabic with abstract in English)[END_REF]. Only one work was previously established during the past century [START_REF] Gruvel | Les Etats de Syrie : richesses marines et fluviales : exploitation actuelle, avenir[END_REF] in which the presence of 15 cartilaginous species was reported along the Syrian coast.

The presence of cartilaginous fish species has also been reported in Cyprus. A total number of 28 species of sharks and dogfish and 17 species of skates and rays have been listed in a paper by [START_REF] Hadjichristophorou | Chondrichthyes in Cyprus[END_REF]. The main sources of information, from which the Cypriot inventory was established, were [START_REF] Demetropoulos | The Fishes and Crustaceans of Cyprus: Ministry of Agriculture and Natural Resources[END_REF], [START_REF] Gilat | On the sharks and fishes observed using underwater photography during a deep-water cruise in the eastern Mediterranean[END_REF]Gelman (1984), Fischer et al. (1987), [START_REF] Compagno | Part 1 -Hexanchiformes to Lamniformes[END_REF], Compagno (1984b), McEachran and Capapé (1984a) andSerena (2005a).

Fish biodiversity in Lebanon was studied by [START_REF] George | The Fishes of the Coastal Waters of Lebanon[END_REF], [START_REF] George | On the occurrence Scomberomorus commerson (Lacépède) in St George Bay, Lebanon[END_REF], George and Athanassiou (1966a), George and Athanassiou (1966b), George and[START_REF] George | A two year study of the fishes appearing in the seine fishery of St George Bay[END_REF][START_REF] George | The presence of a third species of the genus Sphyraena (Pisces) in the marine water waters of Lebanon[END_REF], recording a list of 44 cartilaginous fish species and 313 bony fish species. An updated list was established by [START_REF] Boulos | Contribution à l'océanographie des pêches au Liban[END_REF]. Later, cartilaginous fish species were mentioned by [START_REF] Mouneimne | Liste des poissons de la côte du Liban (Méditerranée orientale)[END_REF], [START_REF] Mouneimne | Poissons des côtes du Liban (Méditerranée Orientale)[END_REF] and [START_REF] Mouneimne | Poissons nouveaux pour les côtes libanaises[END_REF].

However, the most recent inventory was established by [START_REF] Mouneimne | Poissons marins du Liban et de la Méditerranée Oriental[END_REF] Cartilaginous fish species found in Israeli waters were also listed in many initial and revised studies [START_REF] Ben-Tuvia | Mediterranean fishes of Israel[END_REF][START_REF] Ben-Tuvia | Revised list of the Mediterranean fishes of Israel[END_REF]. A general study of marine ichthyofauna in the eastern Levant was then presented by [START_REF] Golani | The marine ichthyofauna of the eastern levant-history, inventory, and characterization[END_REF]. Later, an updated list was compiled in [START_REF] Golani | Cartilaginous fishes of the Mediterranean coast of Israel[END_REF] stating that the Mediterranean ichthyofauna of Israel includes a total of 57 cartilaginous species: 31 sharks, 25 skates and rays and only a single chimaera species; only one species Himantura uarnak (Gmelin, 1789) is a lessepsian migrant of Red Sea.

Turkish ichthyofauna was more strongly studied during the 20th century, where an overall picture was obtained by notable surveys carried Aegean Sea [START_REF] Geldiay | Izmir Körfezinin başlıca balıkları ve muhtemel invasionları[END_REF] and Levantine Sea [START_REF] Akyuz | Observations on the Iskenderun red mullet (Mullus barbatus) and its environment[END_REF]. Later, nine cartilaginous fish species were recorded in Edremit Bay (Aegean Sea) during 1996 and 1997 [START_REF] Torcu | A Study on the Fishes of Edremit Bay (Aegean Sea)[END_REF], three in Saros Bay (North Aegean Sea) during 1999 and 2000 [START_REF] Torcu-Koc | An investigation on fishes of Saros Bay (Northern Aegean Sea) Balıkesir Üniversitesi Fen Bilimleri Enstitüsü Dergisi[END_REF], and 15 in Bozcaada Island (North Aegean Sea) during 2000 and 2001 [START_REF] Eryilmaz | A study on the fishes of Bozcaada Island (North Aegean Sea)[END_REF]. Some publications dealing with the fishes of the Aegean Sea are those by [START_REF] Kosswig | The Hydrobiological Research Institute of Istanbul University and its work[END_REF], [START_REF] Aksiray | Turkiye Deniz Balıkları Tayin Anahtarı[END_REF], [START_REF] Tortonese | Leptocardia, Ciclostomata, Selachii, Fauna d'Italia[END_REF], [START_REF] Demir | Marmara ve Kuzeydogu Ege'den un derin deniz baligi nev'i[END_REF], [START_REF] Bini | Atlante dei pesci delle coste italiane[END_REF], [START_REF] Tortonese | Fauna d'Italia. In Osteichthyes (Pesci ossei)[END_REF], [START_REF] Aksiray | Tiirkiye Deniz Bahklan Ve Tayin Anahtan[END_REF], [START_REF] Papaconstantinou | Fauna Graeciae: Check-list of Marine Fishes of Greece[END_REF], [START_REF] Papaconstantinou | The demersal fish fauna of the North and West Aegean Sea[END_REF], Mater and Meric (1996), [START_REF] Meric | 'den ele gecirilen bazi baliklar[END_REF], [START_REF] Torcu | Lessepsian fishes spreading along the coasts of the Mediterranean and the southern Aegean Sea of Turkey[END_REF], and [START_REF] Mater | Türkiye Omurgalılar Tür Listesi[END_REF].

Moreover, a study performed by [START_REF] Kabasakal | Elasmobranch species of the seas of Turkey[END_REF], based on field surveys and reviews of available literature, revealed the presence of 69 elasmobranch species representing 21 families along the coasts of Turkey. In fact, [START_REF] Kabasakal | Shark captured by commercial fishing vessels off the coast of Turkey in the northern Aegean Sea[END_REF] documented 20 species of sharks representing 11 families and 5 orders in the coasts of the northeastern Aegean Sea; these sharks were caught by commercial fishing vessels, in particular, trawlers. Besides, a prior study conducted in Iskenderun Bay between December 1994 and November 1996 exposed the presence of 19 cartilaginous fish species in that region [START_REF] Basusta | A study on the pelagic and demersal fishes in Iskenderun Bay (in Turkish with English abstract)[END_REF]. More recently, a checklist was done by [START_REF] Bilecenoglu | Checklist of the Marine Fishes of Turkey[END_REF] comprising the marine ichthyofauna, including cartilaginous fish species, of the Aegean and Levantine Seas. Later, an updated list was presented by [START_REF] Bilecenoglu | An updated checklist of the marine fishes of Turkey[END_REF] reflecting the occurrence of cartilaginous fish species in the Aegean and Levantine Seas of the Eastern Mediterranean.

The species caught or observed in the Eastern Mediterranean are presented in this section and summarized in Table 7. The most recent inventory in Lebanon was established during the research events of this thesis.

A total of 25 cartilaginous fish species were recorded during this study. Table 8 represents the most recent Lebanese inventory along with the native distribution of these species according to FishBase (2015). The native distribution maps for each of the 25 species recorded along the Lebanese coast were downloaded from AquaMaps (2013) and presented in ANNEX VI.

Table 8: The 25 cartilaginous fish species recorded along the Lebanese coast during this study along with their native distribution according to FishBase (2015). When no detailed information was available for the distribution of the sub regions, the cells were merged. No sub regions were specified for the Pacific and Indian Oceans. * The species also recorded in Lebanon between 1973and 1983[START_REF] Mouneimne | Poissons marins du Liban et de la Méditerranée Oriental[END_REF]

Cartilaginous fish observations and first records in the Eastern

Mediterranean

Knowledge of the biology, ecology and records of cartilaginous fish along the coast of Lebanon is almost absent. Only the inventories mentioned previously reflect the presence of this fish class in the Lebanese waters.

Syria

Along the Syrian coast, however, several papers based on cartilaginous fish first records were established. A first record of the Basking Shark, Cetorhinus maximus (Gunnerus, 1765) off the coast of Syria was noted in 2012 by [START_REF] Ali | Occurence of Basking Shark, Cetorhinus maximus (Elasmobranchii: Lamniformes: Cetorhinidae), off the Syrian coast (Eastern Mediterranean) with first description of egg case[END_REF]. The specimen was a pregnant female (L T =690 cm) containing 34 egg cases. Later in 2013, a Round Fantail Stingray, Taeniura grabata (Geoffroy Saint-Hilaire, 1817) off the Syrian coast was first recorded by [START_REF] Ali | First records of the Round Fantail Stingray, Taeniura grabata (Chondrichthyes: Dasyatidae), off the Syrian coast (eastern Mediterranean)[END_REF]. As for the Red Sea migrant, Himantura uarnak, it was first recorded along the Syrian coast in 2010 [START_REF] Ali | First records of the Honeycomb Stingray, Himantura uarnak (Forskål, 1775), off the Syrian coast (eastern Mediterranean) (Chondrichthyes: Dasyatidae)[END_REF]. Another Red Sea migrant, Torpedo sinuspersici (Olfers, 1831) was recorded along the Syrian coast by [START_REF] Saad | Liste commentée des Chondrichthyens de Syrie (Méditerranée orientale)[END_REF].

Israel

The studies on the biology and ecology of cartilaginous fish along the coast of Israel are not so common. There have been a few studies on Centrophorus granulosus (Bloch & Schneider, 1801) and other deep-water species [START_REF] Gilat | On the sharks and fishes observed using underwater photography during a deep-water cruise in the eastern Mediterranean[END_REF][START_REF] Pisanty | Vertical distribution of demersal fish on the continental slope of Israel. In Condition of the world aquatic habits[END_REF][START_REF] Golani | Biological aspects of the Gulper shark, Centrophorus granulosus, from the Mediterranean coast of Israel[END_REF] and several taxonomical studies [START_REF] Baranes | Taxonomy and behaviour of the genera Mustelus and Triaenodon (Triakidae, Pisces) of the Mediterranean and Red Sea[END_REF][START_REF] Goren | New records of deep-sea fishes from the Levant basin and a note on the deep-sea fishes of the Mediterranean[END_REF].

Moreover, several studies on cartilaginous fish observations and first records were also at a depth of 1440 m, which increased its bathymetric range. More recently, two studies noted the first record of Dasyatis chrysonota (Smith, 1828) [START_REF] Golani | First record of the Blue stingray, Dasytis chrysonota (Smith, 1828) (Chondrichthyes: Dasyatidae), off the coast of Israel (eastern Mediterranean)[END_REF] and the second record of Mobula mobular (Bonnaterre, 1788) [START_REF] Golani | New records and rare occurrences of fish species from the Mediterranean coast of Israel[END_REF] along the Mediterranean coast of Israel.

Turkey

Several studies on cartilaginous fish first records and observations were established in the Mediterranean Turkish and Aegean Seas. In 1996, an accurate recording of five Etmopterus spinax (Linnaeus, 1758) specimens was presented by [START_REF] Kabasakal | Observations on Etmopterus spinax (Pisces: Squalidae), from the north-eastern Aegean Sea[END_REF] in the Gulf of Saros (Northeastern Aegean Sea). The presence of this species in the seas of Turkey has been recorded by [START_REF] Aksiray | Tiirkiye Deniz Bahklan Ve Tayin Anahtan[END_REF]with vague information about depth and locality. [START_REF] Kaya | An investigation on the deep sea fishes of the Aegean Sea[END_REF] reported only one specimen of E. spinax from the Gulf of Gokova (Southeastern Aegean Sea) at a depth of 730 m. Moreover, a Bigeye Thresher Shark (L T =350 cm), Alopias superciliosus (Lowe, 1841) was recorded for the first time in the latter gulf in May 2005 [START_REF] Kabasakal | On the occurrence of the bigeye thresher shark, Alopias superciliosus (Chondrichthyes: Alopiidae), in Turkish waters[END_REF]. A male Shortfin Mako, Isurus oxyrinchus (Rafinesque, 1810) was also recorded in the Gulf of Saros for the first time in 2012 by a commercial fisherman using a hook and a line [START_REF] Kabasakal | First record of a shortfin mako shark, Isurus oxyrinchus Rafinesque, 1810 (Chondrichthyes: Lamnidae) from the Bay of Saroz (NE Aegean Sea)[END_REF]. Furthermore, a study in 2008 in the Aegean Sea presented the smallest neonate Great White Shark, Carcharodon carcharias (Linnaeus, 1758), from the Mediterranean waters to [START_REF] Kabasakal | Two new-born great white sharks, Carcharodon carcharias (Linnaeus, 1758) (Lamniformes; Lamnidae) from Turkish waters of the north Aegean Sea[END_REF]. The latter study recorded the capture of a new born Great White Shark by a commercial gill-netter in the coast of Altinoluk (Edremit Bay, North Aegean Sea) prior to the capture of a juvenile by the bottom long liner of the same fisherman. Besides, 12 individuals of C. carcharias were either recorded or sighted in Aegean waters from 1957 to 2011 [START_REF] Kabasakal | The status of the great white shark (Carcharodon carcharias) in Turkey's waters[END_REF]. Captures of the Bluntnose Sixgill Shark, Hexanchus griseus (Bonnaterre, 1788), from 1967 to 2013 by commercial fisheries in the Mediterranean and Aegean Seas of Turkey were also recorded in [START_REF] Kabasakal | Bluntnose sixgill shark, Hexanchus griseus (Chondrichthyes: Hexanchidae), caught by commercial fishing vessels in the seas of Turkey between 1967 and 2013[END_REF]. First record studies were maintained in the Turkish Mediterranean seas, especially in the northeastern part. A Red Sea migrant, Himantura uarnak, and a Round Fantail Stingray, Taeniura grabata were first recorded in May 1997 in Iskenderun Bay at depths of 15 and 20 m respectively [START_REF] Basusta | Two new records for the Turkish seas: Round stingray Taeniura grabata and skate stingray Himantura uarnak (Dasyatidae)[END_REF]. Almost during the same period of time, a Speckled Ray, Raja polystigma (Regan, 1923) was also recorded for the first time in the Mediterranean seas of Turkey [START_REF] Kabasakal | The first record of the speckled ray, Raja (Raja) polystigma Regan, 1923 in the seas of Turkey[END_REF]. In addition, four accidental captures of C. maximus in the coastal waters of Antalya and Mersin Bays (Eastern Mediterranean) were documented since 1987 [START_REF] Kideys | Occurrence of the basking shark, Cetorhinus maximus in the northern Levantine, the eastern Mediterranean[END_REF]Kabasakal, 2002a).

Besides, small groups of this shark have been sighted by [START_REF] Kideys | Occurrence of the basking shark, Cetorhinus maximus in the northern Levantine, the eastern Mediterranean[END_REF] in Mersin Bay near Edremli in 1996. On 30 December 2006, C. maximus (L T = 300 cm) was also incidentally caught by a stationary net set in the coastal waters of İskenderun Bay; and on 7 April 2012, a male of the same species has been incidentally caught by a coastal gill-netter just 50 m off Erdemli coast [START_REF] Bilecenoglu | New Mediterranean Marine biodiversity records[END_REF]. Furthermore, a Sawback Angelshark Squatina aculeata (Cuvier, was also recorded in Iskenderun Bay in February 2014 [START_REF] Kapiris | New Mediterranean Biodiversity Records[END_REF] after 30 years from its capture between 1980 and 1984 by [START_REF] Gucu | Trawlable species assemblages on the continental shelf of the Northeastern Levant sea (Mediterranean) with an emphasis on Lesseptian migration[END_REF] in the same region. In addition, the smallest individual of I. oxyrinchus (L T = 69.8 cm) was caught by a purse seine boat in March 2010 at a 54 m depth off the Samamdag coast of Iskenderun Bay [START_REF] Bilecenoglu | New Mediterranean Marine biodiversity records[END_REF].

Finally, during the last 58 years only 12 Angular Rough Sharks, Oxynotus centrina (Linnaeus, 1758) have been recorded in Turkish waters; three of these were recorded in the Aegean Sea and one in Levantine waters [START_REF] Kabasakal | Historical and contemporary records of the angular rough shark Oxynotus centrina (Chondrichthyes; Oxynotidae) in Turkish waters[END_REF]. Recently, a gravid female of O. centrina and an adult male were recorded in the northeastern Mediterranean, indicating that there is a nursery area in the region, where mating might probably occur [START_REF] Basusta | New records of gravid female and adult male of the angular rough shark, Oxynotus centrina (Oxynotidae) from the northeastern Mediterranean[END_REF].

Cartilaginous fishing in the Eastern Mediterranean

Assessing Mediterranean elasmobranch fishing is an important issue and it applies to all its basins. Elasmobranch fish catches constitute 1.1% of the total landings in Mediterranean Sea [START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF]. About half of the estimated global catch of elasmobranch species is bycatch and not disclosed in official fishery statistics [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF]. Discards constitute over 40% of the catch [START_REF] Sánchez | Characterisation of the discards generated by bottom trawling in the northwestern Mediterranean[END_REF]. Bycatch can induce imbalances between top predators and prey and consequently affect biodiversity [START_REF] Hall | Bycatch: problems and solutions[END_REF].

The major elasmobranchs fishing countries within the Mediterranean are Italy, Turkey and Tunisia. There are no fisheries directed to elasmobranchs in the Mediterranean and elasmobranchs are part of the bycatch in most local artisanal fisheries [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF].

However, [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF] indicated that there is a low fin trade share in the Mediterranean (i.e. Tunisia).

Juvenile bycatch of commercial species may harmfully affect the future stock and catch levels [START_REF] Hall | Bycatch: problems and solutions[END_REF]. Nevertheless, the bycatch of endangered species such as marine mammals, seabirds, turtles and elasmobranchs can have troublesome ecological consequences. These groups of species are susceptible due to their specific biological characteristics [START_REF] Musick | Management of sharks and their relatives (Elasmobranchii)[END_REF][START_REF] Gilman | Shark interactions in pelagic longline fisheries[END_REF], especially elasmobranchs that are characterized by their slow growth rate, late maturity and low fecundity compared to bony fish.

Trawling is considered responsible for a large amount of elasmobranch bycatches and discards throughout the world [START_REF] Bonfil | Trends and patterns in world and Asian elasmobranch fisheries[END_REF]. Trawling is prohibited along the coast of Lebanon, in the Levantine Basin of the Eastern Mediterranean [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF]. This method is problematic and leads to juvenile catches, important discards and negative impact on the environment [START_REF] Sacchi | Impact des techniques de pêche en Méditerranée : Solutions d'amélioration[END_REF]. There is no fishery targeting elasmobranchs, but all species are mainly caught by this fishing gear; 62 species are listed in the trawl fisheries in Greece, 62 in Catalonia and 74 in Italian waters [START_REF] Bertrand | Contribution on the distribution of the Elasmobranchs in the Mediterranean Sea (from the MEDITS Surveys)[END_REF]. Nonetheless, demersal species are the most caught [START_REF] Baino | Catch composition and abundance of Elasmobranchs based on the MEDITS program[END_REF][START_REF] Massutí | Demersal assemblages and depth distribution of elasmobranchs from the continental shelf and slope off the Balearic Islands (western Mediterranean)[END_REF]. Trammel nets and gillnets are the most frequently used by small Mediterranean fisheries and there is a little use of gillnets targeting sharks [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF].

The impact of all fishing gear used in the Mediterranean on cartilaginous fish species was assessed in several papers. [START_REF] Tudela | Ecosystem effects of fishing in the Mediterranean: an analysis of the major threats of fishing gear and practices to biodiversity and marine habitats[END_REF] described demersal and pelagic fisheries separately giving the different species involved and the corresponding impacting activities. [START_REF] Sacchi | Impact des techniques de pêche en Méditerranée : Solutions d'amélioration[END_REF] evaluated 11 fishing methods, their impact on cartilaginous fish and solutions for improvement.

Bycatches and discards of sharks in the large pelagic fisheries in the Mediterranean Sea were assessed in a report by [START_REF] Megalofonou | Bycatches and discards of sharks in the large pelagic fisheries in the Mediterranean Sea[END_REF]. More recently, two papers analyzed the composition and abundance of the pelagic shark bycatch and estimated discards from Greek swordfish and tuna fisheries in the eastern Mediterranean Sea during the period from 1998 to 2001 [START_REF] Megalofonou | Composition and abundance of pelagic shark bycatch in the eastern Mediterranean Sea[END_REF]Megalofonou et al., 2005c). These papers showed that shark bycatches were notable in the swordfish fishery, with the most common species being the Blue Shark, Prionace glauca (Linnaeus, 1758). Moreover, higher abundance indices were observed in the Levantine Basin and low discards in the Aegean Sea. A later paper by [START_REF] Megalofonou | Modeling environmental, spatial, temporal, and operational effects on blue shark bycatches in the Mediterranean long-line fishery[END_REF] assessed the environmental, spatial, temporal, and operational effects on blue shark bycatches in the Mediterranean longline fishery by applying generalized linear model approaches.

Shark bycatch and discards were maintained in the Greek waters (Eastern Mediterranean) in a paper dealing with the Greek swordfish fishery [START_REF] Peristeraki | Bycatches and discards of the Greek swordfish fishery[END_REF]. In this paper, data on bycatches and discards of the Greek fleets targeting swordfish, collected by observers on board from 2004 to 2006 were analyzed. In terms of weight, the landed swordfish represented the 84% of the total catches, and shark bycatch represented 1.9%. Furthermore, regarding the same Greek swordfish fishery in the Eastern Mediterranean, spatio-temporal variations in shark bycatches were examined by [START_REF] Tserpes | Oilfish and shark bycatches of the Greek swordfish fishery in the eastern Mediterranean: a preliminary analysis applied to "presence-absence" data[END_REF] using Generalized Linear Modeling techniques applied to -presence-absence‖ data collected from 2000 to 2003. In the latter paper, the presence of sharks had a stable pattern, showing only significant monthly variations.

Finally, [START_REF] Ferretti | Bycatch of sharks in the Mediterranean Sea: available mitigation tools[END_REF] reviewed examples of bycatch mitigation tools available worldwide that would be effective for elasmobranchs particularly in the Mediterranean basin.

For instance, the latter mentioned technological methods by modifying the fishing gear, and legislative regulations to decrease wastage productions and protect endangered species, and social approaches by working with fishermen to adapt them to these types of work limits.

Age and growth

Age determinations based on the examination of hard anatomical parts is indispensable in fisheries research. Precise age information allows quality estimates of growth and other vital rates such as natural mortality and longevity, and is important for successful fisheries management. Fish age and growth also aid to evaluate many other biological (and pathological)

processes, such as productivity, yield per recruit, prey availability, habitat suitability and even feeding kinematics [START_REF] Devries | Determination of age and growth[END_REF][START_REF] Campana | Accuracy, precision and quality control in age determination, including a review of the use and abuse of age validation methods[END_REF][START_REF] Robinson | Patterns of growth and the effects of scale on the feeding kinematics of the nurse shark (Ginglymostoma cirratum)[END_REF].

Several studies on cartilaginous fish age and growth were performed in the Eastern

Mediterranean. One study dealt with the dying techniques of aging in Iskenderun Bay [START_REF] Basusta | Aging with alcian blue dying techniques for some elasmobranchs in Iskenderun Bay, eastern Mediterranean Rapports de la Commission[END_REF]. In the latter study, age determinations were carried out using vertebral sections and alcian blue dying techniques were used to improve the visibility of the band on vertebrae. This study concluded that the alcian blue staining technique can be used successfully for age determination of elasmobranchs vertebrae. Other studies on the biological characteristics of some elasmobranchs mentioned age estimates and ages at first maturity. For example, Megalofonou et al. (2005a) and Megalofonou et al. (2009a) estimated the age of P. glauca from caudal vertebrae to range from 1 to 12 years and estimated the age at 50% maturity as 4.9 years for males and 5.5 years for females using caudal vertebrae. Moreover, the oldest estimated age of a Roughtail Stingray, Dasyatis centroura (Mitchill, 1815), was also studied by Basusta and Sulikowski (2012) in Iskenderun Bay. In the latter study, a 24 years of age estimated from the vertebrae section was recorded for a large D. centroura from the Mediterranean Sea. The maximum age of the Longnosed Skate, Dipturus oxyrinchus (Linnaeus, 1758) was estimated by Yigin and Ismen (2010a) in Saros Bay, North Aegean Sea, to be 8 years for males and 9 years for females. More recently, the maximum age of the Rough Ray, Raja Radula (Delaroche, 1809) was estimated by [START_REF] Yigin | Age, growth and reproduction of the rough ray, Raja radula (Delaroche, 1809) in Saros Bay (North Aegean Sea)[END_REF] in to be 6 years for males and 8 years for females in the same region.

Among the several models and variations of models estimating growth parameters in fishes, the Von [START_REF] Bertalanffy | A quantitative theory of organic growth (Inquiries on growth laws. II)[END_REF] growth model is the most commonly applied. The Von Bertalanffy growth function has been introduced into fisheries by [START_REF] Beverton | On the Dynamics of Exploited Fish Populations[END_REF] and has been broadly used since then. Although it has been criticized over the years, it is the most widely used growth function in fisheries biology today [START_REF] Roff | The evolution of life histories: theory and analysis[END_REF][START_REF] Haddon | Modeling and quantitative methods in fisheries[END_REF]. Modeling growth is based on the principle that the size of an organism depends on the result of anabolism and catabolism. Furthermore, it is suitable to use and allows easy comparison between populations and several different forms of the model can be fitted to the age-length data. Several studies on elasmobranch age and growth using the Von Bertalanffy growth model were performed in the Eastern Mediterranean. Age and growth data for six cartilaginous fish species of the Eastern Mediterranean are presented in this section and include parameters for the Von Bertalanffy growth model providing estimates of L∞, the asymptotic or maximum length (or width for some batoids), k, the growth coefficient, and t 0 , the age or time when length theoretically equals zero ( Table 9).

Length-weight relationships

Size relationships and conversions (i.e. length-weight relationships) are considered as basic for fish stock assessment. These relationships are significant to understand the rate of growth, age, and other constituents of population dynamics [START_REF] Kolher | Length-weight relationships for 13 species of sharks from the western North Atlantic[END_REF]. Such relationships aid in deriving the weight estimates of fish from their lengths. They have been estimated for cartilaginous fish species throughout the Mediterranean, with several studies concentrated in its eastern part. They can be used to induce laws to limit the overexploitation of these fishes through direct fishing and bycatch by establishing a minimum catch weight limit and abiding to these weights when the lengths are estimated at sea.

This section presents the length-weight relationships of several cartilaginous fish species mentioned in studies performed in the Eastern Mediterranean (Table 10).

Reproductive aspects and biological indices

Assessing the reproductive aspects and biological indices in cartilaginous fish plays a vital role in determining the age at first maturity, mating and parturition time, and probable nursery areas.

This information can aid in thoroughly understanding the life history characteristics of elasmobranchs that is essential for their proper management because these fishes are particularly susceptible to anthropogenic threats. Essential life history characteristics needed for proper management include age/size at maturity, gestation length, and reproductive cyclicity [START_REF] Walker | Management measures[END_REF]2005). When this information is incorporated into fisheries models and species assessments, insight can be gained into when, where, and how often populations are reproducing, which can ultimately aid in reducing their decrease through the development of management protocols that improve fishery practices [START_REF] Walker | Management measures[END_REF]2005). This section presents the numerous studies that mention the reproductive aspects of several species of sharks and batoids in the Eastern Mediterranean.

Sharks

Several studies in the Eastern Mediterranean consisted of the biological and reproduction characteristics of 8 sharks in the region.

 Scyliorhinus canicula (Linnaeus, 1758)

Four studies on the biology and reproductive aspects of this shark species were done in the Eastern Mediterranean. [START_REF] Erdogan | Sexual dimorphism in the small-spotted catshark Scyliorhinus canicula (L, 1758), from the Edremit Bay (Turkey)[END_REF] analyzed the morphometric characteristics and dentition of 100 S. canicula specimens in Edremit Bay (Northern Aegean Sea) in 1998. These authors established that sexual dimorphism exists for this species and males have longer and narrower mouths than females.

Moreover, significant differences were recorded in the girth of the head and preoral, prebranchial head and body lengths.

In addition, sexual dimorphism was also recorded for the same species in Izmir Bay (Aegean Sea, Turkey) (Filiz and Taskavak, 2006b). The latter study was performed on 296 specimens of S. canicula between September and November 2002. It demonstrated pronounced sexual dimorphism where males showed to have longer and narrower mouths than females. Head and body measures also significantly differed between sexes.

Moreover, this species was mentioned in a study by [START_REF] Cakir | Some biological aspect of the lesser spotted dogfish Scyliorhinus canicula (Linnaeus, 1758) in Edremit Bay (The Northern Aegean Sea) Turkey[END_REF] in the northern Aegean

Sea. The latter study revealed that the reproduction activities of this species continued in all seasons with a relatively high rate of oogenesis in the summer and mature females spawned successively two eggs in each batch.

Finally, the sexual maturity and fecundity of S. canicula in the Aegean Sea were recently studied by [START_REF] Kousteni | Sexual maturity and fecundity of Scyliorhinus canicula (Linnaeus, 1758) in the Aegean Sea[END_REF]. These authors [START_REF] Kousteni | Sexual maturity and fecundity of Scyliorhinus canicula (Linnaeus, 1758) in the Aegean Sea[END_REF] demonstrated the size at 50% maturity of this species to be 396 mm and 399 mm for males and females, respectively. This study also evaluated ovary weight, oocyte diameter and fecundity for female specimens with an ovarian fecundity reaching a maximum of 18 ripe oocytes in the ovary of a 460 mm female. Only one pair of egg cases was found in each one of the 30 adult females examined. It finally showed significant seasonal variations in the gonado-somatic index of females.

 Centrophorus granulosus (Bloch and Schneider, 1801)

The reproductive biology of the Gulper Shark, Centrophorus granulosus, was evaluated by two studies in the Eastern Mediterranean. [START_REF] Golani | Biological aspects of the Gulper shark, Centrophorus granulosus, from the Mediterranean coast of Israel[END_REF] studied this species from September 1982 to November 1992 along the Mediterranean coast of Israel at depths of 200-1400 m. The population studied consisted mainly of females and gravid females had only one embryo or a single large egg. More recently, the reproductive aspects of C. granulosus were mentioned in a study by [START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF] on 43 specimens caught with bottom long lines off the island of Crete between 350-480 m depth. Most of the specimens in the latter study were mature with high gonado-somatic indices (females: 0.1-8.9; males 0.1-2.2). The unique gravid female found had only one large candle ovum in its right uterus.

 Hexanchus griseus (Bonnaterre, 1788) Rare are the studies evaluating the reproductive aspects of the Bluntnose Sixgill Shark, Hexanchus griseus, in the Eastern Mediterranean. However, eleven specimens of H. griseus were mentioned in a study by [START_REF] Kabasakal | Preliminary observations on the reproductive biology and diet of the Bluntnose sixgill shark, Hexanchus griseus (Bonnaterre, 1788) (Chondrichthyes: Hexanchidae), in Turkish Seas[END_REF] in the Aegean Sea. Biological examinations and available information in this study suggested that H. griseus gives birth from October to the end of February in the northern Aegean Sea. Furthermore, a more recent study by [START_REF] Kabasakal | Distribution and biology of the bluntnose sixgill shark, Hexanchus griseus (Bonnaterre, 1788) (Chondrichthyes: Hexanchidae), from Turkish waters[END_REF] determined the maturity states of the H. griseus specimens captured mostly between September and March, with two young specimens captured at depths less than 75 m.

 Dalatias licha (Bonnaterre, 1788)

One study mentioning some reproductive aspects of the Kitefin Shark, Dalatias licha, was done in the Eastern Mediterranean, specifically in the northern Aegean Sea. This study by [START_REF] Kabasakal | Morphometrics of young kitefin sharks, Dalatias licha (Bonnaterre, 1788), from northeastern Aegean Sea, with notes on its biology[END_REF] evaluated biological information on three neonate and two post-neonate D.

licha specimens captured in October 1999 of the northern coast of Gokgeada (Northeastern Aegean Sea) at a depth of 380 m. This study deduced from the capture of these specimens that this region might be a nursery area for this species.

 Squalus blainville (Risso, 1827)

One study was also performed on the reproductive biology and embryonic development of S.

blainville in the Eastern Mediterranean. This study by [START_REF] Kousteni | Reproductive biology and embryonic development of Squalus blainvillei in the eastern Mediterranean Sea[END_REF] evaluated 526 specimens of S. blainville that were sampled from the bottom trawl and bottom longline catches from December 2004 to December 2009. The males in this study reached sexual maturity at smaller sizes than females. The smallest sexually mature female was 523 mm in total length, while the smallest sexually mature male was 425 mm in total length. The length at 50% maturity was estimated to be 564.4 mm for females and 457.7 mm for males. The high gonado-somatic index of the specimens in the sample and the presence of sexually mature specimens of both sexes in every season of the year indicated a continuous reproductive cycle. This study also suggested that females ovulate after parturition because females carrying near-term embryos had large, equally developed ovarian oocytes.

 Squalus acanthias (Linnaeus, 1758)

The reproductive biology and embryonic development of the Spiny Dogfish, Squalus acanthias, were investigated by [START_REF] Chatzispyrou | Sexual maturity, fecundity and embryonic development of the spiny dogfish, Squalus acanthias, in the eastern Mediterranean Sea[END_REF] in the Aegean Sea, Eastern Mediterranean. In the latter study, 180 specimens of S. acanthias were studied; the gonado-somatic index and hepatosomatic index were higher during June and August in females, respectively; in males the gonadosomatic index peaked in July and the hepato-somatic index showed its highest value in April. A total of 39 gravid females were identified out of which 28 were bearing embryos. Ovarian and uterine fecundity ranged between 1 and 6 and the size of the pups varied from 72 to 220 mm total length and their weight ranged between 1.6 and 48.5 g.

 Oxynotus centrina (Linnaeus, 1758) Some embryonic characteristics of the Angular Rough Shark, Oxynotus centrina were mentioned by [START_REF] Megalofonou | Morphological and biological characteristics of a gravid angular rough shark (Oxynotus centrina) and its embryos from the eastern Mediterranean Sea[END_REF] in the Eastern Mediterranean. In this study, the authors recorded a gravid female in the Aegean Sea and characterized its 15 embryos. They all had a distinguishing coloration of darker marks on a light brownish background and were attached to sizeable yolk sacs but showed differences in development. Some had already absorbed a significant part of yolk sac content, while others had not. All embryos had clearly formed external morphological characteristics, similar to the adult stage and their sex was difficult to identify because no sign of clasper formation was observed.

 Prionace glauca (Linnaeus, 1758)

The reproductive characteristics of the Blue shark, Prionace glauca, were also mentioned in two studies about Blue Sharks sampled from the swordfish and tuna fishery in the Mediterranean Sea during the four-year period from 1998 to 2002 (Megalofonou et al., 2005a;Megalofonou et al., 2009a). The gonad observation of the sharks in the latter studies revealed that females smaller than 120 cm total length had immature ovaries with no mature oocytes, while females larger than 203 cm total length had mature ovaries with visible yolky oocytes. All males smaller than 125 cm were immature while males larger than 187 cm were mature. The length at 50% maturity for the Blue Sharks studied was estimated to be 202.9 cm for males and 214.7 cm for females.

Batoids

The reproductive aspects and biological characteristics of 5 batoid species were also studied in the Eastern Mediterranean. These studies concentrated on the biological observations and reproductive cycles of these species.

 Rhinobatos rhinobatos (Linnaeus, 1758)

The reproductive aspects and biology of the Common Guitarfish, Rhinobatos rhinobatos, were most commonly studied in the Eastern Mediterranean. Three studies were done in Iskenderun Bay (Northeastern Mediterranean) and one along the coast of Alexandria (Southeastern Mediterranean).

In Iskenderun Bay, the length at 50% maturity of R. rhinobatos was mentioned in Ismen et al.

(2007b) to be 68 cm for males and 69 cm for females. Moreover, parturition was found to be in summer and the mean total length and mean weight of developed fetuses were 25.7 cm and 48.5 g, respectively. In the same region, [START_REF] Cek | Biological observations on the common guitarfish (Rhinobatos rhinobatos Linnaeus 1758) from Iskenderun Bay[END_REF] used histological examinations of the gonads and showed that R. rhinobatos exhibits a cystic mode of spermatogenesis and can be used as a model for biomedical and toxicological studies. Eight stages of maturation for females and seven stages of maturation for males were identified. The study also suggested that both sexes are reproductively active at different times of the year and the species exhibit lecithotrophic embryonic development. More recently in Iskenderun Bay, the maturity and reproductive cycle of R. rhinobatos was also investigated by [START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF]. Lengths at 50% maturity in the latter study were 70 cm and 86 cm for males and females, respectively. In addition, the gonadosomatic index peaked in May for females and in November for males, and the hepato-somatic index was found to fluctuate widely in males and females.

Regarding an older study in the Egyptian Alexandria waters, data on gonado-somatic index, maximum ovum diameter, size frequency of ova, and ovarian and uterine contents for 438 R.

rhinobatos specimens were analyzed on a monthly basis by [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF] and indicated a distinct seasonal reproductive cycle for this species. Lengths at 50% maturity were 87 and 70 cm for females and males, respectively. Ovarian egg size and male gonado-somatic index both peaked in July and August, indicating that mating occurred in summer, and females with full-term embryos were observed in late August, and parturition was followed immediately by ovulation. Ovarian fecundity ranged from 8 to 27 eggs per fish, whereas uterine fecundity ranged from 8 to 14 eggs or embryos per fish.

 Torpedo torpedo (Linnaeus, 1758) and Torpedo marmorata (Risso, 1810)

The reproduction and biology of these two batoids were only reflected in a study by [START_REF] Abdelaziz | Observations on the biology of the common torpedo (Torpedo torpedo, Linnaeus, 1758) and marbled electric ray (Torpedo marmorata, Risso, 1810) from Egyptian Mediterranean waters[END_REF] in the Egyptian Eastern Mediterranean waters (Southeastern Mediterranean). In this study, the sizes at maturity of T. torpedo and T. marmorata were 18 and 25.5 cm for males, respectively, and 22 and 35.5 cm for females, respectively. T. torpedo was shown to have a restricted breeding season whereas T. marmorata was shown to have a more extended reproductive cycle (probably breeding every two years). In both species, males were capable of mating every year. Individuals of T. torpedo mated between December and February, ovulated in March and April, and underwent parturition in late August and September after five to six months of gestation. Individuals of T. marmorata mated between November and January, ovulated between December and February, and underwent parturition the following December after 10 to 12 months of gestation. The embryo sizes ranged from 4.6 to 8.2 cm for T. torpedo and from 5.8 to 10.1 cm for T. marmorata. Finally, a strong correlation between ovarian and uterine fecundity and the length of the mother in both species was shown from these observations.

 Raja miraletus (Linnaeus, 1758)

The sexuality, reproduction and fecundity of the Brown Skate, Raja miraletus, were also studied in the Eastern Mediterranean by [START_REF] Abdelaziz | Sexuality, reproduction and fecundity of Raja miraletus (L) from the Mediterranean waters off Alexandria[END_REF] off the coast of Alexandria. This study showed that the males and females of this species reached sexual maturity at 28 cm and 30 cm total length, respectively. Furthermore, the authors showed that vitellogenic activity started in spring (May) and peaked in summer (June, July, August). The study also suggested that the rate of egg laying and vitellogenic activity was controlled by temperature, and indicated the presence of a linear relationship between size and fecundity.

 Dasyatis pastinaca (Linnaeus, 1758)

The reproduction of the Common Stingray, D. pastinaca, in the Eastern Mediterranean was only reflected in a study by [START_REF] Ismen | Age, growth, reproduction and food of common stingray (Dasyatis pastinaca L., 1758) in İskenderun Bay, the eastern Mediterranean[END_REF] in Iskenderun Bay, Turkey. The latter study revealed that the parturition time of D. pastinaca occurred during summer and total length at maturity was 43 cm and 46 cm for males and females, respectively.

Nutrition and feeding habits

The analysis of stomach contents has become a standard practice to study the feeding habits of fish [START_REF] Hyslop | Stomach contents analysis--a review of methods and their application[END_REF]. Stomach content analysis provides significant insight into fish feeding patterns, and the quantitative assessment of food habits is an important aspect of fisheries management. Precise description of fish diets and feeding habits also provide basic comprehension of trophic interactions in aquatic food webs. Diets of fishes represent a combination of many important ecological components that include behavior, condition, habitat use, energy intake and inter/intra specific interactions. A feeding habit study might help determine the most frequently consumed prey, the relative importance of various food items to fish nutrition and quantify the consumption rate of individual prey types. Several studies consisting of stomach content analyses have been performed in the Eastern Mediterranean. These studies, as well as, their general results are detailed in Table 11.

Other studies

Other studies involving diverse aspects in cartilaginous fish research were also performed in the Eastern Mediterranean. These studies included genetics, organ trace metal and muscle fatty acid content, infections, distributions, temporal variation and habitat selection of cartilaginous fish species in the area.

Genetics

Regarding the genetics field, [START_REF] Turan | Molecular systematic analyses of mediterranean skates (Rajiformes)[END_REF]

Muscle and organ content

Concerning muscle and organ content, two studies involving trace metal contents and one involving fatty acid contents were performed on cartilaginous fish in the Eastern Mediterranean.

Regarding trace metals, [START_REF] Hornung | Trace metal content in deep-water sharks from the eastern Mediterranean Sea[END_REF] mustelus, except one, the concentrations of total mercury were below the maximum permitted level, whereas mercury concentrations were above this limit in 81% of the S. acanthias samples.

Regarding the fatty acid contents, total lipid content and fatty acid composition were analyzed by [START_REF] Hornung | Distribution and composition of fatty acids in muscle lipids of inshore fish and deep water sharks from the eastern Mediterranean[END_REF] in muscles of deep water sharks (Centrophorus granulosus, Galeus melastomus). The study revealed that the fatty acid composition and lipid content of the two shark species were similar, and that there was no correlation between mercury concentration and fatty acid composition or lipid content in the muscle of the sharks.

Parasitic infections

In addition, one study dealt with the parasitic infections of the Common Guitarfish, Rhinobatos rhinobatos, in Iskenderun Bay [START_REF] Genc | Seasonal variation of Hysterothylacium aduncum infection in the common guitarfish, Rhinobatos rhinobatos, in Iskenderun Bay (Northeastern Mediterranean Sea) Turkey[END_REF] by evaluating the seasonal variations of the presence of an anisakid nematode Hysterothylacium aduncum (Rudolphi, 1802) in the digestive tract of the latter elasmobranch.

Sediment preferences

Another study, carried out in Babadillimani Bight, northeastern Mediterranean, related sediment structure to the occurrence of skates and rays inhabiting the region by evaluating sediment composition and the distribution of the most common rays and skates in the area [START_REF] Yeldan | Sediment structure and occurence of skates and rays inhabiting in Babadillimani bight located in northeastern Mediterranean[END_REF]. The study revealed that skates preferred slightly silty bottoms while rays were more densely distributed along the shallower areas and sandy silts.

Habitat selection

Furthermore, studies of cartilaginous fish habitat selection and spatial and temporal distribution patterns were also carried out in the Eastern Mediterranean. For instance, [START_REF] Keskin | Preliminary results on depth distribution of cartilaginous fish in the North Aegean Sea and their fishing potential in summer 2001[END_REF]

General conclusion

This bibliographic review focuses on all the studies on cartilaginous fish species carried out in the Eastern Mediterranean region. Many studies on cartilaginous fish species are rare or lacking in some regions of the Eastern Mediterranean, such as, Lebanon, where species of this fish class are targeted by fishermen or constitute part of the bycatch in most local artisanal fisheries and have different degrees of commercial significance. Several species of this fish class are exploited for their fins, skin, jaws, or meat, directly targeted by commercial or recreational fisheries, or incidentally caught as bycatch. Some countries generally report shark statistics without distinction between species or, worse still, the species are not recorded at all, and some even do not report statistics at all probably due to the lack of taxonomists or scientists and officials trained in monitoring and evaluating these species, with insufficient access to basic tools for shark identification (FAO, 2014). Therefore, DNA barcoding studies that are lacking in the region should be used to validate species identification and decrease problems related to misidentification.

Fishing can lead to phenotypic and genetic responses altering age, size at maturity, longevity, fecundity and egg size [START_REF] Rochet | Short-term effects of fishing on life history traits of fishes[END_REF][START_REF] Law | Fishing, selection, and phenotypic evolution[END_REF][START_REF] Hutchings | Life histories of fish[END_REF]. Hence, studies on life history traits (especially age and histological reproduction) should be enforced in the Eastern Mediterranean as a stimulant to manage the exploitation of these species by artisanal fisheries or commercial fisheries. Works are concentrated mainly in the western Mediterranean and papers on biologic parameters concern few species primarily in the western and central Mediterranean areas [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF]. In general, this review shows that Eastern Mediterranean studies are concentrated on the biology of these species and their ecology is not well known.

Works on life history traits are mainly concentrated in the Aegean Sea with a few and almost none in some parts of the Levantine basin. Some highly exploited species, such as, R. rhinobatos are presented in several studies in the Eastern Mediterranean. The Endangered IUCN status of this species could facilitate the funding for studies related to its conservation. However, other species, such as, C. granulosus, having a Vulnerable status are less studied and problems in their identification still exist. In addition, studies related to the overall organization, structure, and complexity of the group/population of sharks are also lacking in the region; however, studies such as that of Mourier (Mourier et al., 2013;Mourier and Planes, 2013) allow to highlight behavioral aspects of sharks. Furthermore, tagging studies also seem to be lacking in the region.

Life history parameters, stock status, behavioral and distribution patterns, and migration patterns can be provided by such studies. Tagging constitutes and important tool to fishery managers because it provides the ability to record the presence of a particular fish or group of fish in time and space by marking [START_REF] Rounsefell | Fishery scienceits methods and applications[END_REF]. Behavioral and distribution patterns, as well as migration patterns, can provide insight to the location of nurseries or breeding areas aiming to reduce exploitation of these top predators. In addition, few are the studies relating cartilaginous fish to abiotic factors (i.e. habitat structure, temperature, salinity, dissolved oxygen, tide, photoperiod, barometric pressure, pH etc.) and biotic factors (i.e. marine community distributions, species interactions etc.). Due to a decline in cartilaginous fish species landings and the increase in fishing effort in the Mediterranean [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF], such studies are important to be implemented to highlight the importance and enforce the protection of these top predators in the marine ecosystem. Marine ecologists need to recognize that each species of cartilaginous fish occupies a distinct niche within a particular community. Thus, important studies are necessary to properly clarify the role each cartilaginous fish species plays in a given community [START_REF] Compagno | Ecology of cartilaginous fish. In Chondrichthyes (cartilaginous fish, including sharks, rays and chaemeras) Iziko Museums of Cape Town[END_REF].

Protection is currently granted to cartilaginous fish species under various regional and international conventions, but generally few species are considered. However, more studies performed on these fish should help for a better protection, as well as, fisheries management and stock assessment of this fish class. Finally, the International Union for the Conservation of Nature (IUCN) clearly reveals the vulnerability of this fish group and the lack of data in certain regions of the Mediterranean. Therefore, research projects on systematics, genetics, general biology, and ecology and population dynamics of concerned species should be carried out, and essential and critical cartilaginous fish habitats should be identified. More legislations and control should be implemented on the landing and bycatch of this fish group aiming to reduce its exploitation.

Chapter IV

Mots clés:

Chondrichthyens; impact de la pêche; Bassin Levantin; variations spatio-temporelles

Introduction

The Mediterranean Sea is the largest and deepest bounded sea on earth. Connecting three continents, it constitutes a hotspot of terrestrial and marine biodiversity [START_REF] Bianchi | Marine biodiversity of the Mediterranean Sea: Situation, problems and prospects for future research[END_REF][START_REF] Myers | Biodiversity hotspots for conservation priorities[END_REF][START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. Despite constituting a small percentage (0.32%) of the global oceanic volume and surface area (0.82%), the Mediterranean Sea holds 17,000 (7%) of all known marine species and exhibits a high level of endemism [START_REF] Bianchi | Marine biodiversity of the Mediterranean Sea: Situation, problems and prospects for future research[END_REF][START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. Throughout history, this rich ecosystem has been distorted in many ways, especially by overexploitation and habitat loss which are the main human drivers of historical changes [START_REF] Lotze | Historical changes in marine resources, food-web structure and ecosystem functioning in the Adriatic Sea[END_REF]. In addition, pressures on these these ecosystems have increased exponentially since the Industrial Revolution with resulting advances in technology and a human population explosion [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF][START_REF] Lotze | Historical changes in marine resources, food-web structure and ecosystem functioning in the Adriatic Sea[END_REF]. Currently, habitat loss and degradation, pollution, overexploitation, eutrophication, introduction of invasive species, bycatch, and recently climate change, are the most important threats affecting a greatest number of organisms in the Mediterranean Sea, especially chondrichthyans [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]Coll et al., 2010;[START_REF] Costello | A census of marine biodiversity knowledge, resources and future challenges[END_REF]. The Mediterranean Sea is identified as one of the three main hotspots where the diversity of sharks and rays is particularly seriously threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. It holds 80 chondrichthyan species [START_REF] Compagno | Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes[END_REF][START_REF] Compagno | A Field Guide to the Sharks of the World[END_REF][START_REF] Serena | Field identification guide to sharks and rays of Mediterranean and Black Sea[END_REF], out of which 71 were assessed by the IUCN, where three are endemic and one is endemic threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. Bycatch, intensive fishing activities and pollution are severe threats for these species [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. The situation of cartilaginous fish (chondrichthyans) in the Mediterranean Sea is much more miserable than it is worldwide: 42% of the shark species are threatened in the region in comparison with 17% globally, thus, describing the Mediterranean as the most unsafe sea in the world for cartilaginous fishes [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF]. The fishery in Lebanon is artisanal and trawling is legally forbidden. The most common gear used are trammels, longlines, ‗roundhaul' nets and beach seines [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF]. Information about the diversity or distribution of cartilaginous fish species along the Lebanese coast is still currently lacking. The presence of these fish species have already been mentioned along the coast [START_REF] George | The Fishes of the Coastal Waters of Lebanon[END_REF][START_REF] Boulos | Contribution à l'océanographie des pêches au Liban[END_REF][START_REF] Mouneimne | Liste des poissons de la côte du Liban (Méditerranée orientale)[END_REF]; however, no direct specific studies about the diversity or distribution of these species have been carried out in Lebanon knowing that several species of this fish class are exploited in some regions along the coast. In addition, the eastern Mediterranean area lacks long term fishery monitoring and studies in different regions, especially the Lebanese coast. Few studies mentioning cartilaginous fish habitat selection and spatial and temporal distribution were carried out in the Aegean Sea [START_REF] Keskin | Preliminary results on depth distribution of cartilaginous fish in the North Aegean Sea and their fishing potential in summer 2001[END_REF][START_REF] Maravelias | Habitat selection and temporal abundance fluctuations of demersal cartilaginous species in the Aegean Sea (Eastern Mediterranean)[END_REF][START_REF] Tserpes | Distribution of relatively rare demersal elasmobranchs in the eastern Mediterranean[END_REF] and Iskenderun Bay [START_REF] Yeldan | Temporal changes in some Rajiformes species of cartilaginous fish (Chondrichthyes) from the west coast of İskenderun Bay (northeastern Mediterranean)[END_REF].

Spatial and temporal distribution and diversity of exploited populations can be determined via data from scientific surveys, records of commercial fisheries and fishermen catches. These are two complementary methods each with advantages and disadvantages. Scientific survey data is standardized and controlled with defined georeferenced points; it can provide an important reflection of the spatial distribution of the studied population. However, a survey conducted once a year can contain temporal gaps. Fishery and fishermen data, on the other hand, provide a good temporal (seasonal) coverage but a weak spatial one due to the fact that most of the Lebanese artisanal fishermen do not have GPS instruments. In addition, total catch information for the computation of Catch per Unit Effort (CPUE) can sometimes be lacking. CPUE is commonly calculated from fishery data as an abundance index. Therefore, these two methods can be used in a complementary way to provide a further reflection of the spatial, depth and seasonal distribution and diversity of this exploited fish class.

The present study uses cartilaginous fish data from the scientific CIHEAM PESCA-Libano project carried out with the involvement of the Ministry of Agriculture and the National Center for Marine Sciences -Lebanese National Council for Scientific Research (CNRSL) along with fishery and fishermen data. It aims to assess the depth, spatial and seasonal distribution of cartilaginous fish species by analyzing the variation of CPUE data from the survey and total weight data from fishery and fishermen catches. Moreover, it reflects the spatial and seasonal diversity of this fish class aiming to highlight their presence along the coast. This could lead to stimulating the protection and management of the exploited cartilaginous fish along the Lebanese coast.

Materials and Methods

Description of the scientific survey: CIHEAM PESCA-Libano

The Gillnets with mesh sizes of 26, 30 and 40 mm (of 1 km length connected together) were lowered at depths less than 100 m; trammel nets with mesh sizes of 22, 24, 26, 28 and 30 mm (of 1 km length connected together) were lowered at depths greater than 100 m. Longlines of size 5 hooks were lowered at randomly specified depths.

Six artisanal fishermen from six different ports in Lebanon distributed in the north, south and central regions of the country were hired to lower the gear at the hauls with the specified coordinates (Figure 19). The length of the vessels ranged from 8.75 to 11 m and their gross tonnage ranged from 2 to 3.7 tons. A global positioning system (GPS) was used to reach the right haul and depth was confirmed using a sonar. Nets were not loaded with bait; however, the hooks of the longlines were always loaded with bait from chopped fish, such as, herrings (Etrumeus teres), mackerels (Scomber scomber) or tunas (Euthynnus alletteratus). Cartilaginous fish collected from the survey were identified and date, type of gear, net meshes, coordinates and depth in each catch were noted.

Description of the fishery and fishermen data collection

The Lebanese fishing fleet is composed of small scale artisanal vessels less than 12 m in length and typical of many Mediterranean countries. Around 42 ports are distributed along the Lebanese coast. The main ones are distributed according to the governorates as follows: Tripoli and Batroun ports in the North, Ozaaii Port in Beirut, and Tyre and Sidon Ports in the South (Figure 19).

Data collection from fisheries and artisanal fishermen had been performed in two manners: a) Cartilaginous fish were collected from randomly hired fishermen throughout the Lebanese coast with the collaboration of the Lebanese National Council for Scientific Research (CNRSL) -National Center for Marine Sciences -to lower longlines at depths ranging from 30 to 600 m aiming to catch cartilaginous species.

b) Cartilaginous fish were collected from major fisheries visited periodically along the Lebanese coast. Fisheries were visited a minimum number of 5 times per month from December 2012 to October 2014, and data were collected when specimens were available. The main fishery visited was a principal one in Tripoli, where there are constant cartilaginous fish catches and where species of this fish class have a significant commercial value.

Regarding both manners of the latter data collection, the exact position of the data collected was not recorded because most of the Lebanese artisanal fishermen do not have GPS instruments; however, the depth was noted as observed by the professional fishermen.

Measures and biological parameters recorded after collection

The cartilaginous fish caught were identified according to the Field Identification Guide to the Living Marine Resources of the Eastern and Southern Mediterranean [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF] and Fishes of the Eastern Mediterranean [START_REF] Golani | Fishes of the eastern Mediterranean: Turkish Marine Research Foundation[END_REF]. Many morphometric and biological measurements were recorded prior to and after dissection; nevertheless, only few were considered in this study.

 Measurements considered for the scientific survey data

Total weight (W T ) was only used for the analyses of the scientific survey data. A total weight (less than five kilograms) was measured to the nearest gram (g) using an electric balance. A total weight greater than five kilograms was measured using a scale to the nearest 100 g.

 Measurements considered for fisheries and fishermen data

Along with total weight, sex of each specimen, and sexual maturity were used for the analyses of the fisheries and fishermen data. The sexual maturity of each specimen caught was determined by observing female and male gonads using gonad aspects as defined in the ‗Instruction Manual' of the MEDITS -International bottom trawl survey in the Mediterranean -Version 6 (MEDITS, 2012).

Computation of the abundance index, statistical analyses and cartography

Computation of the abundance index

The catch per unit effort (CPUE) was calculated for the cartilaginous species caught only during the CIHEAM-PESCA Libano survey using the statistical software R project (R Development Core Team, 2014) and was expressed in kilograms and in number according to the following:

1. CPUE in kilograms according to each meshed gear (Index G: gear; Index M: mesh) for trammel nets, gillnets, and longlines:

∑ T ⁄
where i is the cartilaginous species caught in a specific meshed gear or longline in the predetermined haul, N Ci,G,M the total number of cartilaginous species i caught in the same meshed gear or longline also in the predetermined haul, and E the effort which is considered one because each gear was lowered once with the same effort duration.

2. CPUE in number according to each meshed gear (Index G: gear; Index M: mesh) for trammel nets, gillnets, and longlines:

∑

where N Ci,G,M is the total number of the cartilaginous species i caught in a specific meshed gear or longline in the predetermined haul and E the effort which is considered one because each gear was lowered once with the same effort duration.

Factors impacting the abundance index of elasmobranch species

Permutational Multivariate Analysis of Variance (PERMANOVA)

PERMANOVA was performed on the matrix of CPUE in kilograms and number separately of the different cartilaginous species caught to test the influence of various factors (gear, region, depth, and season) in the scientific survey using the Euclidean method with 9999 permutations.

The considered factors were: gear: Gillnets, Long liners, Trammel nets; region: North, Central, South; depth: [0-200[, [200-400[, [400-600] in meters and seasons: Spring, Summer, Winter.

Regarding the fisheries and fishermen data, PERMANOVA was performed on the total weight of the different cartilaginous species caught according to the available factors for fisheries data (gear, region, depth, season, sex, and sexual maturity) using the same method with the same number of permutations. All factors were considered as fixed. The factor modalities of the PERMANOVA fisheries and fishermen data analysis were for gear: Gillnets, long liners, trammel nets; region: North, South; depth: [0-300[, [300, 600] in meters; seasons: Spring, Summer, Autumn, Winter; sex: Males and females and sexual maturity: Immature and mature individuals.

The data (CPUE in kilograms and number or total weight) were log transformed before the analyses into log(x+1) in order to homogenize the variances and normalize the distributions.

Both PERMANOVA analyses were performed using the adonis function of the ‗vegan' package on the statistical software ‗R project'(R Development Core Team, 2014) on shark, batoid and combined datasets with interaction of factors.

Canonical Correspondence Analysis (CCA)

A descriptive statistical method was also carried out to give further details to how the ordination

Maps and interpolation

The maps and interpolations were realized and performed on the Quantum Geographic Information System (qGIS) software (QGIS Development Team, 2012) only for the scientific survey data. Spatial interpolation was performed on the CPUE (expressed in kilograms and number) and species richness according to haul for the shark, batoid, and combined datasets using the Inverse Distance Weighting (IDW) method and the ‗Linear' color interpolation.

Biodiversity indices

Seasonal and spatial biodiversity were evaluated for the scientific survey and fishery and fishermen data combined by calculating several diversity indices according to [START_REF] Magurran | Measuring biological diversity: Blackwell Science[END_REF].

The Shannon Index (H'), Shannon evenness (Pielou's evenness: J'), Simpson Index (1-D), and taxonomic distinctness and diversity (∆ + ) were all calculated for the four different seasons (Autumn, Winter, Spring and Summer) and the two main regions (North and South) using the ‗vegan' package on the statistical software ‗R project'(R Development Core Team, 2014).

Results

Scientific survey and fishery/fisherman data analysis

The scientific survey CPUE analysis: Depth, seasonal and spatial distribution

The results related to the scientific survey data are firstly presented. A total number of 62 hauls with predetermined depths were distributed along the Lebanese coast (Figure 19). Gillnets were lowered in the majority of these hauls (Gillnets: 36 hauls; Trammel nets: 20 hauls; Long liners: 6 hauls) and nearly most hauls were lowered during the summer season. Furthermore, a large amount of hauls (52) had depths less than 200 m (versus 7 in [200-400[and 3 in [400-600] with a few having greater depths. Moreover, more hauls were performed in the southern region (26 hauls versus 19 for the central and 17 for the northern regions) (Table 12). 13).

Table 13: List of species (with their total number) caught in the CIHEAM PESCA-Libano survey with CPUE (kg/unit effort) per depth stratum, season and region (N: north; C: central; S: south) of the Lebanese coast. The gear used to catch each species is also represented (T: trammel nets; G: gillnets; L: longlines) along with the International Union for the Conservation of Nature (IUCN) Red List Category for each species caught. No gear was lowered in winter at depth strata [200-400[and [400-600] and in summer at depth stratum . The percentages are according to the general total. The spatial distribution of all survey elasmobranchs and sharks and batoids separately was presented by the map interpolation of CPUE (expressed in kilograms and number) and specific richness. Such interpolation can assign predicted values to all non-sampled locations to provide a wider picture of the distribution in this case.

Biomass distribution of all elasmobranchs combined or separated was presented by the CPUE (expressed in kilograms). The highest values were observed in the southern region of the Lebanese coast for sharks, batoids, and the combined set of elasmobranchs. However, batoids showed to have an important biomass in certain central and northern regions of the coast, but not extending to further points. Furthermore, between shark and batoid data, sharks showed to have a larger biomass in general (Figure 20a).

The distribution in number of all elasmobranchs combined or separated was presented by the CPUE (expressed in number). High values were observed as extended from the central to the southern region for the combined and batoid data sets. Moreover, high values were also observed in the north for both data sets but not extending to further non-sampled points. The shark sample, however, displayed extended high values in the south and high values in confined areas located in the northern and central regions. In addition, between shark and batoid data sets, batoids displayed larger numbers in general (Figure 20b).

The distribution of specific richness demonstrated that more species were caught in the southern and central regions, shown by the extended red region, for the combined and batoid data sets.

Sharks, however, showed a high number of species in a confined area in the central and northern regions, but not extended to further points. Finally, between shark and batoid data sets, batoids displayed a higher specific richness in general (Figure 20c).

Fishery and fishermen data analyses: Seasonal and depth variation

The results related to the fishery and fishermen data are presented in this section. A total number of 17 elasmobranchs (N=184), 8 sharks and 9 batoids, were collected from major fisheries or fishermen catches during winter, autumn, spring and summer at two depth strata ([0-300[; [300,600]). No elasmobranchs were collected from catches in spring at depth stratum [300-600]; moreover, all batoids were collected from catches at the depth stratum [0-300[. Sharks, however, displayed their presence at the two depth strata. In addition, the number of sharks collected ranged from a minimum of one for I. oxyrinchus and H. perlo to a maximum of 16 for C.

granulosus. The number of batoids collected ranged from a minimum of one for D. marmorata to a maximum of 69 for R. rhinobatos. Regarding the region of collection, the majority of shark species were collected form the northern region of the coast, followed by the southern region, and only a few were collected from the central region. On the other hand, no batoids were collected from the central region and the majority were collected from the northern region of the coast (Table 14).

Furthermore, the sharks collected from fisheries and fishermen varied seasonally and by depth.

The most prominent shark was C. granulosus. It was collected from catches in most seasons (autumn, winter, and summer) only at depths between 300 and 600 m. The least collected shark were I. oxyrinchus and H. perlo; only one individual of each was caught in spring and winter, respectively, at depths less than 300 m. Other sharks were collected during various seasons at both depth strata, except M. mustelus and S. blainville which were not observed at depths greater than 300 m (Table 14).

Regarding batoids, none was caught at depth stratum [300-600] as mentioned previously. The most prominent one was R. rhinobatos that was observed in all four seasons. The least batoid observed was and D. marmorata, of which only one individual was observed in winter at a depth less than 300 m (Table 14).

Table 14: The list of species (and number) collected from fisheries and fishermen catches with their mean total weight (W T ) and total length (L T ) per depth stratum, season and region (N: north; C: central; S: south) along the Lebanese coast. The gear used to catch each species is also represented (T: trammel nets; G: gillnets; L: longlines) along with the International Union for the Conservation of Nature (IUCN) Red List Category for each species caught. The percentages are according to the general total.

Statistical analyses of the main factors impacting the abundance index

PERMANOVA of the survey and fishery and fishermen data

Concerning survey data, results of PERMANOVA analyses are presented in Table 15. The CPUE (expressed in kilograms) for the combined data and batoids separately varied significantly following season, depth and gear with a significant double interaction between season and gear.

The CPUE (kg) for sharks separately varied significantly for season and gear only. On the other hand, the CPUE (expressed in number) varied significantly following season and depth for the combined data and sharks separately, and following depth only for batoids separately.

Concerning the fishery and fishermen data, the results of the PERMANOVA showed that the total weight varied significantly following season, region, depth and sexual maturity with double interactions between season and sexual maturity and sex and sexual maturity for the combined data and batoids separately. A triple interaction was only observed between season, sex and sexual maturity for the combined data. The total weight of sharks only varied significantly following season, region and depth with a triple interaction between season, depth and sex (Table 15).

CCA of the survey and fishery and fishermen data

Following PERMANOVA, a CCA was carried out to better visualize the relationships of the species observed with the environmental variables following CPUE (expressed in kilograms and number) for the survey data and the total weight for the fishery and fishermen data. The ordination diagrams with elasmobranch species and environmental variables are presented in

Spatial and seasonal diversity

The spatial and seasonal diversity was evaluated for the total of 25 species recorded through the course of this study. Regarding the spatial diversity, it was evaluated for two regions (north and south, having the cap of Beirut as a midpoint). More species were recorded in the southern region of the coast showing higher Shannon (H') and Simpson (1-D) indices. The latter region also showed higher evenness between species abundances (J') and higher phylogenic diversity (taxonomic distinctness ∆ + ) compared to the northern region (Table 16). In addition, the values of ∆ + , presented in Figure 22 (a), fall below the expected average value for the northern region.

Regarding seasonal diversity, the highest diversity and even distribution of species abundances were observed during the winter season following H', 1-D, and J'. However, spring showed to have the highest phylogenic diversity, followed by summer and winter, with the least phylogenic diversity in autumn (Table 16).

Discussion

The study represents the only evaluation of elasmobranch resources, distribution and diversity along the Lebanese coast, Eastern Mediterranean. This study uses two complementary data collection methods (scientific survey catches and fisheries and fishermen catches). Both data were analyzed separately to constitute the most complete image of the status of this fish class along the Lebanese coast. Almost 30% of the Mediterranean chondrichthyan species belonging to the 15 families (combining the scientific survey and fishery/fishermen data) were recorded along the Lebanese coast and used to assess the spatial and seasonal diversity.

Variation of abundance index

Scientific survey data

The use of scientific survey data allowed to comprehensively represent the seasonal and depth distributions and depict the spatial variation of this fish class. The results indicate that for all elasmobranchs, the CPUE played an important role in explaining spatial and seasonal abundances. Sharks were present in all depth strata. On the contrary, the presence of batoids was dramatically reduced with depth, except for D. oxyrinchus, which was recorded at depths between 400 and 600 m and frequently documented to be caught between 200 and 500 m [START_REF] Baino | Catch composition and abundance of Elasmobranchs based on the MEDITS program[END_REF]. Moreover, P. violacea was also present at the largest depth stratum (400-600 m); however, this presence contradicts with what has been documented about its pelagic occurrence at depths ranging from 1 to 381 m [START_REF] Mollet | Distribution of the pelagic stingray, Dasyatis violacea (Bonaparte, 1832), off California, Central America, and worldwide[END_REF][START_REF] Mundy | Checklist of the fishes of the Hawaiian Archipelago[END_REF][START_REF] Bester | Biological Profile: Pelagic stingray[END_REF]. In addition, the results also show that there is higher probability to find cartilaginous fish in shallow and intermediate depths (0-400 m) which comes in accordance with some observations in the Aegean Sea [START_REF] Damalas | Seasonal abundance of non-commercial demersal fish in the eastern Mediterranean Sea in relation to hydrographic and sediment characteristics[END_REF][START_REF] Maravelias | Habitat selection and temporal abundance fluctuations of demersal cartilaginous species in the Aegean Sea (Eastern Mediterranean)[END_REF]), but we have to be careful with these observations because less sampling was performed in higher depths (16% of the hauls were carried out in higher depths). The depth distribution of elasmobranchs can also be influenced by the age of the individuals as bigger or older individuals prefer deeper waters [START_REF] Gouraguine | Elasmobranch spatial segregation in the western Mediterranean[END_REF]. Therefore, the presence of elasmobranch species in different depths can indicate differences in the age structure of the populations examined. In this context, this information can enforce the fishing management and protection of these species in their habitats.

The seasonal variation in species CPUE can be attributed to the species seasonal migration or the influence of fishing activities in the shallower zone. Seasonal migration has been reported for several elasmobranchs, such as, R. clavata [START_REF] Hunter | Seasonal migration of thornback rays and implications for closure management[END_REF], C. maximus [START_REF] Francis | Distribution, seasonal abundance and bycatch of basking sharks (Cetorhinus maximus) in New Zealand, with observations on their winter habitat[END_REF], C. squamosus (Rodríguez-Cabello and Sánchez, 2014) and C. carcharias [START_REF] Weng | Migration and habitat of white sharks (Carcharodon carcharias) in the eastern Pacific Ocean[END_REF]. Temperature is also a significant factor in determining the distribution and abundance of some elasmobranch species [START_REF] Hopkins | The influence of environmental variables on the distribution and abundance of three elasmobranchs in Tomales Bay, California[END_REF]. Moreover, most elasmobranchs are ectothermic and changes in the environmental temperature can be rapidly transferred to the body of the fish, thus, affecting most physiological processes [START_REF] Prosser | Comparative Animal Physiology, Environmental and Metabolic Animal Physiology[END_REF]. This can lead to a variation in depth or region of presence during fluctuations of temperature. Along with seasonal migration as a reason, the significant variations in CPUE (whether in terms of biomass or density) according to season can also be attributed to environmental conditions such as the properties of the water mass as well as predator-prey relationships, daily migrations, breeding and feeding migrations, fishery [START_REF] Bianchi | Study of the demersal assemblages of the continental shelf and upper slope off Congo and Gabon, based on the trawl surveys of the RV -Dr. Fridtjof Nansen‖[END_REF][START_REF] Koslow | Community structure in North Atlantic deep-sea fishes[END_REF][START_REF] Gordon | Environmental and biological aspects of slope dwelling fishes of the North Atlantic[END_REF], or social structure of the population [START_REF] Mourier | Evidence of social communities in a spatially structured network of a free-ranging shark species[END_REF].

The largest biomass in the southern region of the Lebanese coast may be attributed to the different gear used and the species caught because bottom longlines were only lowered in the southern region and a 150 kg H. griseus was caught in a single haul there, which might have caused this abnormal biomass value. Moreover, it has been documented that bottom longlines incidentally bring several demersal species such as Mustelus sp, Squalus sp., Torpedo sp. and especially species of the Rajidae family, which represent 6 to 19 percent of the total catch [START_REF] Stergiou | Gillnet and longlines fisheries in Cyclades waters (Aegean Sea): species composition and gear competition[END_REF]. Therefore, such biomass distribution may be attributed to longlines (being lowered in the south only). The observed spatial patterns could also be attributed to the specific topographic and bathymetric conditions of the Lebanese coast. For example, the Lebanese coast is characterized by a narrow continental shelf, especially in the south, and mainly rough bottom grounds with intensive rocky patches [START_REF] Goedicke | Submarine canyons on the central continental shelf of Lebanon. The Mediterranean Sea a natural sedimentation laboratory[END_REF][START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF]. The distribution of the species richness can also be related to various abiotic and biological factors. Information on currents, temperature, salinity, nutrient concentration and the availability of food are important and should be considered in future studies. Furthermore, many causes can also be taken into account for this observed distributional pattern, such as, fishery and pollution, because the main understanding of the ecology of elasmobranchs is limited and even unknown in the region studied.

Fishery data

The data from fishery and random fishermen catches was used to complement the information related to the distribution and presence of cartilaginous fish species along the Lebanese coast.

Artisanal fishery exploitation can greatly affect the abundance and size composition of long-lived species, such as elasmobranchs [START_REF] Pinnegar | The -shifting baseline‖ phenomenon: a global perspective[END_REF]. According to [START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF], the Lebanese marine production of elasmobranchs was 60 tonnes in 2003, accounting for 2% of all groups caught. Similar to the survey data, the observed seasonal and depth distribution for the fishery/fishermen data may be influenced by biological or environmental factors. More elasmobranch species were observed in the fishery and fishermen data rather than the scientific survey data. This might be attributed to the fact that Lebanese artisanal fishermen target and specify the hauls of their catches according to personal experience, and many fishermen sell their various catches in major fisheries providing a higher probability of finding more species in fisheries rather than in a scientific survey. In addition, the survey involves a single gear at a specific georeferenced point with an increased possibility of finding no elasmobranchs. The majority of the elasmobranchs of the fishery/fishermen data, were collected from the northern region in Lebanon, particularly, a major fishery in Tripoli. The highest percentage of navigation licenses and the majority of fishing operations occur in the latter region [START_REF] Majdalani | Census of Lebanese Fishing Vessels and Fishing Facilities[END_REF]. In addition, the presence of some species in the survey data but not in the artisanal fishery/fishermen data or vice versa may indicate marked declines of these populations, differences in the spatial, depth or seasonal distributions of these species, or the depths during fishing activities, which are mostly carried out at depths less than 50 m along the Lebanese coast [START_REF] Majdalani | Census of Lebanese Fishing Vessels and Fishing Facilities[END_REF].

Rhinobatos rhinobatos was the most commonly observed elasmobranch in the fisheries of northern region of Lebanon. This elasmobranch is subject to fishing pressure in several regions especially Iskenderun Bay, northeastern Mediterranean [START_REF] Cicek | Study on the potentially economical important species trawled from Karatas¸ (Adana) Coasts[END_REF], where it is discarded dead or dying, because of poor commercial value [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF]. Some studies declared its extinct status from the northern Mediterranean and its persistent presence in areas of the southern Mediterranean, particularly the Gulf of Gabés [START_REF] Sciara | Rhinobatos rhinobatos[END_REF]. However, the results of this study confirm its presence in the eastern Mediterranean with a significant commercial value in the northern region of Lebanon. In this context, there is an urgent need to assess the status of this species, develop and implement management plans in order to facilitate the conservation and sustainable management of this and all chondrichthyan species in the region.

Factors influencing spatial and seasonal diversity

The variations in spatial and seasonal diversity may be attributed to various environmental and anthropogenic factors. Spatial diversity may vary following the topography or bathymetry of the region as well as the convergence of the currents, all of which can affect species richness and diversity due to various species affinities or ecological requirements. The nature of the bottom and the fact that the continental shelf is narrower in the south [START_REF] Goedicke | Submarine canyons on the central continental shelf of Lebanon. The Mediterranean Sea a natural sedimentation laboratory[END_REF] may also have attributed to the variation of spatial diversity between the north and the south in the study area. In addition, human activity also has an influence on spatial diversity because except for a short stretch (about 22 km) from Tyre to Ras el Naqoura in the south, most of the Lebanese coast ( 225km) is greatly influenced by anthropogenic activity [START_REF] Khater | Terrestrial biodiversity in Lebanon[END_REF]. The presence of two legal coastal nature reserves, the -Tyre Coast Nature Reserve‖ (Decree 708, 05/11/1998) in the south and the -Palm Islands Nature Reserve‖ (Decree 121, 09/03/1992) in the north may have also positively affected this diversity. Furthermore, intense fishing activities in some regions, especially in the northern region of the study area, can cause reductions observed in species richness [START_REF] Greenstreet | Fishing and the ground-fish assemblage structure in the northwestern North Sea: an analysis of long-term and spatial trends[END_REF]Rice and Gislason, 1996). For example, the longterm decline in abundance of three ray species and other species of large bodied carcharhiniform sharks in Biscay Bay was attributed to the persistent effects of bottom trawling throughout the area [START_REF] Quero | Incidence de la pêche sur la biodiversité ichtyologique marine: Le bassin d'Arcachon et le plateau continental sud Gascogne[END_REF]. Thus, further analysis of time-series changes in the distribution and abundance of elasmobranchs, their life-history characteristics and their patterns of exploitation, are indispensable to confirm the role of fishing effort in the decrease of some of these species and the alteration of their diversity.

Regarding seasonal diversity, its variation can be attributed to the change in temperature, fishing effort that varies according to season, and the depth at which fishing operations took place.

Temperature plays an important role in the seasonal migrations of several elasmobranchs species in nearshore waters [START_REF] Talent | The occurrence, seasonal distribution, and repro-ductive condition of elasmobranch fishes in Elkhorn Slough,California[END_REF][START_REF] Wallman | Effects of parturition and feed-ing on thermal preference of Atlantic stingray, Dasyatis sabina (Lesueur)[END_REF][START_REF] Wiley | The ecology of elasmobranchs occurring in the Everglades National Park, Florida:implications for conservation and management[END_REF].

Species diversity decreases with depth especially for the deep water fish fauna that are influenced by the temperature difference throughout their depth range [START_REF] White | Oceanic anoxic events and allopatric speciation in the deep sea[END_REF]. Moreover, diversity levels can also be influenced by oceanographic factors especially those related to high marine productivity. Large elasmobranches can be distributed in shallow-water according to plankton biomass, which decreases with depth and varies according to season [START_REF] Lalli | Biological Oceanography: an Introduction[END_REF][START_REF] Pough | Vertebrate Life[END_REF]. Some elasmobranchs are found in plankton-rich near surface waters, other species feed on invertebrates and fish in deep water [START_REF] Pough | Vertebrate Life[END_REF]. Furthermore, the definite prey availability in spring due to the phytoplankton bloom [START_REF] Lakkis | Composition, annual cycle and species diversity of the phytoplankton in Lebanese coastal water[END_REF]) can be a possible explanation of the highest taxonomic diversity observed during this season.

Consequently, the results of this study provide a quantitative description of spatio-temporal distribution and diversity of the cartilaginous fish community along the Lebanese coast to complete and extend the knowledge of the biological and ecological interactions of this fish class. More than 90% of elasmobranch species worldwide inhabit demersal ecosystems on continental shelves and slopes [START_REF] Compagno | Alternative life-history styles of cartilaginous fishes in time and space[END_REF], which makes them vulnerable to fishing activities. Several consequences in the marine ecosystems can result from the declines of these top predators. The information presented here is the first along the Lebanese coast and of significant value. It should be used to evaluate the conservation status of species and define the threats brought upon their populations notably by the artisanal fishing operations in Lebanon.

This study also constitutes a starting point for a continuous assessment of the impact of natural and anthropogenic factors on cartilaginous fish species along the coast of Lebanon.

Mots clés:

Liban; regression longueur-poids; poissons cartilagineux ; pêche ; elasmobranches

Introduction

Elasmobranch catches represent around 1.1% of the total landings in the Mediterranean Sea [START_REF] Serena | Field identification Guide to the sharks and rays of the Mediterranean and Black Sea[END_REF]. The maintenance of fishing pressure on elasmobranchs increases their risk of extinction [START_REF] Ferretti | Loss of large predatory sharks from the Mediterranean Sea[END_REF], especially in the eastern Mediterranean where these fish populations are declining through direct fishing pressure and bycatch (Basusta et al., 2012b).

Length-weight relationships for fish populations are important to comprehend the growth rate, age, and other factors influencing of population dynamics [START_REF] Kolher | Length-weight relationships for 13 species of sharks from the western North Atlantic[END_REF]. They help in predicting weight from length as required in yield assessment [START_REF] Garcia | Lengthweight relationships of demersal fishes from the Gulf of Salamanca, Colombia[END_REF] and calculation of biomass. Due to the absence of information on length-weight relationships of cartilaginous fish along the Lebanese coast and its scarcity in the eastern Mediterranean, the parameters for 8 elasmobranchs are reported. This study aims to create significant approaches in the population dynamics of these cartilaginous fish inhabiting the Lebanese coastal waters. The results also provide new maximum lengths and weights for these species.

Materials and Methods

Specimens were collected from December 2012 to October 2014 from the Lebanese marine waters, eastern Mediterranean. Sampling was performed through observation of major fisheries along the coast and through the CIHEAM-PESCA Libano scientific survey, in the framework of the CANA project --Establishing Monitoring and Sustainable Development of the Lebanese Sea‖ -of the Lebanese National Council for Scientific Research (CNRS-L) performed during the same time period. These samples were collected using long liners, trammel nets and gillnets through both sampling manners. After collection, the specimens were identified using the two identification guides of [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF] and [START_REF] Golani | Fishes of the eastern Mediterranean: Turkish Marine Research Foundation[END_REF]. Total lengths (L) were measured to the nearest centimeter (cm) using a measuring tape. Total weights (W) less than five kilograms were measured to the nearest gram (g) using an electronic balance, and weights greater than five kilograms were measured to the nearest 100 g using a scale. The length-weight relationship (LWR: W=aL b ) curve parameters, a and b, were estimated using a nonlinear least squares function nls in the statistical software R (R Development Core Team, 2014). The start values of these parameters were derived from the log transformation of the two variables using the linear model function lm. The coefficient of determination (r 2 ) aids in determining the accuracy of the model prediction skills. Finally, statistical comparison of WLR between sexes was performed by applying an ANCOVA test. When significant differences were observed, WLR was estimated for each sex; when no significant differences were observed, one WLR was estimated for the sexes combined.

Results and Discussion

A total of 235 elasmobranch individuals comprising of 3 shark species and 5 batoid species were collected in this study. The length and weight characteristics, as well as, the sample size and parameters of the length-weight relationships are represented in Table 17. The sample sizes ranged from a minimum of 11 for S. blainvillei to a maximum of 70 for R. rhinobatos.

Significant differences were only observed between the males and females of C. granulosus and T. marmorata (ANCOVA; P<0.05). The value of parameter b ranged from a minimum of 1.752

for the females of T. marmorata to a maximum of 3.337 for the combined sample of R.

miraletus. All estimated relationships showed negative allometry except those for R. rhinobatos, R. clavata and R. miraletus that showed positive allometry with b values of 3.102, 3.203, and 3.337 respectively. The most accurate model was shown to be that of R. rhinobatos (r 2 =0.9873) and the least accurate was that of the females of C. granulosus (r 2 =0.6380). This variation in model accuracy can be due to the absence of a complete sample consisting of different size classes. Furthermore, some samples in this study do not consist of small individuals for some species, such as, females of C. granulosus. Hence, the relationships presented should only be applied to the observed length ranges [START_REF] Petrakis | Weight length relationships for 33 fish species in Greek waters[END_REF][START_REF] Gonçalves | Weightlength relationships for selected fish species of the small-scale demersal fisheries of the south and south-west coast of Portugal[END_REF]. Information related to the length-weight relationships of elasmobranchs are absent along the Lebanese coast, however, showing an important presence in the eastern Mediterranean especially in the Aegean Sea [START_REF] Filiz | A preliminary study on length-weight relationships for seven elasmobranch species from North Aegean Sea, Turkey[END_REF][START_REF] Filiz | Length-weight relationships of 24 fish species from the North Aegean Sea, Turkey[END_REF]Ismen et al., 2007a;[START_REF] Ozaydın | Length-weight relationships of fishes captured from Izmir Bay, Central Aegean Sea[END_REF][START_REF] Cakir | Length-weight relationships of 24 fish species from Edremit Bay, Aegean Sea[END_REF][START_REF] Ilkyaz | Length-weight relationship of 62 fish species from the Central Aegean Sea, Turkey[END_REF][START_REF] Ismen | Length-weight relationships for ten shark species from Saros Bay (North Aegean Sea)[END_REF]Yigin and Ismen, 2009a;[START_REF] Bilge | Weight-length relations for 103 fish species from the Southern Aegean Sea, Turkey[END_REF][START_REF] Yapici | First length-weight relationships of 11 fish species in the Aegean Sea[END_REF], Iskenderun Bay (Basusta et al., 2012a) and Antalya Bay [START_REF] Guven | Length-weight relationships of sharks in Antalya Bay, eastern Mediterranean[END_REF]. This information helps in deriving the weight estimates of these elasmobranchs from their lengths at sea in order to limit the catches of these fish along the Lebanese coast. This might be a good tool to induce laws to limit the overexploitation of these fishes through direct fishing and bycatch by establishing a minimum catch weight limit and taking into consideration these weights when the lengths are estimated at sea.

Biologie des populations d'une espèce en voie

Introduction

Paleoecological, archaeological, and historical data show that consequent alterations in ecological communities occurred decades to centuries after the start of anthropogenic overfishing [START_REF] Jackson | Historical overfishing and the recent collapse of coastal ecosystems[END_REF]. More human impact is observed in the Mediterranean Sea than in any other sea [START_REF] Blondel | Biology and wildlife of the Mediterranean region[END_REF]. Natural and anthropogenic events that have shaped its biodiversity in the past will continue to do so in the future [START_REF] Coll | The Biodiversity of the Mediterranean Sea: Estimates, Patterns, and Threats[END_REF]. In the Mediterranean, cartilaginous fish are characterized by their diversity with a total estimate of 80 species (45 sharks, 34 batoids, and one chimaera) found in its waters [START_REF] Compagno | Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes[END_REF][START_REF] Compagno | A Field Guide to the Sharks of the World[END_REF][START_REF] Serena | Field identification Guide to the sharks and rays of the Mediterranean and Black Sea[END_REF]. These fishes are an important bycatch of commercial fisheries targeting bony fishes [START_REF] Bradai | Elasmobranchs of the Mediterranean and Black sea: status, ecology and biology. A Bibliographic Analysis[END_REF]. Moreover, it has been shown that sharks in the Mediterranean Sea, such as, the hammerhead (Sphyrna spp.), blue (Prionace glauca), mackerel (Isurus oxyrinchus and Lamna nasus), and thresher sharks (Alopias vulpinus), have declined by more than 97% in number and -catch weight‖ over the last two centuries and are in a risk of extinction if current fishing pressure continues [START_REF] Ferretti | Loss of large predatory sharks from the Mediterranean Sea[END_REF]. In addition, the Mediterranean Sea is considered one of the seven Chondrichthyan biodiversity hotspots and one of the three main hotspots where the biodiversity of sharks and rays was seriously threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. Among the 80 species of cartilaginous fish known in the Mediterranean, 71

were assessed in the frame of the International Union for Conservation of Nature (IUCN) red list, and more than 40% (34 species) are threatened and face an elevated risk of extinction [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF].

The Common Guitarfish Rhinobatos rhinobatos L. 1758 is an elasmobranch of the Rhinobatidae family that is classified as Endangered by the IUCN [START_REF] Sciara | Rhinobatos rhinobatos[END_REF]. It is an ovoviviparous species with a nine months gestation period and an average number of eight to 14 embryos per pregnancy [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF]. This increases the concern of its Endangered status as most elasmobranchs have a slow growth rate, late maturity and low fecundity compared to bony fish;

this results in low reproductive potential and low capacity for population increase [START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF]. Furthermore, [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF] linked depth and body size to extinction risk, where larger species occupying shallow waters are at a greater risk and the majority of the threatened families are rays.

It is a demersal species found in the Eastern Atlantic and the Mediterranean [START_REF] Bauchot | II Vertébrés[END_REF]. Its presence in the latter region is more prevalent in the southern and eastern regions [START_REF] Whitehead | Fishes of the North-eastern Atlantic and the Mediterranean[END_REF][START_REF] Capapé | Les Sélaciens des côtes méditerranéennes: Aspects généraux de leur écologie et exemples de peuplements[END_REF], especially around the Gulf of Gabès, on the eastern coast of Tunisia [START_REF] Quignard | Liste commentée des sélaciens de Tunisie[END_REF]. The Common Guitarfish species was documented to be extinct in the northern regions of the Mediterranean [START_REF] Relini | Stato attuale dei censimenti ittici nei mari Italiani. Atti II Seminario Italiano Censimenti Faunistici dei Vertebrati[END_REF][START_REF] Baino | Catch composition and abundance of Elasmobranchs based on the MEDITS program[END_REF].

In the eastern Mediterranean, the study area, the Common Guitarfish is commonly found in Turkish waters and discarded dead or dying because of poor commercial value [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF]. Nonetheless, it is commonly found in Lebanese fisheries presenting a significant commercial value, where its meat is consumed as fish filets with a value ranging from four to six US dollars per one kilogram. It is targeted by Lebanese fishermen using longlines and sometimes caught as bycatch with entangling nets, provided that the Lebanese fleet is artisanal and the number of licensed vessels in 2011 was 1460 [START_REF] Pinello | Fishing fleet data for 2011[END_REF]. The lack of management measures (particularly specific to elasmobranchs) and commercial fishing has created the need to manage the stocks of such elasmobranch species in this region.

Basic biological information needed for stock assessment is lacking for many of these eastern Mediterranean cartilaginous species, including minimum, maximum, and average sizes, as well as length-to-weight relationships. However, these data are essential to understand the growth rate, age structure, and other aspects of population dynamics. Size conversions also have a practical value in fisheries. One measure currently in practice is the establishment of minimum size limits and usually a minimum weight. Since sizes must be estimated at sea, means for converting lengths to weights are essential to fishermen.

Rare are the studies performed on the Common Guitarfish in the eastern Mediterranean, and none in the Lebanese coastal waters. Most studies, dealing with biological and aging aspects, were performed in the Egyptian Alexandria waters (southeastern Mediterranean) [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF], the Turkish Iskenderun Bay (northeastern Mediterranean) [START_REF] Basusta | Diet of Common Guitarfish (Rhinobatos rhinobatos L., 1758) in the Iskenderun Bay (Northeastern Mediterranean)[END_REF][START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF][START_REF] Basusta | Age and growth of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (northeastern Mediterranean,Turkey)[END_REF][START_REF] Cek | Biological observations on the common guitarfish (Rhinobatos rhinobatos Linnaeus 1758) from Iskenderun Bay[END_REF][START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF], and the Tunisian coasts (south-central Mediterranean) [START_REF] Capapé | Premières données sur le cycle de reproduction de Rhinobatos rhinobatos (Linne, 1758) et de Rhinobatos cemiculus Geoffroy Saint-Hailaire 1817 des côtes tunisiennes[END_REF][START_REF] Capapé | Etude du régime alimentaire de deux Sélacienscommuns dans le golfe de Gabès (Tunisie): Rhinobatos rhinobatos (Linne, 1758) et Rhinobatos cemiculus (Geoffroy Saint-Hailaire 1817)[END_REF][START_REF] Capapé | Aspects de la biologie de la reproduction de Rhinobatos rhinobatos (Rhinobatidae) des eaux tunisiennes[END_REF].

This study, being the first for the Lebanese coastal waters, essentially reflects the biological aspects of the Common Guitarfish population. In response to the immediate needs for management initiatives, it aims to contribute to a better knowledge of the growth, sexual maturity, reproduction and nutritional strategy of the Common Guitarfish population in the Lebanese marine waters. Length and weight data, sex ratio, length-weight relationships, length at which 50% of the individuals matured, gonadosomatic and hepatosomatic indices, condition factor as well as the main prey items found in the stomachs of this species are presented and compared to available data from other areas. This study provides a first evaluation of the population health condition and aims, at a longer term, to stimulate the implementation of regulations to control the fishing of this endangered cartilaginous species.

Materials and Methods

Sampling and study area

A total of 67 specimens of Common Guitarfish were collected by bottom long liners through four different ports along the Lebanese coastal waters located in the Levantine basin, eastern Mediterranean, at depths ranging from 10 to 110 m between December 2012 and January 2014.

These were collected through observation of catches of the fisheries along the Lebanese coast, with the majority collected in the Tripoli port (Figure 23). The exact position of the fishery catches is not available because the majority of Lebanese fishermen have no Global Positioning System (GPS) instruments; however, the depth is provided.

The specimens were identified according to the two field identification guides of [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF] and [START_REF] Golani | Fishes of the eastern Mediterranean: Turkish Marine Research Foundation[END_REF]. They were either dissected on the site of collection, whether on a port or in a fishery, or preserved in ice and later frozen at -20°C to be eventually treated in the laboratories of the Lebanese National Council for Scientific Research-National Center for Marine Sciences in Batroun.

Figure 23: Location of the major ports along the Lebanese coast.

Biological measures

Upon treatment, the specimens were observed for external damages and males were macroscopically sexed by examining the claspers. The external length of the clasper (L C ) in males was measured from the tip of the clasper to the base of the pelvic fin all using a calliper to the nearest millimetre (mm). In the rest of the paper, all lengths and weights (less than five kilograms) were measured to the nearest centimetre (cm) and nearest gram (g), respectively, using an electronic balance and a measuring tape. Weights greater than five kilograms were measured using a scale to the nearest 100 g.

Morphometric measurements were performed for each Common Guitarfish specimen. The total weight (W T ) and total length (L T ) were measured prior to dissection. The liver and gonads were removed along with the expanded uteri in the case of a gravid female.

The weight of the liver (W L ) was measured and used for the computation of the hepato-somatic index (I H ) [START_REF] Bulow | Comparisons of two bluegill Populations by Means of the RNA-DNA ratio and Liver-Somatic Index[END_REF][START_REF] Adams | Estimation of largemouth bass, Micropterus salmoides Lacépède, growth using the liver somatic index and physiological variables[END_REF] where:

I H = W L × W T -1 × 100
The I H gives useful indication of energy reserves because the liver is an important energy storage in fish [START_REF] Halton | Practical Exercises in Parasitology[END_REF].

The weight of the gonads (W G ) including the weight of the testes in males, and oviductal glands, accessory glands, ovary and oviducts in females [START_REF] Gristina | Biological information on Target Species: Sex-determination, Maturation stages and Gravimetric indexes[END_REF] were also measured for the computation of the gonado-somatic index (I G ) [START_REF] Bougis | Recherche biométriques sur les rougets (M. barbatus L., M. surmuletus L.)[END_REF] where:

I G = W G × W T -1 × 100
The I G allows to investigate the changes in gonad weight in relation to the weight of fish.

Sexual maturity was determined using the Instruction Manual for the MEDITS Survey -Version 6 (MEDITS, 2012), where the ovoviviparous elasmobranch females were classified among eight maturity stages (1: Immature; 2: Developing; 3a: Capable to reproduce; 3b: Early pregnancy; 3c:

Mid pregnancy; 3d: Late pregnancy; 4a: Regressing; 4b: Regenerating), and the males among five maturity stages (1: Immature; 2: Developing; 3a: Spawning capable; 3b: Actively spawning; 4: Regressing).

Finally, the condition factor (K) [START_REF] Fulton | The rate of growth of fishes[END_REF] was also computed using total weight (W T ) and total length (L T ), where:

K = W T × L T -3 × 100
The K is used for comparing the ‗condition', ‗fatness', or 'well-being' of fish, based on the assumption that heavier fish of a given length are in better condition [START_REF] Froese | Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations[END_REF].

Stomach content analysis

The total weight of the stomach (W S ) was measured. Stomachs with food contents were preserved in 4% formaldehyde until identification. The stomach contents were then rinsed under tap water. Their weight was measured if possible to the nearest gram, counted and identified to the lowest possible taxon [START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF].

According to [START_REF] Hyslop | Stomach contents analysis--a review of methods and their application[END_REF], two indices were calculated. The coefficient of vacuity (C V ) was calculated to reflect the richness or lack of food in the environment:

C V = E V × N -1 × 100
where E V is the number of empty stomachs and N is the total number of stomachs examined.

The percentage of fullness (F I ) was also calculated for each stomach:

F I = W P × W S -1 × 100
where W P is the weight of the prey items in each stomach.

Stomach fullness was classed based on a five-point scale estimated by the percentage of fullness: empty, partially empty (1-25%), slightly full (26-50%), partially full (51-75%), and full (76-100%).

Moreover, three indices were used to show the significance of different prey items. The frequency of occurrence (O % ), the coefficient of prey numerical abundance (N % ), and the percentage of weight (W % ) [START_REF] Hynes | The food of freshwater sticklebacks (Gasterosteus aculeatus and Pygosteus pungitius) with a review of methods used in studies of the food of fishes[END_REF][START_REF] Hyslop | Stomach contents analysis--a review of methods and their application[END_REF][START_REF] Bowen | Quantitative description of the diet[END_REF]:

O % = N P × M -1 × 100 N % = n × n P -1 × 100 W % = m × m P -1 × 100
where N P is the number of stomachs containing a specific prey group, M is the number of stomachs with prey remains, n is the number of prey of each taxonomic group, n P is the total number of prey items, m is the mass of prey of each taxonomic group, and m P is the total mass of prey items.

Out of these indices, the importance of each food item in the diet was obtained by the Index of Relative Importance (I RI ) [START_REF] Pinkas | Food habits of albacore, bluefin tuna, and bonito in Californian waters[END_REF]) that was modified by [START_REF] Hacunda | Trophic relationships among demersal fishes in a coastal area of the Gulf of Maine[END_REF]:

I RI = O % × (N % + W % )
Finally, the percent of IRI (I %RI ) for each prey type was estimated in order to make comparisons easier among food types [START_REF] Cortés | A critical review of methods of studying fish feeding based on analysis of stomach contents: application to elasmobranch fishes[END_REF].

Regressions and statistical analyses

All regressions and statistical analyses were performed using the statistical software ‗R project' (R Development Core Team, 2014). A linear regression model was used to examine the relationship between total length and clasper length (L C =a + bL T ) using the lm function. The coefficient of determination (R 2 ) was used to evaluate the quality of the model.

The total length and total weight were used to produce the length-weight relationship in a nonlinear power regression (W T =aL T b ) [START_REF] Lecren | The Length-Weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis)[END_REF] where ‗a' and ‗b' are the parameters to estimate using the nls function. A nonlinear power regression was also used to produce the relationship between the gonad weight and total length of male specimens (W G =aL T b ). Nonlinear regressions were used to represent any regression of weight on length because any weights will scale to the cubic power of length [START_REF] Froese | Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations[END_REF]. In addition, the length at which 50% of the fish are mature (L 50 ) was estimated for all length classes using a logistic curve from a generalized linear model (GLM) with logit link using the glm function. Furthermore, statistical comparison of weight-length relationships between sexes was performed by applying an ANCOVA test using the anova function. A Shapiro-Wilk normality test was used to test for the normality of the sample using the shapiro.test function, and the Wilcoxon rank sum test was used to test for differences in lengths, weights and percentages of fullness between males and females using the wilcox.test function. Moreover, a Kruskal-Wallis rank sum test was used to examine the differences between total length and total weight according to sexual maturity and between the biological indices (I G , I H and K) according to season using the kruskal.test function. The sex ratio was calculated for the whole sample and compared to the 1:1 proportion by a chi-squared test [START_REF] Zar | Biostatistical analysis[END_REF] using the chisq.test function.

Moreover, in order to determine the feeding strategy of both species, feeding strategy graphs were plotted following the Costello (1990) method. The feeding strategy graphs particularly illustrate the dominance and the rarity of each group of prey in both seasons and the specialized or generalized feeding strategy.

Results

Sex ratio and length frequency distribution

A total of 67 (33 females and 34 males) of Common Guitarfish were reported to be collected at depths ranging from 15 to 110 m, with 91% (61 individuals) of the specimens collected at depths less than 50 m. The sex ratio of males to females was found to be 1.03. No significant differences between the number of males and females were observed and the sex ratio was not significantly different from 1:1 (χ 2 test, χ 2 = 0.0149, d.f. = 1, P>0.05). The length and weight measurements for each sex are represented in Table 18. The length-frequency distribution for each and both sexes shows that 56.7% ( 38

Length-weight relationship

The weight (W T )length (L T ) relationship was estimated using a nonlinear power regression analysis (Males: W T = 0.0012 L T 3.241 , R 2 = 0.98, n = 34; Females: W T = 0.0023 L T 3.089 , R 2 = 0.99, n = 33). No significant differences were obtained from the statistical comparison of weightlength relationships between males and females (ANCOVA, F = 0.2381, P>0.05); therefore, the sexes were combined. The calculated parameters of W T -L T relationship for sexes combined demonstrated a scaling coefficient greater than three (b=3.096) with a determination coefficient equal to 0.99 (Figure 25). Examination of the male and female maturity stages according to length classes in a logistic regression indicated that the length at 50% maturity (L 50 ) was 78.57 ± 4.88 cm for males and 84.73 ± 5.81 cm for females (Figure 27). The weight of the gonads along with clasper length was the indicator of maturity in males. An increase in clasper length (Figure 28a) with respect to total length was observed in males following a linear regression (L C =0.2304L T -8.375). Moreover, the nonlinear relationship between gonad weight and total length (Figure 28b) is given by the following equation 2.489 . No relationship was found between the gonad weight of the females and the total length. The only late pregnant female of L T = 92.5 cm was caught in December 2013 bearing six embryos of W T ranging from 51 to 55.8 g (mean W T = 53.3 g) and L T ranging from 23 to 24 cm (mean L T = 23.6 cm). Thus, parturition would have taken place at a later date. 2.489 ) and the total length of the individual Common Guitarfish, respectively.

W G = 0.00017 L T
The I H values of the Common Guitarfish specimens peaked in summer (Figure 29a) and the I G peaked in autumn (Figure 29b). The I H values fluctuated throughout the year with a relative decrease in winter and autumn when the I G increased (Figure 29a,b). The condition factor (K)

showed almost constant values in all seasons and the highest value in autumn with the increase in I G (Figure 29c). Finally, there were significant differences between the I H according to seasons

Stomach content analysis

A total of 67 stomachs were examined out of which 56 stomachs were found to be proper for analysis, and 34 (16 males and 18 females) of the 56 stomachs were found to contain identifiable food items. The coefficient of vacuity was estimated to be 39.29% for all the specimens, 44.83%, and 33.33% for male and female specimens respectively. The majority of the full stomachs (61.76%) belonged to individuals having a length less than 80 cm applying to both males (41.38%) and females (33.33%) (Figure 30a,b).

Figure 30: The number of full ( ) and empty ( ) Common Guitarfish stomachs according to total length for males (a) and females (b).

Out of the 34 stomachs examined, 20 were partially empty (1-25%) and 14 were slightly full (26-50%) according to the five-point scale estimated by the percentage of fullness. The percentage of fullness (F I ) ranged between a minimum value of 6.36% for a 73 cm male and a maximum value of 47.27% for a 72 cm male (Figure 31a). The largest female with a full stomach (L T = 143 cm) had a F I = 27.16% (Figure 31b). No significant differences were observed between the F I of males and females (Wilcoxon test, W = 153, P>0.05). The Common Guitarfish was found to prey upon six categories of prey constituted of crustaceans (Penaeidae, Brachyura, Squilladae, and Juvenile Nephropidae), fish (Teleostei) and cephalopods (Octopodidae) in the autumn and winter seasons. Overall, crustaceans were the most abundant prey in the stomachs of the specimens in the autumn (93.46%) and winter (78.23%) seasons.

Moreover, the most abundant prey group in both seasons was the Penaeidae group with I %RI of 44.2 and 57.01% in the autumn and winter seasons respectively. Juveniles of the Nephropidae family constituted the secondary prey (I %RI =32.89%) in the autumn season, however, showed to be absent in the winter season, during which the Teleostei group represented the secondary prey with I %RI =21.77%. No items of the Octopodidae family were observed in the winter season after constituting the third prey item (I %RI =4.06%) in autumn. Brachyurans were considerably found in the stomachs of the specimens in winter (I %RI =20.57%) but not in autumn (I %RI =2.88%). This observation was contradicted by the Squilladae family which had an important presence in the stomachs of the specimens in autumn with I %RI =13.49%, however, showing the least importance in winter (I %RI =0.75%) (Table 19). Analysis of feeding strategy according to the Costello graphs showed that the Common Guitarfish specimens had a mixed feeding strategy. Shrimps of the Penaeidae family showed to be the most important prey group in the autumn (Figure 32a) and winter seasons (Figure 32b) having the highest O % and N % values. Juveniles of the Nephropidae family showed to be the secondary important prey group only in autumn (Figure 32a). The least important prey group in both seasons was the Octopodidae family with the lowest O % and N % values in autumn and null ones in winter. The Teleostei and Brachyura families showed high rarity in autumn but a relatively higher importance in winter, in contrast to the Squilladae family which showed an opposing trend (Figure 32a,b).

Discussion

The majority of the specimens in this study were caught over sandy and muddy bottoms at depths ranging from 15 to 50 m with few individuals at depths greater than 50 and 100 m. These and also correlate with [START_REF] Whitehead | Fishes of the North-eastern Atlantic and the Mediterranean[END_REF] and [START_REF] Buen | Fauna ictiológica : catálogo de los peces ibéricos, de la planicie continental, aguas dulces, pelágicos y de los abismos próximos[END_REF] who documented the findings of Common Guitarfish over sandy, muddy, shell and occasionally macro-algal substrates.

In addition, the depth distribution of the Common Guitarfish specimens in the Lebanese waters also correlates with the depth range recorded in Moroccan waters [START_REF] Sciara | Rhinobatos rhinobatos[END_REF] where Common Guitarfish were recorded at depths ranging from 17 to 80 m. The lack of a significant bias in the sex ratio of the examined specimens suggests that there is no sexual segregation by area or depth and/or that there is no sexual selection by the fishing gear. However, the Common Guitarfish may be segregated by sex, since [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF] showed a sex ratio of 57% males and 43% females in Iskenderun Bay, and [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF] a sex ratio on the same species of 54% females and 46% males in the Alexandria waters. We observe this kind of segregation in other marine species as Merluccius merluccius [START_REF] Piñeiro | Age estimation, growth and maturity of the European hake (Merluccius merluccius (Linnaeus, 1758)) from Iberian Atlantic waters[END_REF].

Gregarious species better exploit resources when living in groups because it is easy to find and catch prey. However, in case of limited resources, it can become a problem of intra-specific competition. The status of an individual in a population sometimes induces a spatial and/or temporal segregation between size and sex. Therefore, due to the probable availability of resources for the Common Guitarfish in our sample, no segregation between sexes was observed.

The maximum total length in this study (143 cm) corresponds to that observed in Iskenderun Bay [START_REF] Basusta | Diet of Common Guitarfish (Rhinobatos rhinobatos L., 1758) in the Iskenderun Bay (Northeastern Mediterranean)[END_REF][START_REF] Basusta | Age and growth of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (northeastern Mediterranean,Turkey)[END_REF] belonging to female specimens; however, smaller male and female specimens were observed in that region. In addition, a larger L T of Common Guitarfish was observed in this study than that observed in Tunisian waters (McEachran and Capapé, 1984b;[START_REF] Bauchot | II Vertébrés[END_REF] where the L T was noted to reach 100 cm, rarely larger, and usually 80 cm; nevertheless, this was contradicted by larger specimens in the Gabès Gulf [START_REF] Capapé | Observations biologiques comparées entre quelques espèces de sélaciens des côtes tunisiennes (Mediterranee centrale) et de la région de dakarouakam (Sénégal, Atlantique oriental tropical)[END_REF] where the maximum reported sizes were larger with 140 cm L T for males and 162 cm L T for females. [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF] also noted the largest female and male specimens of Common Guitarfish in the Alexandria waters in Egypt with a L T of 181 cm and 172 cm respectively. Taking into consideration the means of total weight and total length in both male and female specimens, the females showed to be both longer and heavier than the males;

this observation was noted by [START_REF] Casey | Age and Growth of the Sandbar Shark (Carcharhinus plumbeus) from the Western North Atlantic[END_REF], [START_REF] Ismen | Age, growth, reproduction and food of common stingray (Dasyatis pastinaca L., 1758) in İskenderun Bay, the eastern Mediterranean[END_REF], [START_REF] Skomal | Age and growth of the blue shark (Prionace glauca) in the North Atlantic Ocean[END_REF] and [START_REF] Yamaguchi | Occurrence, Growth and Food of Longheaded Eagle Ray, Aetobatus flagellum, in Ariake Sound, Kyushu, Japan[END_REF], supporting that female elasmobranchs grow longer than males.

The length-weight relationship obtained in this study correlates with the findings in Iskenderun Bay [START_REF] Basusta | Age and growth of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (northeastern Mediterranean,Turkey)[END_REF]Basusta et al., 2012a) where the weight of the individual specimens

showed to grow at a faster rate than its length. Nevertheless, these results contradict with those observed by [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF] in the same region where males displayed almost isometric growth (b=2.98) and females displayed negative allometric growth (b=2.89). The reason of this difference may be attributed to sample sizes, different habitat and physiological status.

This variation in size and growth can be due to overfishing in the region. Indeed, one of the effects of overfishing is the elimination of the largest and oldest individuals from a population or stock and the stimulation of early maturation. [START_REF] Law | Fishing in evolutionary waters[END_REF] confirmed that by stating that a large change in mortality imposed by fishing generated a big selection pressure for early maturation irrespective of any change in size-at-age. For instance, such a pattern was observed with the Northeast Arctic cod that underwent early induced maturation due to overfishing [START_REF] Lee | The effects of overfishing on marine biodiversity[END_REF].

Throughout the year, specimens with various maturity stages were observed in the Lebanese waters suggesting that the Common Guitarfish presents a partially defined seasonal reproduction according to the reproduction strategies found by [START_REF] Wourms | Reproduction and gestation in chondrichthyan fishes[END_REF] and [START_REF] Hamlett | Female reproductive system[END_REF].

A similar pattern was observed by [START_REF] Cek | Biological observations on the common guitarfish (Rhinobatos rhinobatos Linnaeus 1758) from Iskenderun Bay[END_REF] in Iskenderun Bay. Moreover, female viviparous elasmobranchs display larger sizes at maturity than males [START_REF] Capapé | Biological observations on the black torpedo, Torpedo nobiliana Bonaparte 1835(Chondrichthyes: Torpedinidae), from two Mediterranean areas[END_REF][START_REF] Consalvo | Comparative study on the reproductive biology of Torpedo torpedo (Linnaeus, 1758) and T. marmorata (Risso, 1810) in the central Mediterranean Sea[END_REF][START_REF] Pereyra | Spatial and temporal variation of length and sex composition of the narrow nose smooth-hound Mustelus schmitti Springer, 1939 in the trawl fishery off the oceanic coast of Uruguay during 2004[END_REF][START_REF] Pérez-Jiménez | Reproductive biology of the brown smoothhound shark Mustelus henlei, in the northern Gulf of California, México[END_REF][START_REF] Blanco-Parra | Reproductive biology of the banded guitarfish, Zapteryx exasperata, from the Gulf of California, México[END_REF]. This was supported in this study where significant differences were observed between male and female sizes according to sexual maturity and mature females were found to be both larger and heavier than males.

Concerning the estimation of L 50 , values were found to vary among different regions in the Mediterranean Sea. In the Tunisian coasts (south central Mediterranean), male and female Common Guitarfish were found to mature at 75 cm and 85 cm respectively [START_REF] Capapé | Etude du régime alimentaire de deux Sélacienscommuns dans le golfe de Gabès (Tunisie): Rhinobatos rhinobatos (Linne, 1758) et Rhinobatos cemiculus (Geoffroy Saint-Hailaire 1817)[END_REF][START_REF] Capapé | Aspects de la biologie de la reproduction de Rhinobatos rhinobatos (Rhinobatidae) des eaux tunisiennes[END_REF], whereas in Iskenderun Bay (northeastern Mediterranean) the L 50 was 70 cm for males and 80 cm for females in the study of [START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF] and 60 cm for males and 69 cm for females in that of [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF]. In addition, in the Egyptian Alexandria waters (southeastern Mediterranean), the lengths at which 50% of the individuals were mature were 70 cm and 87 cm for males and females respectively [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF]. In this study, L 50 was estimated to be around 85 cm for females and 78 cm for males which falls in the range of what was observed in the Tunisian coasts for both males and females and in the Egyptian Alexandria coasts for females only. This variation seems to be attributed to the lack of a wide ranged sample consisting of individuals in all size classes or to the difference in values may also be due to the different conditions in every region influencing the physiological characteristics of the population in that region, which can consequently affect its growth and development.

Parturition in the Lebanese waters might have occurred later than December as a single gravid female was caught during the latter month bearing fully formed embryos whose average W T and L T were in agreement to those observed at the end of parturition by [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF]. The above results do not correlate with those observed in Iskenderun Bay, where the I G values peaked in May for females and in November for males indicating that spawning occurred in spring [START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF]. Furthermore, differences were also observed in the Egyptian Alexandria waters, where mating was found to occur during summer and parturition later in August [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF]. The variations in reproduction of Common Guitarfish may be attributed to the conditions in the study area, the speed of development, and the knowledge that both sexes seem to be reproductively active at different times of the year, as clearly documented by [START_REF] Cek | Biological observations on the common guitarfish (Rhinobatos rhinobatos Linnaeus 1758) from Iskenderun Bay[END_REF].

The storage of nutrients in the liver has been reported for several elasmobranch species (e.g. [START_REF] Springer | Sharks in question -The Smithsonian Answer Book[END_REF]). An elevation in I H prior to reproduction is therefore common, since the nutrients in the liver might be utilized during maturation of the ovary. A decline in I H was observed along with the I G increase indicating that Common Guitarfish undergo significant reserve metabolism to acquire energy for reproductive development as clearly documented in Iskenderun Bay [START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF]. Moreover, this seasonal variation in I H agrees with what was observed in other ovoviviparous cartilaginous fish species [START_REF] Maruska | Periodic gonadal activity and protracted mating in elasmobranch fishes[END_REF][START_REF] Demirhan | Seasonality of reproduction and embryonic growth of spiny dogfish (Squalus acanthias L., 1758) in the eastern Black Sea[END_REF]. The constant condition factor throughout the study period was indicative of an evident wellness among the Common Guitarfish population and could indicate a lack of any physiological or environmental factor affecting the stock.

Analysis of the stomach contents showed more or less considerable food availability in the Lebanese waters; this was supported by a low coefficient of vacuity considering all specimens and the fact that shallow waters in the region are known to be oligotrophic [START_REF] Abi Saab | A study of the annual cycle of phytoplanctonic Population in the Palm Island Nature Reserve, Lebanon[END_REF][START_REF] Ignatiades | Scaling the trophic status of the Aegean Sea, eastern Mediterranean[END_REF]. The diet of the Common Guitarfish mainly consisted of benthic invertebrates and fishes with preference for shrimps of the Penaeidae family. These results are in agreement with what was observed by [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF][START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF]), and Bauchot et al. (1987). Juveniles of the Nephropidae family presented the secondary prey only in autumn, and the Teleostei and Brachyuran families showed an increase in importance in winter. This seasonal shift in diet seems to be attributed to the availability of each prey item in the study area.

Finally, this study draws attention to the Common Guitarfish population in Lebanon, as rare are the studies that are performed about this species in the Levantine basin. This species is majorly exploited by the longline fishery for its commercial significance due to its low cost especially in the Northern areas of Lebanon; thus, management measures should be implemented to prevent this vast exploitation of this elasmobranch group. Laws should be applied to limit the uncontrollable fishing of this elasmobranch. The data presented here will be useful for the ongoing assessment of populations, fishery stock assessments, ecological risk assessments, and species extinction risk assessments.

Population biology of the Gulper Shark

Introduction

The Mediterranean Sea is considered as one of the seven Chondrichthyan biodiversity hotspots and one of the three main hotspots where the biodiversity of sharks and rays was seriously threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF]. Among the 80 species of cartilaginous fish known in the Mediterranean (45 sharks, 34 batoids, and one chimaera), 71 were assessed in the frame of the International Union for Conservation of Nature (IUCN) red list and more than 40% (34 species) are threatened and face an elevated risk of extinction [START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF]. The main causes of these threats are linked to anthropogenic pressures which degrade marine ecosystems such as habitat degradation, pollution, littoral construction, tourism and overexploitation [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. This last factor particularly impacts the elasmobranch populations and fishing activity exerted on these populations is responsible for the reduction of their abundance [START_REF] Dulvy | Fishery stability, local extinctions, and shifts in community structure in skates[END_REF]. This decline in Mediterranean countries is a notable consequence of increased fishing effort in terms of engine power and increased capacity of fishing equipment for both artisanal and industrial fisheries. Elasmobranchs can be caught by various fishing methods although bottom trawling is considered responsible for a large amount of their bycatches and discards throughout the world [START_REF] Bonfil | Trends and patterns in world and Asian elasmobranch fisheries[END_REF].

The Gulper Shark, Centrophorus granulosus (Bloch and Schneider 1801) is an elasmobranch of the Centrophoridae family and is classified as Vulnerable by the Red List of the International Union for the Conservation of Nature [START_REF] Guallart | Centrophorus granulosus. In The IUCN Red List of Threatened Species[END_REF] on the basis of quite an important rate of decline in populations mainly due to overexploitation. It is an ovoviviparous species with the lowest described fecundity and a pregnancy with one embryo lasting for about 2 years [START_REF] Ranzi | Le base fisio-morphologiche dello sviluppo embrionale dei Selaci. Parte I (The physiomorphological basis of the embryonic development in Selachii. Part I)[END_REF][START_REF] Tortonese | Leptocardia, Ciclostomata, Selachii, Fauna d'Italia[END_REF][START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Guallart | Contribución al conocimiento de la biología y la taxonomía del tiburón batial Centrophorus granulosus[END_REF]. This increases the concern of its Vulnerable status as most elasmobranchs have a slow growth rate, late maturity and low fecundity compared to bony fish. This concern led to a low reproductive potential and low capacity for population increase [START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF].

This species is mainly distributed in eastern, western and central Atlantic, Indian Ocean, western Pacific and Western Australia [START_REF] Compagno | Part 1 -Hexanchiformes to Lamniformes[END_REF][START_REF] Last | Sharks and rays of Australia[END_REF][START_REF] Compagno | Squalidae. Dogfish sharks[END_REF].It is also not recorded in the eastern Pacific [START_REF] White | Revision of the genus Centrophorus (Squaliformes: Centrophoridae): Part 1 -Redescription of Centrophorus granulosus (Bloch & Schneider), a senior synonym of C. acus Garman and C. niaukang Teng[END_REF]. In the Mediterranean Sea, it is common in the deep waters of the entire western basin; but it is less common in the eastern basin [START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Capapé | Effects of reproductive factors on interrelationships between three deep water sharks from Northern Tunisia (Central Mediterranean)[END_REF][START_REF] Politou | Fisheries resources in the deep waters of the eastern Mediterranean (Greek Ionian Sea)[END_REF][START_REF] Sion | Chondrichthyes species in deep waters of the Mediterranean Sea[END_REF].It is a deep water, usually demersal or benthopelagic species, inhabiting the outer continental shelf with a preference for the upper continental slopes at depths ranging from 100 to 1490 m with most records between 300 to 800 m [START_REF] Compagno | Part 1 -Hexanchiformes to Lamniformes[END_REF][START_REF] Gilat | On the sharks and fishes observed using underwater photography during a deep-water cruise in the eastern Mediterranean[END_REF][START_REF] Guallart | Contribución al conocimiento de la biología y la taxonomía del tiburón batial Centrophorus granulosus[END_REF][START_REF] Baino | Catch composition and abundance of Elasmobranchs based on the MEDITS program[END_REF].

Gulper Sharks are exploited through bycatch by trammel nets, long liners, gillnets and trawlers [START_REF] Costantini | Observations on fishery, feeding habits and reproductive biology of Mustelus mustelus (Chondrichthyes, Triakidae) in Northern Adriatic Sea[END_REF][START_REF] Morey | Elasmobranchs in trammel net fishery associated to marine reserves in the Balearic Islands (NW Mediterranean)[END_REF], and the fact that they are deep-water sharks with late maturity, slow growth and low fecundity makes them susceptible to overexploitation [START_REF] Compagno | Part 1 -Hexanchiformes to Lamniformes[END_REF][START_REF] Stevens | The effects of fishing on sharks, rays, and chimaeras (chondrichthyans), and the implications for marine ecosystems[END_REF]. When caught, these sharks can be discarded or used by bycatch fisheries, marketed as smoked and dried salted for human consumption or processed into fish meals and a source of liver oil for squalene [START_REF] Compagno | Part 1 -Hexanchiformes to Lamniformes[END_REF], a chemopreventive substance that is thought to prevent cancer [START_REF] Smith | Squalene: potential chemopreventive agent[END_REF]. Drastic Gulper Shark population decline was observed in the northeastern Atlantic, off the coast of Portugal, due to target long liners between 1990 and 2004 [START_REF] Gibson | The Conservation of Northeast Atlantic Chondrichthyans: Report of the IUCN Shark Specialist Group Northeast Atlantic Red List Workshop[END_REF].

A few studies on the biology of these deep water sharks were performed in the eastern Mediterranean [START_REF] Golani | Biological aspects of the Gulper shark, Centrophorus granulosus, from the Mediterranean coast of Israel[END_REF][START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF] and no studies were implemented in the coastal waters of Lebanon, the study area. Some studies in the Mediterranean dealt with the analysis of trace metals [START_REF] Hornung | Trace metal content in deep-water sharks from the eastern Mediterranean Sea[END_REF] and polychlorinated biphenyls [START_REF] Storelli | Persistent organochlorine residues and toxic evaluation of polychlorinated biphenyls in sharks from the Mediterranean Sea (Italy)[END_REF] in some organs of Gulper Sharks. Other

Mediterranean studies evaluated the reproduction of this species proving its lecithotrophic nature [START_REF] Guallart | Changes in Composition During Embryo Development of the Gulper Shark, Centrophorus Granulosus (Elasmobranchii, Centrophoridae): An Assessment of Maternalembryonic Nutritional Relationships[END_REF].

The Lebanese fishery is artisanal and traditional, where the most common gear used are trammels, longlines, ‗roundhaul' nets and beach seines. Trawling is legally forbidden although fishing nets with illegal mesh sizes can be vastly bought from the black market [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF].

The majority of the fish caught are bony fish [START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF] and cartilaginous fish landings are particularly low [START_REF] Fowler | Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes : Status Survey: IUCN[END_REF]. However, Gulper Sharks are often observed in Lebanese fish markets as bycatch species that are not discarded and sold as fish filets. It presents a quite low commercial value, ranging from 3 to 5 US dollars per one kilogram. The lack of management measures (and in particular any specific to elasmobranchs) and commercial fishing has created the need to manage the stocks of such elasmobranch species in this region. Due to the vulnerability of this species, immediate actions should be implemented for the management and reduction of its fishing even if the Lebanese artisanal fishing fleet, with a number of 1460 licensed vessels in 2011 [START_REF] Pinello | Fishing fleet data for 2011[END_REF], can be considered small compared to major commercial fisheries in the Mediterranean.

Biological information needed for stock assessment is lacking for many of the Eastern Mediterranean cartilaginous species, including minimum, maximum, average sizes, as well as length-to-weight relationships. Nonetheless, these data are significant for comprehending growth rate, age structure, and other aspects of population dynamics. Size conversions also have a practical value in fisheries. One measure currently in practice is the establishment of minimum size limits and usually a minimum weight. Since sizes must be estimated at sea, means for converting lengths to weights are essential to fishermen. This study being the first for the Lebanese coastal waters, essentially reflects some biological and ecological aspects of the Gulper Shark population in the Lebanese marine waters in order to contribute to a better knowledge of this population. It aims to give insightson spatial, seasonal and depth distribution, reproduction and growth of this species. Length and weight data, sex ratio, length-weight relationships, gonado-somatic and hepato-somatic indices and condition factor are presented and compared to available data from other areas.This study provides a first evaluation of the population health condition and aims, at longer term, to stimulate the protection of such a vulnerable species. Lebanese fishermen have no Global Positioning System (GPS) instruments; however, the depth is provided. The specimens were identified according to the two field identification guides of [START_REF] Bariche | Field identification guide to the living marine resources of the Eastern and Southern Mediterranean[END_REF] and [START_REF] Golani | Fishes of the eastern Mediterranean: Turkish Marine Research Foundation[END_REF]. They were preserved in ice and later frozen at -20°C to be eventually treated in the laboratories of the Lebanese National Council for Scientific

Materials and Methods

Sampling and study area

Research-National Centre for Marine Sciences in Batroun.

Morphometric and biological measurements

Upon treatment, the specimens were observed for external damages and sexed macroscopically by the examination of the male claspers. The external length of the clasper (L C ) in males was measured from the tip of the clasper to the base of the pelvic fin all using a calliper to the nearest millimetre (mm). In the rest of the paper, all lengths and weights were measured to the nearest centimetre (cm) and nearest gram (g), respectively, using an electronic balance and a measuring tape.

Morphometric measurements were performed for each Gulper Shark specimen. The total weight (W T ), total length (L T ), fork length (L F ) and standard length (L S ) were measured prior to dissection. The liver and gonads were removed along with the expanded uteri in the case of a gravid female. The digestive tube was also removed and the eviscerated weight (W E ) was noted.

Hepato-somatic index (I H ) gives useful indication of energy reserves because the liver is an important energy storage in fish [START_REF] Halton | Practical Exercises in Parasitology[END_REF]. Therefore, the weight of the liver (W L ) was measured and used for computation of I H [START_REF] Bulow | Comparisons of two bluegill Populations by Means of the RNA-DNA ratio and Liver-Somatic Index[END_REF][START_REF] Adams | Estimation of largemouth bass, Micropterus salmoides Lacépède, growth using the liver somatic index and physiological variables[END_REF] where:

I H = W L × W T -1 × 100
Gonado-somatic index (I G ) allows to investigate the changes in testis and ovaries weight in relation to the weight of fish. Thus, weight of the gonads (W G ) including weight of testis in males, and oviductal glands, accessory glands, ovary and oviducts in females [START_REF] Gristina | Biological information on Target Species: Sex-determination, Maturation stages and Gravimetric indexes[END_REF] were also measured for computation of I G [START_REF] Bougis | Recherche biométriques sur les rougets (M. barbatus L., M. surmuletus L.)[END_REF] where:

I G = W G × W T -1 × 100
Sexual maturity was determined using the Instruction Manual for the MEDITS Survey -Version 6 (MEDITS, 2012), where the ovoviviparous elasmobranch females were classified among 8 maturity stages (1: Immature; 2: Developing; 3a: Capable to reproduce; 3b: Early pregnancy; 3c:

Mid pregnancy; 3d: Late pregnancy; 4a: Regressing; 4b: Regenerating), and the males among five maturity stages (1: Immature; 2: Developing; 3a: Spawning capable; 3b: Actively spawning; 4: Regressing).

Finally, the condition factor (K) [START_REF] Fulton | The rate of growth of fishes[END_REF] was also computed using total weight (W T ) and total length (L T ), where:

K= W T × L T -3 × 100
The index is commonly used to compare the ‗condition', ‗fatness', or 'well-being' of fish [START_REF] Tesch | Age and growth[END_REF], based on the assumption that heavier fish of a given length are in better condition [START_REF] Froese | Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations[END_REF],

Catch per unit effort

During the PESCA-LIBANO survey, long liners of size 5 hooks and trammel nets of meshes 22, 24, 26, 28, and 30 mm were lowered at specific hauls with predetermined coordinates and depths. Catch per unit effort expressed in kilogram (CPUE kg ) for the Gulper Shark sample caught during the survey (22 individuals) was calculated according to the following:

CPUE kg according to meshed gear equals to the sum of total weights of Gulper Sharks caught in specific meshed gear per total number of Gulper Sharks caught in the same meshed gear considering the specific meshed gear was lowered once with the same effort duration providing an effort of one.

The same method applies to the long liner catches. CPUE kg is commonly used in fisheries science as a relative abundance index for each characteristic area at specific times of the year (seasons) or each specific gear.

Regressions and statistical analyses

The statistical software ‗R project' (R Development Core Team, 2014) was used for all regressions and statistical analyses, and Quantum Geographic Information System (qGIS) software (QGIS Development Team, 2012)was used for the maps.

The total length and total weight were used to produce a length-weight relationship in a nonlinear power regression (W T =aL T b ) [START_REF] Lecren | The Length-Weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis)[END_REF] where ‗a' and ‗b' are the parameters to estimate using the nls function . The coefficient of determination (r 2 ) was used to evaluate the quality of the model.Nonlinear regressions were used to represent any regression of weight on length because any weights will scale to the cubic power of length [START_REF] Froese | Cube law, condition factor and weight-length relationships: history, meta-analysis and recommendations[END_REF]. In addition, statistical comparison of weight-length relationships between sexes was performed by applying an ANCOVA test using the anova function. A Shapiro-Wilk normality test was used to test for the normality of the sample using the shapiro.test function, and the Mann-Whitney U test was used to test for differences in length and weight between males and females using the wilcox.test function. A Mann-Whitney U test was also used to examine the mean differences between total length and total weight according to type of gear used. Moreover, a Kruskal-Wallis test was used to examine the differences between total length, total weight and gonado-somatic index according to sexual maturity and between the biological indices (I G , I H and K) according to season using the kruskal.test function. A post-hoc Nemenyi test was used for pairwise multiple comparisons of the ranked dataafter significant results from the Kruskal-Wallis tests using the posthoc.kruskal.nemenyi.test function of the PMCMR package. The sex ratio was calculated for the whole sample and compared to the 1:1 proportion using a Chi-square test [START_REF] Zar | Biostatistical analysis[END_REF] using the chisq.test function. A Chi-square test was also used to examine the relationships between sex and depth and between maturity stage and depth. The anova.2way.unbalanced function [START_REF] Anderson | An empirical comparison of permutation methods for tests of partial regression coefficients in a linear model[END_REF][START_REF] Legendre | Distance-based redundancy analysis: testing multispecies responses in multifactorial ecological experiments[END_REF] was used to perform a two-way unbalanced ANOVA on the total weights according to several factors. Two factor modalities were used for region (north; south), season (cold: spring and winter; hot: summer and autumn),

depth ([0,400[; [400,600]), and sexual maturity (mature; immature) in the latter analysis. trammel nets) and 3 modalities of depth ([0-200[,[200-400[ and[400-600[). Results are presented on the first two principal components representing 48.55% of the total variance.

Results

Morphometric measurements and depth distribution

A total of 38 individuals (18 females and 20 males) of Gulper Sharks ranging from 45 to 94 cm in L T (meanL T ± SD = 80.64 ± 9.97 cm, N=38) and from 870 to 6700 g in W T (meanW T ± SD = 3791 ± 1312.58 g, N=38) were studied (Table 20). Moreover, significant differences were observed in the total length and total weight distributions between male and female individuals (L T : Mann-Whitney U test, U=1, N Male 1=20, N Female 2=18, P<0.02; W T : Mann-Whitney U test, U=0.5, N Male 1=20, N Female 2=18, P<0.02). The sampled individuals were caught at depths ranging from 115 to 600 m. All male individuals were observed at depths greater than 400 m, whereas females were observed throughout the above mentioned range. Moreover, the majority of female individuals (61%) was observed at depth class of 200 -300 m and that of male individuals (47%) at depth class of 500 -600 m; females were also observed at depths ranging from 500 to 600 m and no individuals were observed at depth class of 300 -400 m (Figure 34). Significant differences were observed between the male and female distributions according to depth (Chi-square test, X25=16.87, P=0.0048); however, no significant differences were observed between mature and immature individuals according to depth (Chi-square test, X25=10.53, P=0.0616). In addition, significant differences in weight distributions were observed according to depth (Kruskal-Wallis test, H22=12.99, P=0.0015), with significant differences between the depth classes [200-400[and [400-600] (Nemenyi test, P<0.05).

Spatial distribution and gear

Twenty-two individuals of the Gulper Shark sample were caught using long liners and trammel nets of 26 and 30 mm meshes in the PESCA-Libano survey. The CPUE kg for the survey catches displayed the highest catches using trammel nets of the two meshes in the north and south with CPUE kg ranging from 4.9 to 5.45 kg per unit effort at depths ranging from 120 to 200 m during the spring and summer seasons. Relatively lower CPUE kg were observed in the south for longliner catches at depths ranging from 450 to 600 m in spring (Figure 35). In addition, the larger individuals of Gulper Sharks in total length and total weight (Figure 36)

were caught by trammel nets than long liners, and significant differences were observed between the total lengths and weights according to the type of gear used (L T : Mann-Whitney U test, U=27.5,N Longline 1=26, N Trammel Net 2=12, P<0.02;W T :Mann-Whitney U test, U=30.5,N Longline 1=26, N Trammel Net 2=12, P<0.02). However, a wider size range was observed to be caught when using long liners (Figure 36). Moreover, a significant difference in terms of number of individuals caught by sex was also observed between males and females according to gear used (Chi-square test, X21=16.52, P=4.804×10 -05 ). All males were caught using long liners and the majority of females were caught using trammel nets (Figure 34).

Sex ratio, length-frequency distribution and length-weight relationship

The sex ratio was calculated to be 1.11, lacked significant bias, and was not significantly different from 1:1 (Chi-square test, X21=0.11, P=0.7456). The length-frequency distribution shows the absence of females in the size classes lower than 80 cm and their domination in the larger size classes (80 and 90 cm). On the contrary, males occupied the smaller size classes (40 to 80 cm) and showed few numbers in the 80 cm size class and were absent in the largest size class (90 cm). Moreover, the majority of males (75%) occupied the 70 cm size class and the majority of females (72%) occupied the 80 cm size class (Figure 37). Females: W T = 0.243 L T 2.219 , r 2 = 0.45, N = 17) (Figure 38). These new relationships can be valid for the sizes ranging between 70 and 85 cm for males and 85 and 95 cm for females.

Sexual maturity and biological indices

All maturity stages were observed during the study period except the ‗developing' (stage: 2), ‗capable to reproduce' (stage: 3a), and ‗regenerating' stages for females and ‗regressing' (stage: 4) stage for males. Significant differences were observed between the weight and length distributions of the Gulper Shark individuals according to each maturity stage for male individuals and for the whole sample (Whole sample -L T : Kruskal-Wallis test, H26=26.25, P=0.00019; W T : Kruskal-Wallis test, H26=26.29, P=0.00019 -Male sample -L T : Kruskal-Wallis test, H23=8.16, P=0.0429; W T : Kruskal-Wallis test, H23=8.81, P=0.0319). Nevertheless, no significant differences were observed for the same distributions according to each maturity stage for female individuals (L T : Kruskal-Wallis test, H24=7.12, P=0.1298; W T : Kruskal-Wallis test, H24=7.12, P=0.1295). The post hoc Nemenyi test gave significant differences of total length and total weight means according to sexual maturity between the maturity stages ‗2' and ‗3b' (Nemenyi test, P<0.05) for the male sample and the stages ‗2' and ‗3c' (Nemenyi test, P<0.05) and ‗3d' and ‗3c' (Nemenyi test, P<0.05) for the whole sample. The majority of male Gulper Sharks in the study period were actively spawning (stage: 3b) with sperm being released out of the cloaca upon pressure. However, the highest mean values of I G were observed in stage 3a where the testes were greatly enlarged and full of sperm (Figure 39).

In addition, the majority of observed females were in mid pregnancy (stage: 3c) showing the highest values of I G . Relatively lower I G values were observed in early (stage: 3b) and late (stage: 3d) pregnancies (Figure 39). No significant relationship was observed between the I G according to the sexual maturity stages in each male and female samples (Male sample -I G : Kruskal-Wallis test, H22=3.07, P=0.3806; Female sample -I G : Kruskal-Wallis test, H23=6.77, P=0.1488).

However, a significant relationship was observed between I G according to the sexual maturity stages in the whole sample with significant differences between stages ‗2' and ‗3c' and between ‗3c' and ‗3d' (Whole sample -I G : Kruskal-Wallis test, H25=22.79, P=0.0009; Nemenyi test, P<0.05). Moreover, no significant relationships were observed between clasper lengths of male Gulper Sharks and total length (Pearson rank correlation, rp = 0.14, N=18, P>0.01). The smallest mature male (L T = 73.5 cm) had a clasper length of 75 mm (Figure 40). The male gonad weight ranged from 2 to 100 g and showed no significant increase with total length (Pearson rank correlation, rp = 0.35, N=18, P>0.01) (Figure 40). Figure 41: Boxplots representing the hepato-somatic index, gonado-somatic index, and condition factor of the Gulper Shark male individuals (a) and female individuals (b) according to seasons during the study period (black line in box: median; line outside box: general mean between seasons; large points in box: mean in each season; small points outside box: outliers; ‗N' is the number of Gulper Sharks in the sample)

Two-way Unbalanced ANOVA and Principal Component Analysis (PCA)

Regarding the two-way unbalanced ANOVA, no significant double interaction between all 2x2 factors was observed (Two-way ANOVA, P>0.05). The PCA showed that the main numerical variables contributing to axis 1 were W T , L F , L S , W G , W E , and I G , whereas those contributing to axis 2 were W L , and I H . The main categorical variables contributing to axis 1 were ‗Depth', ‗Gear', ‗Sex', and ‗Sexual maturity', whereas those contributing to axis 2 were ‗Season' and ‗Region'. In addition, mature females showed to be caught by trammel nets at depths between 0 and 400 m have the largest morphometrics and gonad weights opposite to the immature males on the negative side of axis 1. Regarding axis 2, the largest livers were found in individuals caught during the spring season in the southern region of Lebanon opposite to those caught during the winter and summer seasons in the northern region on the negative side of the axis (Figure 42).

Discussion

Several factors influence population dynamics and maintenance of the population. This work presents the factors which can be importantfor the future management of the Gulper Shark, Centrophorus granulosus.

Spatial and seasonal distribution, habitat and life cycle

Muñoz-Chapuli (1984) hypothesized that demersal sharks are segregated by size and sex in the Atlantic. Based on bathymetric distributions of a number of species, including Centrophorus granulosus and Galeus melastomus, he hypothesized that such sharks have nursery grounds on the continental shelf to which pregnant females migrate, while adult males remain at greater depths. [START_REF] Golani | Biological aspects of the Gulper shark, Centrophorus granulosus, from the Mediterranean coast of Israel[END_REF] confirmed this assumption for Gulper Shark by observing that the males of this species dominated intermediate depths (550-800 m) and females dominated shallow depths (200-400 m) along the coast of Israel. These results agree with those observed in this study and confirm the probable bathymetric sexual segregation of this species.

The CPUE kg results suggests that the Gulper Sharks are present northern and southern of Lebanon. In addition, the maximum observed CPUE kg value (5.45 kg/unit effort) in summer using trammel nets of mesh 26 mm was higher than that observed in the Ionian Sea for the same species using a commercial trawler (in kg/hr) at a higher depth during the autumn season [START_REF] Politou | Fisheries resources in the deep waters of the eastern Mediterranean (Greek Ionian Sea)[END_REF]. This result can be attributed to type of gear utilized, method of CPUE kg estimation and seasonal depth distribution of this species. In addition, the higher CPUE kg observed in the trammel net catches compared to those of the long liner catches implies that trammel nets constitute a more important mean for demersal shark bycatch than long liners according to this study. However, [START_REF] Stergiou | Gillnet and longlines fisheries in Cyclades waters (Aegean Sea): species composition and gear competition[END_REF] showed that bottom long liners incidentally bring several demersal species, such as, Mustelus sp., Squalus sp., Torpedo sp. and some Rajidae; since Gulper Sharks are demersal, it is obvious that bottom long liners also generate a significant mean for the bycatch for this species. Furthermore, the impact of gear selectivity is also shown in this study, where trammel nets caught larger individuals but with a narrower length range than long liners that caught smaller individuals with a wider length range.

A similar pattern for gear selectivity was observed for several elasmobranch species southern of Portugal [START_REF] Coelho | Semi-pelagic longline and trammel net elasmobranch catches in southern Portugal: Catch composition, catch rates and discards[END_REF].

Size and growth

The maximum length recorded for Gulper Sharks in this study (94 cm) correlates with that observed along the coast of Crete [START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF] and the coast of Israel [START_REF] Golani | Biological aspects of the Gulper shark, Centrophorus granulosus, from the Mediterranean coast of Israel[END_REF], both of which are located in the eastern Mediterranean, where the maximum total lengths observed were 95 and 96.7 cm respectively. However, the highest total length observed in this work was smaller than that observed along the coasts of Tunisia, western

Mediterranean, where a total length of 128 cm was recorded for the same species [START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Capapé | Effects of reproductive factors on interrelationships between three deep water sharks from Northern Tunisia (Central Mediterranean)[END_REF]. This variation in maximum total lengths between eastern and western Mediterranean can be attributed to the fact that shallow waters in the eastern Mediterranean are known to be oligotrophic [START_REF] Abi Saab | A study of the annual cycle of phytoplanctonic Population in the Palm Island Nature Reserve, Lebanon[END_REF][START_REF] Ignatiades | Scaling the trophic status of the Aegean Sea, eastern Mediterranean[END_REF] which may have affected the physiological status and growth of this species.

The negative allometric growth (b<3) revealed in this study for both males and females of the studied sample comes in agreement with that observed by [START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF] for adult Gulper Sharkspecimens along the Tunisian coast. Nevertheless, the latter author revealed that young and sub-mature Gulper Sharks showed positive allometric growth in the Tunisian waters, and the same positive pattern was also observed off the island of Crete [START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF] and in Antalya Bay [START_REF] Guven | Length-weight relationships of sharks in Antalya Bay, eastern Mediterranean[END_REF] for adults of the same species. This variation in -b‖ coefficients can be probably due to the domination of large mature individuals in the male and female samples and the absence of a wide length range in the female sample of the studied Gulper Sharks. Moreover, the important difference in adult Gulper Sharks allometric growth parameters between the present study and that off the island of Crete can also be attributed to the environment and physiological status of the Gulper Sharks in both regions. In all cases, a sample with a wide length range for both sexes should be analysed to attain a more precise estimation of allometric parameters.

The smallest mature Gulper Shark male observed in this study was smaller than the smallest mature female.This fact agrees with other studies [START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Fischer | Fiches FAO d'identification des espèces pour les besoins de la pêche. Méditerranée et mer Noire. Zone de Pêche[END_REF][START_REF] Guallart | Contribución al conocimiento de la biología y la taxonomía del tiburón batial Centrophorus granulosus[END_REF] which stated that male Gulper Sharks mature at a smaller size than females. Although [START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF] stated that gonad weights increase rapidly with total length for Gulper Sharks, no significant relationship between male gonad weight and total length was observed in this study. This can be attributed to the domination of mature male individuals and the absence of small to medium-sized individuals from the sample, which was also revealed by the close clasper lengths according to the range of male total lengths.

Reproduction and biological indices

The presence of pregnant females at various stages could indicate that the Levantine area along the coast of Lebanon is a reproductive area for this species. Moreover, several previous studies noted that gravid Gulper Shark females carried one single embryo or a single large egg [START_REF] Ranzi | Le base fisio-morphologiche dello sviluppo embrionale dei Selaci. Parte I (The physiomorphological basis of the embryonic development in Selachii. Part I)[END_REF][START_REF] Tortonese | Leptocardia, Ciclostomata, Selachii, Fauna d'Italia[END_REF][START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Guallart | Contribución al conocimiento de la biología y la taxonomía del tiburón batial Centrophorus granulosus[END_REF]. However, this was not the case in one of the Gulper Shark females in this study that carried two embryos. The sizes of all the embryos in this study coincide with those at birth noted by several authors for this species [START_REF] Fischer | Fiches FAO d'identification des espèces pour les besoins de la pêche. Méditerranée et mer Noire. Zone de Pêche[END_REF][START_REF] Guallart | Changes in Composition During Embryo Development of the Gulper Shark, Centrophorus Granulosus (Elasmobranchii, Centrophoridae): An Assessment of Maternalembryonic Nutritional Relationships[END_REF], which indicates upcoming parturition. In addition, the presence of two pups per litter in this female can suggest that it might belong to a synonymous species, Centrophorus uyato Rafinesque 1810, as it has been reported in the Mediterranean Sea [START_REF] Guallart | Centrophorus granulosus. In The IUCN Red List of Threatened Species[END_REF]. This latter species is the closest to Centrophorus granulosus in the Mediterranean Sea and is described as ovoviviparous with a maximum of two pups per litter [START_REF] Mclaughlin | Reproductive biology of Centrophorus cf. uyato from the Cayman Trench, Jamaica[END_REF]. Nevertheless, this issue of two species present in the Mediterranean presents a taxonomically controversial hypothesis because most Mediterranean authors note that there is only one species of Centrophorus (Centrophorus granulosus) in the Mediterranean Sea [START_REF] Tortonese | The squaliforms on the Ligurian Sea: a revised list with notes[END_REF][START_REF] Rancurel | Programme de recherche et d'études des populations des requins de profondeur sur les côtes de Corse[END_REF][START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Muñoz-Chapuli | Review of the Centrophorus sharks (Elamobranchii, Squalidae) of the eastern Atlantic[END_REF][START_REF] Guallart | Contribución al conocimiento de la biología y la taxonomía del tiburón batial Centrophorus granulosus[END_REF]. Another explanatory hypothesis could be that a physiological stress caused the ovulation of two mature oocytes and their fertilization at probably different times. This can be supported by the fact that oocytes in the ovaries continue to develop even during gestation, since most pregnant females carry large embryos and large oocytes simultaneously, suggesting that ovulation can occur soon after parturition [START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF][START_REF] Guallart | Changes in Composition During Embryo Development of the Gulper Shark, Centrophorus Granulosus (Elasmobranchii, Centrophoridae): An Assessment of Maternalembryonic Nutritional Relationships[END_REF] or even before parturition as hypothesized in this paper.

Concerning the variation of biological indices, it is obvious that I G reaches its highest values in early and mid-pregnancy for females and prior to spawning in males due to the formation of well-filled rounded uteri with yolk content in females and greatly enlarged testes in males, all of which can increase gonad weight and positively affect I G.

The lower mean values of I H in the female sample throughout the study period could be due to the domination of pregnant females, which explains the high I G values in spring and autumn.

Moreover, it has been recorded that I H decreases during maturation and pregnancy for some elasmobranches [START_REF] Yano | Reproductive Biology of the Black Dogfish, Centroscyllium fabricii, collected from waters off Western Greenland[END_REF][START_REF] Demirhan | Maturity and reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (Northeastern Mediterranean)[END_REF]. Therefore, this decline in I H for females, especially in spring, along with the highest I G values, could imply that Gulper Shark females metabolized liver reserves during gestation. In reverse, the presence of high I H and I G values for male Gulper Sharks in spring coincides with what was observed by [START_REF] Capapé | Contribution à la biologie des Rajidae des côtes tunisiennes. 21. Raja asterias, Delaroche, 1809: relations taille-poids, taille-poids du foie, taille-poids des gonades. Coefficients de condition. Rapports hépatosomatique et gonadosomatique[END_REF] for Raja asterias where an increase in the gonad weight was accompanied by a storage of substances in the liver. This could indicate a sexual dimorphism in liver weight and reserve metabolism between male and female Gulper Sharks. In addition, according to the variation of I H in both male and female Gulper Sharks and the fact that this species has a relatively long gestation period of two years, it is apparent that this long gestation involves metabolic energy expenses for a longer period [START_REF] Guallart | Changes in Composition During Embryo Development of the Gulper Shark, Centrophorus Granulosus (Elasmobranchii, Centrophoridae): An Assessment of Maternalembryonic Nutritional Relationships[END_REF] and the size of the liver changes according to reproductive stage, an observation which was also described for a squalid by [START_REF] Yano | Reproductive Biology of the Black Dogfish, Centroscyllium fabricii, collected from waters off Western Greenland[END_REF].

The condition factor can provide information on the general condition of fishes in the habitat they live, as well as indicate phenomena such as spawning period, alterations in population density and feeding conditions [START_REF] Braga | Estudo entre fator de condição e relação peso/comprimento para alguns peixes marinhos[END_REF]. Regarding the condition factor of the Gulper Shark sample, the almost constant values for the males throughout the study period was indicative of an evident wellness among the male population and could indicate a lack of any physiological or environmental factor affecting the stock. Nonetheless, the wide fluctuations in K of the females could be due to the physiological stress caused by gestation or mating, as some male or female elasmobranches display low condition factors indicating probable stress during mating season [START_REF] Loefer | Life history of the Atlantic sharpnose shark (Rhizoprionodon terraenovae)(Richardson, 1836) off the southeastern United States[END_REF].

Finally, this study draws attention to the Gulper Shark population along the Lebanese coast, as scarce are the studies that are performed about this species in the Levantine basin. This species is majorly exploited as bycatch by long liners and trammel nets, at times discarded or sold in fisheries with low cost. Thus, management measures should be implemented to prevent the vast exploitation of this elasmobranch group as bycatch that is classified internationally as

Vulnerable. Laws should be applied to decrease the exploitation of this species. The data presented in this study will be useful for the ongoing assessment of populations, fishery stock, ecological risk, and species extinction risk.

Chapter VII: General discussion, conclusion and perspectives

The present study is the first of its sort along the Lebanese coast. Its main interest is to contribute to a better knowledge of the status of chondrichthyans in this area. These species are subject to various threats worldwide, especially in the Mediterranean Sea, which is considered one of the three hotspots where the diversity of elasmobranchs is threatened [START_REF] Dulvy | Extinction risk and conservation of the world's sharks and rays[END_REF].

Overfishing, bycatch, and habitat loss are the major pressures affecting this fish class [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. Its presence was already described for most regions of the Mediterranean except in its eastern basin along the Lebanese coast. The fact that these fishes are exploited in this region urges the need to implement management measures of their fishing and decrees to protect them.

In this context, two main aspects are discussed:

-The diversity and distribution of these fish along the Lebanese coast -The life-history traits of two exploited elasmobranchs in the area

Elasmobranchs: Presence, diversity and fisheries in Lebanon

Presence and diversity

Cartilaginous fishes are demanded worldwide for their highly valuable parts (e.g. fins); thus, fisheries targeting them expanded [START_REF] Barausse | The role of fisheries and the environment in driving the decline of elasmobranchs in the northern Adriatic Sea[END_REF]. No major fisheries targeting chondrichthyans are present in the Mediterranean Sea; nonetheless, its artisanal and traditional fisheries, mixed species fisheries, and the trawlers of some regions have posed a major source of chondrichthyans bycatch [START_REF] Caddy | Some future perspectives for assessment management of Mediterranean fisheries[END_REF][START_REF] Musick | Management techniques for elasmobranch fisheries[END_REF]Stevens et al., 2005;[START_REF] Walker | Regional Overviews: Northeast Atlantic (including Mediterranean and Black Sea). In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF]. Elasmobranchs also constitute bycatch in traditional tuna traps [START_REF] Storai | Bycatch of large elasmobranchs in the traditional tuna traps (tonnare) of Sardinia from 1990 to 2009[END_REF].

Examples for that are the threats posed by artisanal Lebanese fishermen on chondrichthyans along the coast of Lebanon, where these fish are either targeted by bottom longlines or incidentally caught.

During the course of this study, a total of 25 cartilaginous fish species were recorded along the coast at several depths ranging from 10 to 600 m. The number of species constitutes almost 30% of all species found in the Mediterranean, and it is less than that recorded in several regions of the Eastern Mediterranean, such as, Cyprus (45 species) [START_REF] Hadjichristophorou | Chondrichthyes in Cyprus[END_REF], Turkey (63 species) [START_REF] Bilecenoglu | An updated checklist of the marine fishes of Turkey[END_REF], Syria (38 species) [START_REF] Ali | Sharks and rays in Syrian sea waters (in Arabic with abstract in English)[END_REF][START_REF] Saad | Liste commentée des Chondrichthyens de Syrie (Méditerranée orientale)[END_REF] and Israel [START_REF] Golani | Cartilaginous fishes of the Mediterranean coast of Israel[END_REF]. More chondrichthyans (44 species) were also recorded in studies performed along the Lebanese coast around 5 decades ago by [START_REF] George | The Fishes of the Coastal Waters of Lebanon[END_REF], [START_REF] George | On the occurrence Scomberomorus commerson (Lacépède) in St George Bay, Lebanon[END_REF], George and Athanassiou (1966a), George and Athanassiou (1966b), George and[START_REF] George | A two year study of the fishes appearing in the seine fishery of St George Bay[END_REF][START_REF] George | The presence of a third species of the genus Sphyraena (Pisces) in the marine water waters of Lebanon[END_REF]. Even less chondrichthyans ( 22) were recorded in a more recent study [START_REF] Mouneimne | Poissons des côtes du Liban (Méditerranée Orientale)[END_REF]2002). The seasonal and regional fluctuations and peaks of diversity indices reflects the biodiversity of chondrichthyans along the Lebanese coast.

This diversity is indispensable to maintain the stability of the ecosystem (considering elasmobranchs as top predators) and protect the overall environmental quality [START_REF] Ehrlich | Biodiversity Studies: Science and Policy[END_REF].

Abundance index

The analysis of the Catch Per Unit Effort (CPUE) and total weight variation of the elasmobranchs observed during this study provided indications of the spatio-temporal variation of their distribution and abundance. This variation could be attributed to (a) environmental or (b)

human effects. The nature of Lebanese water, availability of prey, daily and seasonal movements for breeding and feeding, as well as, fishing techniques and the depths at fishing can explain the variation in distribution and abundance of these fish according to examples in [START_REF] Bianchi | Study of the demersal assemblages of the continental shelf and upper slope off Congo and Gabon, based on the trawl surveys of the RV -Dr. Fridtjof Nansen‖[END_REF], [START_REF] Koslow | Community structure in North Atlantic deep-sea fishes[END_REF], and [START_REF] Gordon | Environmental and biological aspects of slope dwelling fishes of the North Atlantic[END_REF]. Due to the uniqueness of this study in the region, no trend could be estimated concerning the variation in abundance and biomass of cartilaginous fish inhabiting the coastal waters. Therefore, all cartilaginous fish catches (whether incidental or targeted) should be reported for proper future statistical estimation of spatio-temporal trends for a better management and protection. Furthermore, the present study used information from scientific surveys and commercial fisheries. This method could determine spatial and temporal distributions of exploited fish, such as, the case of the spatio-temporal distribution (estimated from the CPUE of survey and fishery data) of the recruiting and spawning Celtic Sea whiting [START_REF] Verdoit | Are commercial logbook and scientific CPUE data useful for characterizing the spatial and seasonal distribution of exploited populations? The case of the Celtic Sea whiting[END_REF]. Commercial data has an advantage of not causing additional mortality, but it is less precise due to the lack of Global Positioning Systems (GPS). Scientific data is standardized. The presence of complete data sets in the latter study enabled the proper estimation of CPUE from both scientific survey and fishery data. Some gear used in the survey was not uniformly lowered throughout the coast, at all depth strata, and all seasons; for instance, longlines were only deployed in the south due to lack of financial support (low funds as longlines break easily, their mending is expensive, and sometimes bait was not available) and political reasons (conflicts arose in Tripoli in the north during the sampling period). Moreover, no gear was lowered during the autumn season. Although the data collected was limited, the results of the survey were interesting. The quantity of elasmobranchs caught during this survey indicates that proper management techniques should be implemented. Future surveys should be carried out in a more uniform manner regarding seasons, gear used, and distribution of hauls for a better estimation and more clarified species richness and wider CPUE indications.

Spatio-temporal variations

Regarding the spatio-temporal diversity and distribution of this fish class, both showed seasonal variations and slight regional differences in this study. Habitat selection by elasmobranchs depends on several biotic and abiotic factors. Temperature and depth account for much of the spatial variation in the species composition of demersal fish communities. Temperature is the key abiotic factor that controls the rate of metabolism and growth and prey abundance is the key biotic factor that influences habitat quality [START_REF] Swain | Change in habitat associations and geographic distribution of thorny skate (Amblyraja radiata) in the southern Gulf of St Lawrence: density-dependent habitat selection or response to environmental change[END_REF]. In Shark Bay, Australia, a higher density of elasmobranchs was observed during the warm seasons, probably driven by thermoregulation [START_REF] Vaudo | Spatiotemporal variability in a sandflat elasmobranch fauna in Shark Bay, Australia[END_REF]. Furthermore, based on 32-year of monitoring by a bottom-trawl survey, Southern Gulf of St Lawrence, Canada, the geographic range of the Thorny Skate (Amblyraja radiata (Donovan, 1808)) contracted sharply and distribution shifted into a narrow band of warm deep waters. However, these changes in skate distribution coincided with a decline in skate biomass and a cooling of bottom waters. Therefore, this contraction in the geographic range of skates was a density-dependent response, more closely related to the decline in skate abundance than to the change in environmental conditions [START_REF] Swain | Change in habitat associations and geographic distribution of thorny skate (Amblyraja radiata) in the southern Gulf of St Lawrence: density-dependent habitat selection or response to environmental change[END_REF].

Habitat structure can also influence nearshore cartilaginous and bony fish assemblages. For instance, the occurrence of skates and rays in Babadillimani bight in the northeastern Mediterranean showed sediment preferences as investigated by [START_REF] Yeldan | Sediment structure and occurence of skates and rays inhabiting in Babadillimani bight located in northeastern Mediterranean[END_REF]. Skates in the latter region preferred highly silty bottoms while rays were more densely distributed along shallower areas and sandy silt. Furthermore, [START_REF] Schlaff | Influence of environmental factors on shark and ray movement, behaviour and habitat use: a review[END_REF] reviewed the influence of environmental factors on shark and ray movement, behavior and habitat use. These authors showed that temperature, salinity, dissolved oxygen, tide, photoperiod, barometric pressure and pH have also been documented to act as drivers of movement in shark and ray species. In this context, studying abiotic factors, bathymetric structure of the bottoms and associating sediment types with the presence of chondrichthyans could also provide more information about variation in the observed spatial distribution. The lack of bathymetric data, bottom and sediment type along the Lebanese coast was faced during the course of this study. Having been able to manipulate survey sampling conditions, bottom sampling should have been also carried out for every haul in order to associate the presence of the elasmobranchs caught to the bottom structure.

Such additional sampling was not performed during the survey due to lack of time and specific (material and humans) resources in the vessels hired.

Marine Protected Areas

The results of diversity in this study can encourage to a longer term the implementation of Marine Protected Areas (MPAs) along the coast. Although two nature reserves are already present along the Lebanese coast ( 43) based on scientific assessments [START_REF] Bariche | Marine reserve network for the Lebanese waters[END_REF]ACCOBAMS, 2010;OCEANA MedNet, 2011), field surveys and richness. The results of this study can add basic data to stimulate the increase of MPAs along the coast, aiming for further and wider coastal protection and sustainable management. The increased presence of MPAs along the coast can stimulate the fishing management in that protected area, and subsequently enhance the protection of susceptible marine organisms, such as, chondrichthyans.

MPAs constitute valuable assets that aid in the sustainable use of fisheries resources and prohibit fishing activities during breeding or nursery seasons in order to allow the restoration of important of susceptible resources. Moreover, it is also important to stimulate the creation of MPA networks to enable the connectivity between MPAs. According to the fact that most fishing operations take place in the north and the results obtained on the diversity of elasmobranchs in Lebanon indicating that higher diversity and abundance were observed in the south, we can hypothesize that elasmobranch diversity is already altered in the north by fishing. Thus, we can suggest that MPAs should be enforced in the northern areas of Lebanon and also the implementation of a large MPA in the south in order to preserve this high diversity. In addition, we could propose the implementation of measures in the marine areas around the two Lebanese coastal nature reserves whose existence makes these measures easier to implement.

Species identification

The identification and reporting of cartilaginous fish upon catch is almost lacking in Lebanon with the absence of scientists working in this field. Fishermen have general names for these fish, sometimes giving one name for several species with almost similar morphology. This have been observed in several developing countries worldwide. These countries struggle to identify species caught. They only specify the species and the genus for 17 percent of the cartilaginous fish caught, but store 45 percent of the catch at the highest level of classification. In contrast, developed countries identify the species and the genus of 72 percent of the catches and record only 7 percent of their catch in the class level (Figure 44). Many developing countries complain of a lack of taxonomists or scientists and officials trained in monitoring and evaluating these species, with inadequate access to basic tools for shark identification (FAO, 2014). In this context, DNA barcoding constitutes a good method that can revolutionize species identification and decrease problems related to misidentification. Using molecular techniques to identify shark species and their body parts from specimens morphologically difficult to identify, or to confirm morphological species identification has become an accepted technique [START_REF] Shivji | Genetic identification of pelagic shark body parts for the conservation and trade monitoring[END_REF]Clarke et al., 2006a;Holmes et al., 2009a). DNA barcoding has also been applied to elasmobranch products. This method has demonstrated high levels of fraudulent substitutions in sales of sharks [START_REF] Barbuto | DNA barcoding reveals fraudulent substitutions in shark seafood products: The Italian case of -palombo‖ (Mustelus spp.)[END_REF], identified endangered species in confiscated shark fins (Holmes et al., 2009b) and revealed the sale of endangered sawfish as -shark‖ fillets in markets in Brazil [START_REF] Melo Palmeira | Commercialization of a critically endangered species (largetooth sawfish, Pristis perotteti) in fish markets of northern Brazil: Authenticity by DNA analysis[END_REF].

Figure 44: Shark catches reported by developed and developing countries classified by according to the taxonomic levels (FAO, 2014)

Lack of fishing logbooks

In addition, the lack of logbooks containing all catch information in Lebanese fisheries is one reason for the fact that CPUE was not estimated for the elasmobranchs collected from fisheries.

Instead, the only reflection for biomass was the total weight of the collected elasmobranchs. No vessel information or catch duration is noted in professional Lebanese fisheries. Lebanese artisanal fishermen collect their catches and mix them with other catches in local fisheries to be sold during daily auctions or to walking-by customers. Therefore, estimating the CPUE in such conditions and reporting the fish species landed (whether bony or cartilaginous) is difficult and almost impossible.

Fisheries

Moreover, this study shows that the artisanal fisheries along the Lebanese coast are exploiting chondrichthyans to an extent. Elasmobranchs are shown to be observed in fisheries, especially in Tripoli (northern Lebanon) all year long, where the highest percentage of navigation licenses and the majority of fishing operations occur in the latter region [START_REF] Majdalani | Census of Lebanese Fishing Vessels and Fishing Facilities[END_REF]. Being top predators, overexploitation of elasmobranchs can have a damaging effect on the whole ecosystem by disturbing the complex equilibrium provided by these predators. Elasmobranchs can be categorized by species maximum length to determine susceptibility of decline under exploitation. Generally, species greater than 100 cm are characterized by life-history and population traits that place them at greater risk of population decline [START_REF] Frisk | Estimation and analysis of biological parameters in elasmobranch fishes: a comparative life history study[END_REF].

Elasmobranch fishing and bycatch remain little known and poorly characterized especially along the Lebanese coast. Elasmobranchs taken as bycatch in fisheries targeting other species could be eradicated long before appropriate management policies would be implemented [START_REF] Walker | Can shark resources be harvested sustainably? A question revisited with a review of shark fisheries[END_REF].

Soon after heavy exploitation, the catch rates of elasmobranchs can rapidly decrease [START_REF] Bonfil | Overview of World Elasmobranch Fisheries[END_REF]. Examples of elasmobranch overexploitation have already been observed in several areas of the world: common skate (Raja batis) is now locally extinct from the Irish Sea [START_REF] Walker | Can shark resources be harvested sustainably? A question revisited with a review of shark fisheries[END_REF][START_REF] Dulvy | Fishery stability, local extinctions, and shifts in community structure in skates[END_REF]; Thorny Skate (Amblyraja radiata) in the southern Gulf of St. Lawrence is currently at the lowest biomass level ever observed [START_REF] Swain | Change in habitat associations and geographic distribution of thorny skate (Amblyraja radiata) in the southern Gulf of St Lawrence: density-dependent habitat selection or response to environmental change[END_REF]; White Skate (Rostroraja alba) and longnose skate (Dipturus oxyrhinchus) are now locally extinct from the Irish Sea and Bristol Channel areas [START_REF] Dulvy | Fishery stability, local extinctions, and shifts in community structure in skates[END_REF]. Therefore, the identification of the spatio-temporal distribution and diversity, habitat selection and consistent estimations of fishing and discard mortality of cartilaginous fish species along the Lebanese coast are of high importance in understanding the impact of fisheries on this fish class in a poorly studied area of the Mediterranean.

Length-weight relationships

This study also presents some length-weight data of 8 elasmobranchs, some of which having a threatened status in the Red List of the International Union for the Conservation of Nature (IUCN). The estimation of length-weight relationships has a very important practical value in fisheries management. Along the coast of Lebanon, basic biological data needed for elasmobranch stock assessment are lacking. Length-weight relationships are important for understanding growth rate, age structure, some aspects of population dynamics, as well as, constituting a tool to protect and conserve this fish class. Some length-weight relationships in this study showed a similar trend as some for the same species in different areas of the Eastern Mediterranean; however, some even showed an opposite pattern. In this context, data from different regions should be combined to estimate length-weight relationships of several threatened elasmobranchs that can be used for a wider area. Therefore, the length-weight relationships presented in this study are only useful and efficient for the elasmobranch populations inhabiting the Lebanese coast and for the specific length ranges and sexes investigated. These data can stimulate laws to limit overexploitation of these fishes through direct fishing and bycatch by establishing a minimum catch weight limit and abiding to these weights when the lengths are estimated at sea. Furthermore, seasonal length-weight relationships should be also estimated for the investigation of probable variation in growth by seasons.

Length-weight should also be estimated according to maturity stage as differences could be observed between the growths in different stages; for example, differences in length-weight parameters were observed between adult, sub-mature and juveniles of the Gulper Shark, Centrophorus granulosus, along the coast of Tunisia [START_REF] Capapé | Nouvelle description de Centrophorus granulosus (Schneider, 1801) (Pisces, Squalidae). Données sur la biologie de la reproduction et le régime alimentaire des spécimens spécimens des côtes tunisiennes[END_REF]. Such estimations could not be carried out during this study due to the absence of specific species during certain seasons and the relatively small sample sizes with a limited number of individuals in each maturity stage.

Life history aspects and overexploitation

Cartilaginous fish act as top predators in marine ecosystems [START_REF] Wetherbee | Food consumption and feeding habits[END_REF]. Their chronic overfishing has reduced population sizes, fragmented large populations into small, locally-isolated ones [START_REF] Nadon | Re-Creating Missing Population Baselines for Pacific Reef Sharks Recreación de las Líneas de Base Poblacionales Faltantes para Tiburones de Arrecife en el Pacífico[END_REF], and led to trophic cascades [START_REF] Myers | Cascading Effects of the Loss of Apex Predatory Sharks from a Coastal Ocean[END_REF].

Despite these rapid declines, little is known about their ability to persist in smaller, more fragmented populations and to recover from human-induced bottlenecks [START_REF] Field | Susceptibility of sharks, rays and chimaeras to global extinction[END_REF]. In the Mediterranean, little is known about the overall organization, structure, and complexity of the group/population of sharks. However, in tropical waters some studies display some behavioral aspects of sharks. For example, some females of species like the Sharptooth Lemon Shark, Negaprion acutidens, exhibit behavioral patterns (philopatry) by returning to the same nursery on multiple years to give birth. The latter population also shows patterns of connectivity between the islands in archipelago and dispersal which are used as a strategy to avoid mating with closely related partners (Mourier et al., 2013). Philopatry was also observed in the same region for some females of the Blacktip Reef Shark, Carcharhinus melanopterus, that migrated to the same nursery for every birthing event (Mourier and Planes, 2013).

While life history provides considerable awareness to the response of chondrichthyan populations to exploitation, the incidental catches and direct targeting of elasmobranchs in Lebanon has led to the urge to increase awareness of conservation needs. In addition, the Lebanese production of elasmobranchs was 60 tons in 2003 accounting for 2% of all groups caught [START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF]. No catch assessment surveys were conducted for the past 30 years covering the entire coast, and Lebanon has stopped sending data to FAO since 2006 [START_REF] Pinello | Fishing fleet data for 2011[END_REF]. As claimed previously, the reality that artisanal fishermen face every day is far from the official landing records of elasmobranchs. Therefore, human resources, especially taxonomists, should be encouraged to help data collection or recordings of artisanal fishing operations. This will ameliorate landing statistics through the basic use of scientific names and not generalized names.

In Lebanon, several elasmobranchs are captured, either through directed fishing operations or through bycatch. The results of this thesis show that that Common Guitarfish, Rhinobatos rhinobatos, is the most commonly targeted elasmobranch in the Lebanese longline fisheries, especially in Tripoli. This elasmobranch, considered Endangered by IUCN, also shows an intense exploitation pattern in Iskenderun Bay, northeastern Mediterranean [START_REF] Cicek | Study on the potentially economical important species trawled from Karatas¸ (Adana) Coasts[END_REF][START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF]. Although declared extinct in the northern Mediterranean, it persists in areas of the southern Mediterranean, particularly the Gulf of Gabés [START_REF] Sciara | Rhinobatos rhinobatos[END_REF]; nonetheless, the results of this study confirm its presence in the eastern Mediterranean with a significant commercial value in the northern region of Lebanon. The Gulper Shark, Centrophorus granulosus, however, is more commonly exploited as bycatch. This species presents very conservative life history traits with a long gestation period displaying a Vulnerable IUCN status; thus, its conservation and protection must be facilitated along the Lebanese coast.

Many studies link fish life histories to overexploitation. Exploitation affects life history. Changes to age and size at maturity, longevity, and quite possibly fecundity and egg size are the product of phenotypic and genetic responses to fishing [START_REF] Rochet | Short-term effects of fishing on life history traits of fishes[END_REF][START_REF] Law | Fishing, selection, and phenotypic evolution[END_REF][START_REF] Hutchings | Life histories of fish[END_REF]. An example related to bony fish is the Atlantic cod (Gadus morhua) whose 30-to 40-year declines have been associated with significant reductions in age and length at maturity, changes mostly explained as genetic responses to fishing [START_REF] Hutchings | Life history consequences of overexploitation to population recovery in Northwest Atlantic cod (Gadus morhua)[END_REF]. Cartilaginous fishes are less productive and more vulnerable to extinction than bony fishes due to their life history traits [START_REF] Myers | Extinction, survival or recovery of large predatory fishes[END_REF][START_REF] Simpfendorfer | The importance of research and public opinion to conservation management of sharks and rays: a synthesis[END_REF]. Their low productivity (small litters, slow growth rates, late sexual maturity and long gestation periods) make them incapable to compensate increased mortality rendering them more vulnerable to extinction [START_REF] Macarthur | The equilibrium theory of island biogeography[END_REF]. Many studies also linked life history traits to risk of overexploitation and extinction in cartilaginous fishes [START_REF] Hoenig | Elasmobranchs as living resources: advances in the biology, ecology, systematics, and the status of fisheries[END_REF][START_REF] Kirkwood | Harvesting species of different lifespans[END_REF][START_REF] Cortés | Demographic analysis as an aid in shark stock assessment and management[END_REF][START_REF] Smith | Intrinsic rebound potentials of 26 species of Pacific sharks[END_REF][START_REF] Heppell | Life table analysis of long-lived marine species with implications for conservation and management[END_REF][START_REF] Cortés | Incorporating uncertainty into demographic modeling: Application to shark populations and their conservation[END_REF][START_REF] Gedamke | Using demographic models to determine intrinsic rate of increase and sustainable fishing for elasmobranchs: pitfalls, advances, and applications[END_REF], and considering this group's natural vulnerability and long life spans, conservation measures should be reviewed to avoid local extinctions. Legally and practically limiting the fishing of elasmobranchs is the main measure that should be applied (Increase control on ports and in fisheries, set quotas to limit biomass of elasmobranchs caught, in addition to enforcing MPAs).

Awareness should be also spread among the fishermen community for better understanding of the importance of elasmobranchs as top predators in the marine ecosystem. Accordingly, this thesis presented the life history of two intensely exploited elasmobranchs. Knowing that no official landing records are found for these two species, the results of the thesis provide evidence that can identify the threats posed by artisanal fisheries for the survival of the Gulper Shark and the Common Guitarfish local populations. Moreover, it can be hypothesized that fisheries have certainly already modified life-history traits for the studied populations. For instance, sizes at maturity or mean sizes obtained in the results could be less than those in areas not subject to fishing pressure.

Some life history traits were not studied during the course of this thesis. For instance, timing limits and lack of financial and technical resources obstructed the age estimation of these species. The age estimation can complement growth studies enhancing the reflection of population dynamics. Estimations of age and growth of deep-water chondrichthyans can suggest variable life histories. For instance, such estimations can disclose low turnover rates and also considerable variability in age at maturity and longevity among them [START_REF] Machado | A technique for ageing the birdbeak dogfish (Deania calcea Lowe, 1839) from dorsal spines[END_REF][START_REF] Clarke | Age estimation of the exploited deepwater shark Centrophorus squamosus from the continental slopes of the Rockall Trough and Porcupine Bank[END_REF][START_REF] Sion | A simple technique for aging the velvet belly, Etmopterus spinax (Squalidae)[END_REF][START_REF] Moura | Growth pattern and reproductive strategy of the holocephalan Chimaera monstrosa along the Portuguese continental slope[END_REF][START_REF] Irvine | Surface bands on deepwater squalid dorsal-fin spines: an alternative method for ageing Centroselachus crepidater[END_REF].

In addition, the conventional stomach content analysis was carried out for the Common Guitarfish in order to shed light on the biological aspect of this population. No such analysis was performed for the Gulper Shark because no food was found in all stomachs sampled. This approach in analysis has been criticized for the ‗snapshot' nature of sampling although providing considerable information about the trophic ecology of many animals [START_REF] Pinnegar | Differential fractionation of δ15C and δ15N among fish tissues: implications for the study of trophic interactions[END_REF][START_REF] Pinnegar | Unusual stable isotope fractionation patterns observed for fish hostparasite trophic relationships[END_REF]. It has also been criticized due to the prevalence of unrecognized dietary items [START_REF] Pinnegar | Unusual stable isotope fractionation patterns observed for fish hostparasite trophic relationships[END_REF], bias from regurgitation during capture [START_REF] Renones | Size related dietary shifts of Epinephelus marginatus in a western mediterranean littoral ecosystem: an isotope and stomach content analysis[END_REF], and the difficulty to obtain sufficient sampling frequency to draw significant conclusions [START_REF] Vander Zanden | Comparing trophic position of freshwater fish calculated using stable nitrogen isotope ratios (δ15N) and literature dietary data[END_REF]. In this study, a limited amount of samples containing prey in their stomachs were obtained for Common Guitarfish, and none were obtained for Gulper Sharks. The aim of this approach was to include as many quantitative analyses as possible and it was performed for the Common Guitarfish population only. Nonetheless, such analysis should have been supported by a stable isotope analysis in order to alleviate biases when present. Stableisotope analysis provides estimates of assimilated foods based on measurements of stable isotopes of nitrogen and carbon in tissues of marine consumers [START_REF] Owens | Natural variations in 15N in the marine environment[END_REF][START_REF] Fry | δ13C Measurements as Indicators of Carbon Flow in Marine and Freshwater Ecosystems[END_REF] up to several months back depending on the tissue analyzed. Accordingly, [START_REF] Cortes | Standardized diet compositions and trophic levels of sharks[END_REF] recommended that more attention be focused on the stable isotope approach at least as a validation of conventional dietary analyses.

The use of isotopic ratios of carbon and nitrogen measured in the tissues of consumers as ecological tracers is mainly based on the fact that: 1) The different primary producers of an ecosystem have different isotopic compositions. These are due to the different fixed nutrients that have different isotopic compositions, the different carbon and nitrogen sources used, and/or the biochemical cycle that these primary producers use for photosynthesis [START_REF] Peterson | Stable isotopes in ecosystem studies[END_REF][START_REF] Gannes | Natural abundance variations in stable isotopes and their potential uses in animal physiological ecology[END_REF].

2) The enrichment in 13 C and 15 N between a source (prey) and its consumer is relatively predictable for omnivorous consumers and/or carnivores (TEF for "Trophic Enrichment Factor"). It is less important for 13 C (1 ‰) than 15 N (3.4 ‰ on average) [START_REF] Post | Using stable isotopes to estimate trophic position: models, methods and assumptions[END_REF]. This TEF may be lower but also more variable in herbivorous consumers and can be used to calculate δ 13 C and δ 15 N. Consumer δ 13 C values are generally used as tracers of their feeding or habitat zone, as their isotopic composition is similar to that of primary producers in the food web to which they belong [START_REF] France | Carbon-13 enrichment in benthic compared to planktonic algae: food web implications[END_REF][START_REF] Hobson | Tracing origins and migration of wildlife using stable isotopes: a review[END_REF]. Values of δ 15 N are more used as indicators of the trophic position of organisms in their food chain and largely used to calculate the absolute trophic level species in many ecosystems [START_REF] Hobson | Determination of trophic relationships within a high Arctic marine food web using δ13C and δ15N analysis[END_REF][START_REF] Lesage | Marine mammals and the community structure of the Estuary and Gulf of St Lawrence, Canada: evidence from stable isotope analysis[END_REF][START_REF] Loc'h | Benthic community and food web structure on the continental shelf of the Bay of Biscay (North Eastern Atlantic) revealed by stable isotopes analysis[END_REF] (Figure 45).

Figure 45: A schematic diagram of the use of stable isotopes of carbon and nitrogen in the marine environment [START_REF] Chouvelon | Structure et fonctionnement des réseaux trophiques par l'utilisation de traceurs écologiques (isotopes stables, métaux) en environnement marin ouvert : le cas du Golfe de Gascogne[END_REF] This study only included stomach content analysis because it is simpler, requires less resources and is less time-consuming owing that this thesis included several study aspects other than dietary analyses. Moreover, no potential prey sampling was performed because most Common Guitarfish were collected from the commercial fishery in Tripoli. Therefore, no data of prey isotopic composition was found.

Sexes and maturity stages were determined macroscopically. Some authors use only macroscopic features to determine the periods of vitellogenesis, gestation and parturition [START_REF] Abdel-Aziz | Reproductive cycle of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Alexandria waters, Mediterranean Sea[END_REF][START_REF] Megalofonou | Sexual maturity and feeding of the gulper shark, Centrophorus granulosus, from the eastern Mediterranean Sea[END_REF][START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF]. However, without examining testes and ovaries under light microscopy, such determination remains doubtful. Research by [START_REF] Maruska | Periodic gonadal activity and protracted mating in elasmobranch fishes[END_REF] on batoids demonstrated that the gonado-somatic index and macroscopic observation of the gonads are insufficient measures of reproductive activity. The internal structure of the testis and ovaries each maturity stage should described histologically to verify the macroscopic maturity scale and to allow for a better understanding of reproduction in term of maturity acquisition and reproductive cycle. A lot of aspects other than reproductive histology were performed during the course of this study. Lack of time and sufficient funding prevented such additional biological measures during this thesis.

General situation and recommendations

The Lebanese fishing fleet is composed of small scale artisanal vessels less than 12 m in length and typical of many Mediterranean countries [START_REF] Brême | Analyse situationnelle de la Pêche côtière[END_REF][START_REF] Majdalani | The present status of fishery and information system in Lebanon[END_REF][START_REF] Carpentieri | Socio-economic development of the community of the fishermen of Tyre‖ Preliminary analysis of the fishing sector of Tyre (south Lebanon)[END_REF][START_REF] Majdalani | Census of Lebanese Fishing Vessels and Fishing Facilities[END_REF][START_REF] Lelli | Commercial landing and fishing metiers within the artisanal fishery of Tyre, Lebanon. Socio-economic development of the fishing Community of Tyre, Lebanon' promoted by the Italian NGO ‗Ricerca e Cooperazione' in collaboration with Caritas Lebanon and co[END_REF][START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF]PescaMed, 2011;[START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF]. All the effort of the fleet is concentrated within the 6 nautical miles with higher percentage within the 3 nautical miles leading to a high fishing pressure on the coastal fisheries resources [START_REF] Bariche | Structure and biological characteristics of purse seine landings off the Lebanese coast (eastern Mediterranean)[END_REF][START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF][START_REF] Colloca | Report of the FAO EastMed support to the fishing trials carried out off the South Lebanese Coast[END_REF]). An estimated 4,850 tons with a value of 26.98 Million USD was landed by all fleet in 2011 (Figure 46). The average price per kilogram of the production in Lebanon was $5.6 which is relatively high compared to the European prices ($6.1). The most important channel for the sale of production is the auction market [START_REF] Pinello | Fishing fleet data for 2011[END_REF].

Formal stock assessments have not been carried out in Lebanon. Fishing practices target juvenile fishes because the market favors the smallest fishes, which are consumed whole and without gutting far [START_REF] Bariche | Structure and biological characteristics of purse seine landings off the Lebanese coast (eastern Mediterranean)[END_REF][START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF]. The small pelagic fishery constitutes two thirds of the Lebanese landings. This fishery is based on 4 main species including Engraulis encrasicolus, Sardina pilchardus, Sardinella aurita and Scomber japonicus [START_REF] Pinello | Fishing fleet data for 2011[END_REF]. Fishing does not take place beyond the 6 nautical miles; therefore, the fish stocks beyond that can be considered as virgin stocks although their status is not known. Indeed, it is illegal in Lebanon to fish beyond the 6 nautical mile limit, and this is heavily controlled by the Lebanese army and the fishing vessels are not equipped to fish beyond that distance from the coast [START_REF] Sacchi | Report of the FAO EastMed assessment of the fishing gears in Lebanon[END_REF].

A recent study was conducted in order to have a preliminary idea of situation of stocks beyond the 6 nautical miles. [START_REF] Colloca | Report of the FAO EastMed support to the fishing trials carried out off the South Lebanese Coast[END_REF] assessed the potentiality of offshore fishing grounds for local artisanal fishery and conducted a short survey in the area between Tyre and Naqoura in the south, using both monofilament gillnets to target hake (Merluccius merluccius)

and Spanish traps designed to catch the striped soldier shrimp (Plesionika edwardsii). Hake was the most abundant species in the catch with CPUE up to 6.6 kg/km net day in the offshore sampling stations. The traps for the soldier shrimps gave mean CPUEs of 210-310 g/trap/day, which is higher than those obtained in other parts of the Mediterranean.

No stock assessment or recordings related to chondrichthyan landings have been conducted

along the Lebanese coast. Although the majority of fishermen target bony fish, some target elasmobranchs and others land most of their elasmobranch bycatch. No official data is present regarding the precise number of elasmobranchs landed along the Lebanese coast, although 60 tons of elasmobranch landings were recorded in 2003 [START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF]. We can hypothesize that the main chondrichthyan bycatch occurs with the minor gear of 6 to 12 m because they are the most operational in Lebanon [START_REF] Majdalani | Census of Lebanese Fishing Vessels and Fishing Facilities[END_REF].

Furthermore, according to our observations, elasmobranchs are landed and sold in certain regions along the coast, such as Tripoli in the north. Some are observed in fisheries in Sidon, however, not in Tyre, although both mentioned regions are present in the south. It can be inferred that the presence of elasmobranchs in fisheries can be attributed to the society and requirements in each region along the coast. Moreover, the data collected from fisheries is sufficient to agree that management measures should be implemented to limit the capture of elasmobranchs and prohibit the exploitation of those that are threatened according to IUCN.

Consequently, following the present study that reflected the situation of elasmobranchs along the Lebanese coast, certain actions should be taken to induce the conservation and sustainable management of this fish class. It is recommended that research programs on systematics, life history and population dynamics should be carried out in a manner harmless for species of concern (for instance, tagging or use of ‗Remotely Operated Underwater vehicule' (ROV).

Moreover, critical habitats should be identified and mapped in order to issue laws preventing the capture of chondrichthyans in such areas. The Lebanese Ministry of Agriculture must take action to collect reliable statistics on the landings and bycatch of elasmobranchs to facilitate their future sustainable management. Action plans and research programs must be developed in order to reduce elasmobranch bycatch and initiate fisheries management strategies for commercially exploited species. Bycatches can be limited by targeted spatio-temporal fisheries closures [START_REF] Dunn | Spatio-temporal management of fisheries to reduce bycatch and increase fishing selectivity[END_REF], banning total effort and limiting the level of effort, and setting limits on permissible levels of bycatch [START_REF] Hall | On bycatches[END_REF]. [START_REF] Hall | On bycatches[END_REF] reviewed several mitigation measures specific for the management of bycatch. For instance, the latter presented five possible lines of defense available to reduce bycatches: (1) increasing the selectivity of the fishery by choices of gear, areas, or seasons; (2) modifying deployment conditions; (3) increasing the fraction released alive either from the gear, or (4) later, from the deck; or (5) increasing the utilization to make catches out of the incidental captures.

Conclusion and perspectives

The current study has confirmed the presence of cartilaginous fish species and demonstrated their diversity, although still poorly known. This thesis has collected new information on the fundamental biology of two exploited cartilaginous fishes along the Lebanese coast, allowing for a better understanding of their general ecology particularly to implement decrees specific for their sustainable management and conservation. This study has also shed light to the lack in studies, especially in genetics, distribution, and stock assessment of this fish class in the Eastern Mediterranean. The majority of studies are focused on the life history characteristics of the species' biological cycle, growth, reproduction and nutrition. This thesis confirmed that these fish are caught along the Lebanese coast, where some are sold and others discarded dead at sea.

It also reflected the dangers faced by two exploited species (C. granulosus and R.rhinobatos) that are considered threatened according to IUCN. Accordingly, it is recommended that actions should be implemented to enforce the sustainable management, protection and conservation of chondrichthyans inhabiting the Lebanese coastal waters. It is evident that management and conservation actions will not be accomplished efficiently due to social issues related to the fishermen community. The latter rely on natural fisheries resources for their economic independence and might hinder several conservation action plans. Therefore, such reality must not restrain researchers from providing basic and applied science.

Perspectives about life history traits and fisheries

Following this study, it can be interesting to initiate age determination research. Age determination studies have been carried out in several areas of the Mediterranean and have at term succeeded in describing some life history aspects of certain populations. Age estimations can be performed using vertebrae for some species, such as Rhinobatos rhinobatos [START_REF] Ismen | Age, growth, reproductive biology and food of the common guitarfish (Rhinobatos rhinobatos Linnaeus, 1758) in İskenderun Bay, the eastern Mediterranean Sea[END_REF][START_REF] Basusta | Age and growth of the common guitarfish, Rhinobatos rhinobatos (Linnaeus, 1758), in Iskenderun Bay (northeastern Mediterranean,Turkey)[END_REF], Torpedo marmorata [START_REF] Duman | Age and growth characteristics of marbled electric ray Torpedo marmorata (Risso, 1810) inhabiting Iskenderun Bay, north-eastern Mediterranean Sea[END_REF], Dasyatis pastinaca [START_REF] Ismen | Age, growth, reproduction and food of common stingray (Dasyatis pastinaca L., 1758) in İskenderun Bay, the eastern Mediterranean[END_REF], and Raja radula [START_REF] Yigin | Age, growth and reproduction of the rough ray, Raja radula (Delaroche, 1809) in Saros Bay (North Aegean Sea)[END_REF] or spines for others, such as Squalus acanthias [START_REF] Avsar | Age, growth, reproduction and feeding of the spurdog (Squalus acanthias Linnaeus, 1758) in the South-eastern Black Sea[END_REF][START_REF] Bubley | Reassessment of spiny dogfish Squalus acanthias age and growth using vertebrae and dorsal-fin spines[END_REF]. Estimating age allows the calculation of the growth rate, mortality rate and productivity, making it one of the most influential variables for estimating a population's status and assessing the risks associated with overfishing [START_REF] Cailliet | Age determination and validation in chondrichthyan fishes[END_REF][START_REF] Goldman | Species accounts: Alopias vulpinus. In Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes[END_REF]. Unfortunately, this life history characteristic is lacking for most cartilaginous species within the eastern Mediterranean Sea, and absent in our study area;

therefore, studies dealing with this topic are indispensable. In this context, dorsal spines of the Gulper Shark collected specimens were preserved in alcohol for further age determination studies using spines.

Moreover, a perspective should address the internal structure of the testis and ovaries each maturity stage histologically to verify the macroscopic maturity scale and to allow for a better understanding of reproduction in term of maturity acquisition and reproductive cycle.

In this study, parasitism was not observed; however, some studying link parasitism to certain life history traits; for instance, the effect cause by parasites on reproductive organs of deep-sea squaloid sharks [START_REF] Yano | The Effect of the Mesoparasitic Barnacle Anelasma on the Development of Reproductive Organs of Deep-sea Squaloid Sharks, Centroscyllium and Etmopterus[END_REF] or in gill filaments causing energy losses [START_REF] Benz | Disease caused by Nemesis robusta (van Beneden, 1851) (Eudactylinidae: Siphonostomatoida: Copepoda) infections on gill filaments of thresher sharks (Alopias vulpinus (Bonnaterre, 1758)), with notes on parasite ecology and life history[END_REF].

Due to the absence of market follow-ups concerning the process of marketed elasmobranchs, it can be efficient to organize a study dealing with the economic impact of cartilaginous fish production in Lebanese fisheries. Such a topic might display the social demand for elasmobranch meat and summarize the vague social benefits of these fish in Lebanon. This can also aid in regulating the catches and exploitation of these fish, particularly those showing a threatened status.

New study tools

In addition, an important perspective of this study will be to validate and complement the cartilaginous fish diversity, distribution and abundance results by using harmless alternative data collection methods. For instance, the usage of a ‗Remotely Operated Underwater Vehicle' (ROV) to scan areas, where cartilaginous fish are claimed to be abundant, will be an effective approach. This alternative method will allow to take photographs or videos of live chondrichthyans in their habitat. Moreover, elasmobranch tagging programs can be carried out in this context, if available funds and means are present. Valuable information on a wide variety of aspects of elasmobranch biology, including life history parameters, stock status, behavioral and distribution patterns, and migration patterns can be provided by tagging studies. The ability to note the presence of a particular fish or group of fish in time and space by marking provides a significant tool to the fishery managers [START_REF] Rounsefell | Fishery scienceits methods and applications[END_REF] and may be the most cost-effective, reliable, and direct means to collect data for studying populations [START_REF] Everhart | Principles of fishery science[END_REF][START_REF] Gordon | Fish marking and the Magnuson Act[END_REF]. Tags are made of various materials, are sometimes designed for specific species or groups of animals, and have been used with varied success. The most common physical tag is external, with some form of anchor that penetrates the skin or other tissues, and includes a component for recognition of individuals [START_REF] Bergman | Perspectives on design, use, and misuse of fish tags[END_REF].

Moreover, [START_REF] Leurs | Risks and advantages of using surface laser photogrammetry on free-ranging marine organisms: a case study on white sharks Carcharodon carcharias[END_REF] evaluated risks and advantages of using surface laser photogrammetry on Great White Sharks suggesting that this method can successfully increase length estimation, accuracy and illustrates the potential utility of this technique for growth and stock assessments on free-ranging marine organisms. In addition, stereo-video photogrammetry was also used to document swimming and non-swimming behaviors of various life-history stages of the Grey Nurse Shark, Carcharias Taurus, in Australia [START_REF] Smith | Behaviour of aggregated grey nurse sharks Carcharias taurus off eastern Australia: similarities and differences among life-history stages and sites[END_REF].

Perspectives about genetic studies

Furthermore, most studies on elasmobranch population structure have relied on fishery catch data [START_REF] Fitzmaurice | Size distribution and food of thornback rays (Raja clavata L.) caught on rod and line on the Mayo coast[END_REF][START_REF] Aldebert | Demersal resources of the Gulf of Lions (NW Mediterranean). Impact of exploitation of fish diversity[END_REF] or on tagging programs [START_REF] Templeman | Migrations of thorny skate, Raja radiata, tagged in the Newfoundland area[END_REF][START_REF] Little | Common skate and tope: First Results of Glasgow Museum's tagging study[END_REF][START_REF] Duarte | First results of a tagging program on tope shark, Galeorhinus galeus, and thornback ray, Raja clavata, in Azorean waters[END_REF] to determine species distribution, abundance or dispersal potential and to detect demographic fluctuations. Nonetheless, these approaches cannot completely assess population sub-structuring (e.g. definition of stocks) or clarify the phylogenetic relationship among species. In the last two decades, molecular techniques have been used to address these aspects in a wide range of animal populations, including many fish species [START_REF] Rocha-Olivares | High genetic diversity, large inter-oceanic divergence and historical demography of the striped mullet[END_REF][START_REF] Takeyama | Mitochondrial DNA sequence variation within and between tuna Thunnus species and its application to species identification[END_REF]. Molecular genetics have become increasingly important in conservation issues [START_REF] Alves | Mitochondrial DNA variation in the highly endangered cyprinid fish Anaecypris hispanica: Importance for conservation[END_REF]. For example, the difficulty in identifying species involved has made monitoring the trade of shark-derived products [START_REF] Chapman | A streamlined, bi-organelle, multiplex PCR approach to species identification: Application to global conservation and trade monitoring of the great white shark, Carcharodon carcharias[END_REF][START_REF] Abercrombie | Global-scale identification of hammerhead sharks: Application to assessment of the international fin trade and law enforcement[END_REF] and preventing quantitative stock assessments [START_REF] Clarke | Global estimates of shark catches using trade records from commercial markets[END_REF] problematic. However, mixtures of genomic DNAs can be used to discriminate protected species from those that are valid commercial taxa [START_REF] Pank | Rapid and simultaneous identification of body parts from the morphologically similar sharks Carcharhinus obscurus and Carcharhinus plumbeus (Carcharhinidae) using multiplex PCR[END_REF][START_REF] Shivji | Genetic identification of pelagic shark body parts for the conservation and trade monitoring[END_REF][START_REF] Chapman | A streamlined, bi-organelle, multiplex PCR approach to species identification: Application to global conservation and trade monitoring of the great white shark, Carcharodon carcharias[END_REF]. Insights from genetic analyses can be useful for addressing population genetic issues, revealing whether two disjunctive populations share a common gene pool [START_REF] Heist | Population genetics of the sandbar shark (Carcharinus plumbeus) in the Gulf of Mexico and Mid-Atlantic Bight[END_REF] or clarifying taxonomic relationships between species [START_REF] Gardner | Taxonomic affinities within Australian and New Zealand Mustelus sharks (Chondrichthyes: Triaakidae) inferred from allozymes, mitochondrial DNA and precaudal vertebrae counts[END_REF]. In this context, an important perspective dealing with cartilaginous fish genetic studies can be addressed along the Lebanese coast in the future. Such studies will be unique for this region and even among the few in the Mediterranean Sea [START_REF] Hoelzel | Low worldwide genetic diversity in the basking shark (Cetorhinus maximus)[END_REF][START_REF] Moftah | Classification of sharks in the Egyptian Mediterranean waters using morphological and DNA barcoding approaches[END_REF]. These studies might permit the differentiation between populations in the eastern and western part of Mediterranean, possibly displaying any genetic changes any chondrichthyan population might have underwent due to several factors. They might also aid in a proper taxonomic structuring of the chondrichthyan populations inhabiting the Lebanese coastal waters. For instance, dispersal ability and associated traits such as habitat preference and size are major factors affecting the population genetic structure of elasmobranchs [START_REF] Veríssimo | Global population structure of the spiny dogfish Squalus acanthias, a temperate shark with an antitropical distribution[END_REF][START_REF] Karl | Phylogeography and conservation of the bull shark (Carcharhinus leucas) inferred from mitochondrial and microsatellite DNA[END_REF].

Significant intraspecific genetic structuring has been reported for small, regionally restricted species, such as Raja clavata [START_REF] Chevolot | Phylogeography and population structure of thornback rays (Raja clavata L., Rajidae)[END_REF] or Squalus acanthias [START_REF] Veríssimo | Global population structure of the spiny dogfish Squalus acanthias, a temperate shark with an antitropical distribution[END_REF], whereas more subtle population differentiation is evident over at least part of the ranges of larger, highly free-swimming, oceanic fish with global distributions, such as I. oxyrinchus [START_REF] Schrey | Microsatellite analysis of the population structure in the shortfin mako (Isurus oxyrinchus)[END_REF], C. maximus [START_REF] Hoelzel | Low worldwide genetic diversity in the basking shark (Cetorhinus maximus)[END_REF] and R. typus [START_REF] Castro | Population genetic structure of Earth's largest fish, the whale shark (Rhincodon typus)[END_REF][START_REF] Schmidt | Low genetic differentiation across three major ocean populations of the whale shark, Rhincodon typus[END_REF]. Nevertheless, exceptions to this pattern are caused by environmental factors that directly affect the life history characteristics of fishes [START_REF] Hauser | Population identification in pelagic fish: The limits of molecular markers[END_REF].

Moreover, microsatellite analyses of the Blacktip Reef Shark, Carcharhinus melanopterus, was performed by [START_REF] Vignaud | Microsatellite analyses of Blacktip Reef Sharks (Carcharhinus melanopterus) in a fragmented environment show structured clusters[END_REF] in French Polynesia and suggested a fragmented habitat for this species in that region. The result of the latter study added emphasis to the case that total bans on shark fishing are a better conservation approach for sharks than marine protected area networks.

Consequently, this study constitutes a basic cornerstone and opens a wide door for many other complementary ones to come. Cartilaginous fish research should be maintained for better understanding, protection and conservation of this fish class in Lebanon. These top predators have a major role in the marine ecosystem. Their loss affects the balance of the ecosystem, and our role, as scientists, is to maintain their protection by compromising between major social demand for these fish and the balance of Mother Nature.

List of tables and figures

Figure 1: Map of the Mediterranean Sea and surrounding countries [START_REF] Cuttelod | The Mediterranean: A biodiversity hotspot under threat[END_REF]. ........

Objectifs de l'étude

Le commencement de travaux de recherche sur les espèces de poissons cartilagineux le long de la côte libanaise s'avérait être une nécessité. En effet, cette classe de poissons a été progressivement exploitée dans cette région et les décrets du ministère libanais ne sont pas toujours appliqués de manière efficace. En outre, il n'existe presque aucune connaissance écrite reflétant la présence et la répartition des espèces de chondrichtyens le long de la côte libanaise.

Leur présence est souvent documentée et présentée dans diverses régions de la Méditerranée et notamment celle du bassin oriental; néanmoins, des lacunes existent le long de la côte libanaise.

Par conséquent, l'absence de données, l'exploitation et l'absence de gestion de cette catégorie de poisson ont été les moteurs de base de cette étude.

Cette thèse vise à contribuer à une meilleure connaissance des poissons cartilagineux du milieu marin libanais. L'accent a été porté sur les axes suivants: La perte des prédateurs de haut niveau que sont les élasmobranches affecte l'équilibre de l'écosystème et notre rôle en tant que scientifiques est de maintenir leur protection en essayant de trouver un compromis entre la demande sociale majeure pour ces poissons et l'équilibre de Mère Nature.

Abstract

The aim of this study is to contribute to a better knowledge of cartilaginous fish in the Lebanese coastal waters, Eastern Mediterranean. Emphasis was placed on various aspects of the distribution, diversity, biology and ecology of these species. In this study, a total of 314 specimens of cartilaginous fish were sampled. These specimens constituted of 25 cartilaginous fish species, 11 shark species and 14 batoid species. No chimaeras were recorded. The data was collected from two sources: (a) an experimental survey in the framework of the CIHEAM PESCA-Libano project and (b) periodic observation of fisheries and catches of hired fishermen. Spatio-temporal distribution was evaluated using the Catch Per Unit Effort of the experimental survey data. Spatio-temporal diversity was also estimated taking into account the total number of species caught in the survey and fisheries/fishermen data. Length-weight relationships for three sharks and five batoids were also presented for species of the combined data sources having more than 10 individuals. Finally, the biology and ecology of two commercially significant and exploited species were also presented as a first step in their fishery management and conservation.

Keywords

  espèces de requins et 14 espèces de batoïdes. Aucune chimère n'a été enregistrée. Les requins échantillonnés étaient constitués majoritairement des espèces: Centrophorus granulosus, Galeus melastomus, Squalus blainville et Mustelus mustelus. La majorité des batoïdes était constituée de Rhinobatos rhinobatos, Rhinobatos cemiculus, Torpedo marmorata, Torpedo nobiliana, Raja miraletus et Raja clavata. Les différents spécimens de poissons cartilagineux ont été pêchés à des profondeurs allant de 10 à 600 m, en majorité à l'aide de palangres, suivis des trémails puis des filets maillants. La Capture par Unité d'Effort a été employée en tant qu'indice d'abondance et ses variations spatiales et saisonnières ont été analysées. La diversité spatio-temporelle a aussi été estimée et les plus fortes valeurs ont été observées dans la région du sud et durant le printemps et l'hiver. Dans une seconde partie, différentes relations longueur-poids ont été établies pour les espèces majoritaires présentant un nombre d'individus supérieur à 10 (3 requins et 5 batoïdes). Enfin, un focus a été porté sur la biologie et l'écologie de deux espèces commercialement importantes et bien exploitées dans les eaux côtières libanaises. La biologie des populations du batoïde Rhinobatos rhinobatos (chapitre V) et du requin Centrophorus granulosus (chapitre VI) a été évaluée séparément à partir d'individus issus des deux sources de données combinées (scientifiques et commerciales). Pour finir, le dernier chapitre (chapitre VII) est consacré à la discussion générale et aux perspectives de cette étude. Mots clés: Chondrichthyens; conservation; distribution; traits d'histoire de vie; Liban;

Figure 3 :

 3 Figure 3: FAO Fishing Area 37: The borders of its subareas and divisions.

Figure 4 :

 4 Figure 4: The worldwide representation of the Elasmobranchii species richness (AquaMaps, 2013).

Figure 6 :

 6 Figure 6: The temporal pattern of chondrichthyan fisheries catch landings. (A) The landed catch of chondrichthyans reported to the Food and Agriculture Organization of the United Nations from 1950 to 2009 up to the peak in 2003 (black) and subsequent decline (red). (B) The rising contribution of rays to the taxonomically-differentiated global reported landed catch: shark landings (light gray), ray landings (black), log ratio [rays/sharks], (red) (FAO, 2011; Dulvy et al., 2014).

Figure 8 :

 8 Figure 8: A Shortfin Mako, Isurus oxyrinchus, caught as bycatch in Lebanon, Levantine Basin of the Mediterranean Sea.



  Convention on the Conservation of European Wildlife and Natural Habitats, Bern 1979 Convention on Migratory Species, Bonn, November 1983 Protocol for Specially Protected Areas and Biological Diversity in the Mediterranean (SPA-BD), the Barcelona Convention, June 1995  United Nations Food and Agriculture Organisation, International Plan of Action for the Conservation and Management of Sharks, 1999 (FAO/IPOA-Sharks)  Convention on International Trade in Endangered Species (CITES) November 2002  United Nations Environment Programme, Mediterranean Action Plan for the Conservation of Cartilaginous Fishes, November 2003

  is composed of small scale artisanal vessels. Trawlers are legally forbidden. According to[START_REF] Martin | Brief introduction to the Eastern Mediterranean fisheries sector[END_REF], the Lebanese production of elasmobranchs was 60 tons in 2003 accounting for 2% of all groups caught. Some elasmobranch catches are incidental and others target certain commercially important species such as the Common Guitarfish Rhinobatos rhinobatos (Linnaeus, 1758) and the Gulper Shark Centrophorus granulosus (Bloch and Schneider, 1801) (Figure9).

Figure 9 :

 9 Figure 9: Gulper Shark (a) and Common Guitarfish (b) catches in fisheries along the Lebanese coast.

  (a) the CIHEAM PESCA-Libano scientific survey carried out with the involvement of the Ministry of Agriculture and the National Center for Marine Sciences -Lebanese National Council for Scientific Research (CNRSL) and (b) fishery and fishermen catch data. In this section, the Catch Per Unit Effort (CPUE) was used to present the spatio-temporal distribution of these species, and several biodiversity indices were calculated to present their spatio-temporal biodiversity. This chapter also consists of a short communication presenting the length-weight relationships of three sharks and five batoids collected through the course of this study.

Figure 10 :

 10 Figure 10: Mean monthly variations for 2000-2012 period of Sea Surface Temperature (SST) and Air Temperature (AT) in Lebanese marine waters (eastern Mediterranean) (Abboud Abi Saab et al., 2013).

  The coast is characterized by the presence of a few bays (Bay of Beirut, Bay of Jounieh, Bay of Shekka and Bay of Akkar). Moreover, real cliffs are rare and exceptionally exceed 30 m in height. The Lebanese coast appears almost straight with a slight skew relative to the Palestinian and Syrian coasts. Despite its small area, it is very fertile and considered as the richest region. It has been occupied by urban civilizations since the original -Phoenician‖ civilization. Nowadays, it is threatened by urban extension as it brings together the main cities. To face some of this threat, two coastal nature reserves/marine protected areas were created by national decrees. Lebanese Ministry of Environment-IUCN (2012), two marine protected areas are present in Lebanon: the -Palm Islands Nature Reserve‖ (Decree 121, 09/03/1992) in the north and the -Tyre Coast Nature Reserve‖ (Decree 708, 05/11/1998) in the south.Palm Islands Nature Reserve (PINR)The PINR is 5.5 km far from the coast of Tripoli. It is formed of 3 islands: Sanani (0.04 km²), Ramkine (0.016 km²) and Palms (0.2 km²). Its area (including 500 m of sea around the islands) is nearly 4.2 km². They are hot stopovers used by sea-crossing migratory birds and the only sites in Lebanon for sea bird breeding. They also comprise a habitat of plants that is no longer found on the eastern Mediterranean littoral, including threatened and endemic species, and important sites for threatened marine turtles and endangered and globally threatened bird species. This reserve, thus, constitutes in general an important area for marine diversity and habitats. These islands are only open to visitors from July to September. Rangers are always present during the visitation season (July-September) to protect, survey and control visitors and poachers. Recently, the reserve's rangers were empowered to issue fines to a poacher or anyone breaking the law. Management plans were prepared by the Ministry of the Environment (MoE) in Lebanon through the consultation of experts from various organizations, such as, IUCN, in order to manage the marine and terrestrial parts of the reserve (Lebanese Ministry of Environment-IUCN, 2012).

  show a very narrow continental shelf (3 -4 km) up till the 200 m isobaths situated 8 to 10 km south and 20 km north. The mean depth of the continental shelf is 20 to 40 m (Goedicke, 1972), and the slope is parallel to the coast, of 1100 to 1400 m depth, and at a distance of 25 to 30 km from the coast before reaching the abyssal plain. The most recent update of bathymetry along the Lebanese coast was performed in fall of 2003 by the Shalimar marine survey. This survey was carried out as part of a French-Lebanese collaborative program to study recent deformation along the Lebanese margin of the Levantine basin. The main objectives were to study the deformation of recent sedimentary layers, map potentially active faults on the seafloor, and identify possible seismic ruptures.

Figure 11 :

 11 Figure 11: Bathymetric mapping of the Lebanese coast at depths greater than 200 m by the Shalimar cruise in 2003[START_REF] Carton | Seismic evidence for Neogene and active shortening offshore of Lebanon (Shalimar cruise)[END_REF].

Figure 12 :

 12 Figure 12: The location of the capital Beirut, the 7 major ports, and the two extreme points along the coast of Lebanon.

  Data collection was aided by the CIHEAM PESCA-Libano project. The CIHEAM PESCA Libano project with the involvement of the Ministry of Agriculture and the National Center for Marine Sciences -Lebanese National Council for Scientific Research (CNRSL) assessed the potentiality of the marine coastal resources in order to support the Lebanese Government in strengthening the management of the marine resources. A survey in the framework of this project was done in 2012 and 2013, where three types of gears were lowered in 62 different sites along the coast of Lebanon and at depths ranging from 10 to 600 m (Figure 13).

Figure 13 :

 13 Figure 13: The hauls of the CIHEAM PESCA-Libano survey along with the gear used at each haul.

Figure 14 :

 14 Figure 14: A photograph of the claspers in a male Centrophorus granulosus (a) and their absence in a female individual (b) of the same species.

Figure 18 :

 18 Figure 18:The boundary of the Eastern Mediterranean subarea (37.3) -Aegean (Division 37.3.1) and Levant (Division 37.3.2)along with the Western and Central basins as adapted from the United Nations Food and Agriculture Organization (FAO, 2004).

  who cataloged 22 cartilaginous species along the Lebanese coast by field work performed between 1973 and 1983; and later Harmelin-Vivien et al. (2005) mentioned the presence of three species in an underwater visual census survey along the Lebanese coast in 2001.

  established.During 1954[START_REF] Ben-Tuvia | Two Indo-Pacific Fishes, Dasyatis uarnak and Upeneus moluccensis, in the Eastern Mediterranean[END_REF] reported the observation of several specimens of the Red Sea migrant, Himantura uarnak, along the coast of Israel. Later,[START_REF] Ben-Tuvia | Report on the fisheries research in the Bardawil Lagoon for the years 1975-1976[END_REF]reported large catches of two shark species Carcharhinus plumbeus (Nardo, 1827) and Carcharhinus obscurus (Lesueur, 1818) outside the openings connecting the Bardawil Lagoon (northern Sinai) to the Mediterranean between 1975 and 1976. Studies on cartilaginous fish observations were then maintained along the coast of Israel, where[START_REF] Golani | On deep-water sharks caught off the Mediterranean coast of Israel[END_REF] recorded the first occurrence of Somniosus rostratus (Risso, 1827), authenticated the presence of Centrophorus granulosus and Dalatias licha (Bonnaterre, 1788)in the region, and noted Galeus melastomus(Rafinesque, 1810)

  1829) was caught in a trawl in May 1997 in Iskenderun Bay at about 120-200 m depth and recorded for the first time in the eastern Mediterranean coast of Turkey[START_REF] Basusta | Occurrence of a Sawback Angelshark (Squatina aculeata Cuvier, 1829) off the Eastern Mediterranean Coast of Turkey[END_REF]. Again in Iskenderun Bay (Eastern Mediterranean), two gravid Lusitanian Cownose Rays, Rhinoptera marginata (Geoffroy Saint-Hilaire, 1817) were captured by a bottom trawl for the first time and documented byBasusta et al. (2012b). Furthermore, the occurrence of Dasyatis marmorata(Steindachner, 1892) in Turkey was confirmed in[START_REF] Kapiris | New Mediterranean Biodiversity Records[END_REF] from samples collected between 2005 and 2011 off Iskenderun Bay, Adana, and Mersin (Levantine basin). The latter species was first mentioned by Diamant et al. (2010) as D. chrysonota in the northeastern Levant without providing any taxonomical information. According to Bradai et al. (2012), all previous records given from the Mediterranean Sea under the names D. pastinaca marmorata and D. chrysonota should be considered as D. marmorata, and DNA studies are required to resolve the taxonomical argument. Moreover, the Starry Smooth-hound Mustelus asterias (Cloquet, 1819 )

  analyzed trace metals in the muscle and other organs from several species of deep-water sharks (particularly Centrophorus granulosus and Galeus melastomus) in the Eastern Mediterranean between 1985 and 1991. The latter study revealed a significant correlation between specimen size and the mercury concentration in the muscle as well as in the liver and kidneys, and the overall trace metal content was considerably higher in the specimens from the Eastern Mediterranean compared with the same species from the northeastern Atlantic. More recently,[START_REF] Kousteni | Total mercury concentrations in edible tissues of two elasmobranch species from Crete (eastern Mediterranean Sea)[END_REF] studied the total mercury concentrations in edible tissues of Squalus acanthias and Mustelus mustelus collected around the island of Crete, Eastern Mediterranean. This study revealed that in all muscle samples of M.

  la seule évaluation des ressources, de la distribution et de la diversité des élasmobranches le long de la côte libanaise, en Méditerranée orientale. Les données concernant les poissons cartilagineux sont issues de captures obtenues à partir de deux méthodes de collecte de données complémentaires, issues : (a) du projet scientifique CIHEAM PESCA-Libano réalisé avec la participation du Ministère de l'Agriculture et le Centre national pour les sciences marines -Conseil national libanais pour la recherche scientifique (CNRSL) et (b) des poissonneries et des pêcheurs. Au cours du suivi scientifique, des filets maillants expérimentaux, trémails et palangres ont été déployés à des profondeurs allant jusqu'à 600 m en 2013. Les poissons cartilagineux issus des données commerciales ont été recueillis auprès des principales poissonneries, qui ont été visitées périodiquement le long de la côte libanaise et de captures issues de pêches expérimentales réalisées avec des pêcheurs pendant la même année. La capture par unité d'effort (CPUE) a été utilisée comme un indice de l'abondance des élasmobranches capturés et a montré des variations saisonnières et spatiales de distribution et selon la profondeur.L'utilisation de données scientifiques et commerciales de manière complémentaire a permis de constituer une image plus précise de l'effet de la pêche sur les espèces d'élasmobranches. La diversité spatio-temporelle a également été évaluée et a montré des valeurs plus élevées dans la région sud de la côte et pendant les saisons du printemps et de l'hiver. Cette étude peut servir de base pour évaluer les menaces des opérations de pêche et constituer une base de réflexion pour la mise en place de mesures de conservation possibles pour les espèces de poissons cartilagineux le long de la côte libanaise en vue d'une gestion plus durable des ressources.

  Lebanon is located in the central part of the Levantine basin, Eastern Mediterranean. The coast is affected by a marked deterioration in the coastal water quality, ecological sites and natural resources due to the influence of competing interests. Urbanization due to demographic change has greatly amplified the demand for coastal resources. Climate change and human impact along the Lebanese coast are leading to the rapid alteration of the local biodiversity. Rare are the protection measures for species or ecosystems, and the increase in Indo-Pacific species is increasing the competition with native marine flora and fauna (MoE/UNDP/ECODIT, 2011).

  CIHEAM PESCA-Libano project with the involvement of the Ministry of Agriculture and the National Center for Marine Sciences -Lebanese National Council for Scientific Research (CNRSL) assessed the potentiality of the marine coastal resources in order to support the Lebanese Government in strengthening the management of the marine resources. A survey in the framework of this project was performed from January to August 2013, where hauls have been surveyed by means of experimental gillnets, trammel nets and long liners lowered up to 600 m depth. The project aimed to assess the distribution and abundance of fisheries resources along the Lebanese coasts in order to deliver scientific advice to Ministry of Agriculture for an enhanced fisheries management.

Figure 19 :

 19 Figure 19: Location of the 62 hauls of the PESCA Libano survey in the north, central and south regions of the Lebanese coast according to the Lebanese administrative divisions.

  of species is constrained by their relationships to environmental variables. A CCA was performed on the matrix of CPUE in kilograms and number separately of the different cartilaginous species caught according to the scientific survey factors (gear, region, depth, and season). Concerning the fisheries and fishermen data, another CCA was performed on the total weight of the different cartilaginous species caught according to several factors (gear, region, depth, season, sex, and sexual maturity). The data (CPUE in kilograms and number or total weight) were log transformed before the analyses into log(x+1) in order to homogenize the variances and normalize the distributions. Both CCA analyses were performed using the cca function of the ‗vegan' package on the statistical software ‗R project'(R Development Core Team, 2014) on shark, batoid and combined datasets. The factor modalities were the same as these used for the PERMANOVA analyses.

Figure 20 :

 20 Figure 20: Interpolation maps using the IDW method for the (a) CPUE (expressed in kilograms), (b) CPUE (expressed in number), and (c) specific richness for the combined (left), shark (center), and batoid (right) data sets of the CIHEAM PESCA-Libano survey.

Figure 3 .

 3 Figure 3. Regarding the survey data CCA, sharks showed clear opposition along the two components according to several environmental factors following CPUE (expressed in kilograms and number). Batoids also showed such opposition following both CPUE, especially P. violacea and D. oxyrinchus that showed a close relationship with the highest depth stratum and an opposition to other depth strata. R. rhinobatos also showed clear opposition along the second component to several factors on the positive side of the axis (Figure 21a, b). Regarding the fishery and fishermen data CCA, most sharks showed close relationships to lower depths and the winter season following the total weight. Sex modalities demonstrated clear opposition along the

Figure 21 :

 21 Figure 21: Canonical Correspondence Analysis (CCA) ordination diagrams of species and environmental data following the log transformed CPUE (expressed in kilograms) (a) and CPUE (expressed in number) (b) for survey data, and Total Weight (kg) (c) for fishery and fishermen data for the combined (left), shark (center), and batoid (right) data sets. The shark species are: Ca obs = Carcharhinus obscurus, Ce gra = Centrophorus graulosus, Da lic = Dalatias licha, Ga mel = Galeus melastomus, He gri = Hexanchus griseus, He per = Heptranchias perlo, Is oxy = Isurus oxyrinchus, Mu mus = Mustelus mustelus, Sqbla = Squalus blainville. The batoid species are Da mar = Dasyatis marmorata, Da pas = Dasyatis pastinaca, Da tor = Dasyatis tortonesei, Di oxy = Dipturus oxyrinchus, Gy alt = Gymnura altavela, Pt bov = Pteromylaeus bovinus, Ra cla = Raja clavata, Ra mir = Raja miraletus, Rh cem = Rhinobatos cemiculus, Rh rhi = Rhinobatos rhinobatos, Sqocu = Squatina oculata, Ta gra = Taeniura grabata, To mar = Torpedo marmorata, To nob = Torpedo nobiliana. The environmental data consist of region (HN = North, HC = Central, HS = South), depth (Dpt), season (SsnSPR = Spring, SsnSUM = Summer, SsnAUT = Autumn, SsnWIN = Winter), gear (GrL = Longlines, GrT = Trammel nets, GrG = Gillnets).

  Furthermore, the values of ∆ + , presented in Figure22 (b), fall below the expected average value for the autumn, winter, and summer seasons.

Figure 22 :

 22 Figure 22: Confidence funnel indicating the taxonomic distinctness of the regions (a) and seasons (b) in relation to the pattern for regions and seasons, respectively. The funnel plot shows the 95% probability limits of ∆ + for each value of the number of species. The line indicates average taxonomic distinctness which does not change with S.

  -poids sont présentées pour 8 élasmobranches, 3 requins et 5 batoïdes, dans les eaux marines libanaises, en Méditerranée orientale. Ces élasmobranches ont été collectés à l'aide de palangres, trémails et filets maillants de décembre 2012 à octobre 2014. Des modèles non linéaires ont été employés et les valeurs du paramètre b des relations longueurpoids W = aL b allaient de 1.752 à 3.337. Les relations longueur-poids ne variaient pas selon le sexe, sauf pour le requin Centrophorus granulosus (Bloch & Schneider 1801) et le batoïdes Torpedo marmorata (Risso 1810). Ces relations ne doivent être appliquées que dans les gammes de longueurs observées.

  individuals) of the sampled Common Guitarfish were in the 60 and 70 cm length class. No individuals were observed in the length class of 120 cm. The majority of the females, 33.3% (11 individuals) and 21.2% (seven individuals) occupied the length classes of 60 and 70 cm respectively. In addition, the majority of the males, 32.3% (11 individuals) and 26.5% (nine individuals) occupied the length classes 70 and 60 cm respectively. The length classes of 130 and 140 cm were only occupied by females (Figure 24).Males and females showed significant difference in length distributions, however, no significant differences in weight distributions (for L T : Wilcoxon test, W= 402, P<0.05; for W T : Wilcoxon test, W= 407.5, P>0.05).

Figure 24 :

 24 Figure 24: The length frequency distribution of the Common Guitarfish sample during the study period for males ( ), females ( ) and both sexes ( ).

Figure 25 :

 25 Figure 25: The weightlength relationship of the Common Guitarfish sample during the study 3.3. Sexual maturity and biological indices

Figure 26 :

 26 Figure 26: The number of Common Guitarfish individuals according to the maturity stages and sexes (Males: ; Females: ) (MEDITS, 2012).

Figure 27 :

 27 Figure 27: The proportion of mature Common Guitarfish according to length class to estimate the length at 50% maturity (L 50 ) in logistic regressions (Logistic curves: Males = -----; females = ─────) during the study period for males (•) and females (○).

Figure 28 :

 28 Figure 28: A linear and a nonlinear regression plot showing the relationship between the length of the claspers ((a): L C =0.2304L T -8.375) and the weight of the male gonads ((b): W G = 0.00017 L T2.489 ) and the total length of the individual Common Guitarfish, respectively.

(

   d.f. = 3, P<0.05), whereas no significant differences were observed in the other biological indices during the same period (For I G : Kruskal-Wallis test, Kruskal-Wallis = 1.2335, d.f. = 3, P>0.05; for K: Kruskal-Wallis test, Kruskal-Wallis = 4.7639, d.f. = 3, P>0.05).

Figure 29 :

 29 Figure 29: Boxplots representing the hepato-somatic Index (a), gonado-somatic Index (b), and condition factor (c) of the Common Guitarfish specimens according to seasons (during the study period (black line in box: median; line outside box: general mean between seasons; points in box: mean in each season; points outside box: outliers).

Figure 31 :

 31 Figure 31: The percentage of fullness (F I ) for the full stomachs examined according to total length for the male (a) and female (b) specimens.

Figure 32 :

 32 Figure 32: Feeding strategy graphs of the Common Guitarfish specimens in the autumn (a) and winter (b) seasons.

  capture depths are similar to those of the same species in Iskenderun Bay, Turkey, as recorded by Cek et al. (2009) (depth range: 20 -100 m) and Ismen et al. (2007b) (depth range: 0 -50 m),

  porte sur la biologie et l'écologie de la population du squale chagrin Centrophorus granulosus (Bloch et Schneider 1801) dans les eaux côtières libanaises. Bien que fortement exploitée en tant que prise accessoire, aucune étude n'a été menée sur cette espèce d'élasmobranches dans ce domaine. Un total de 38 individus a été recueilli à partir des eaux marines côtières libanaises au moyen de palangres de fond et de trémails de maillages différents, à des profondeurs allant de 115 à 600 m entre mai 2013 et février 2014. La longueur totale de l'échantillon variait entre 45 et 94 cm avec une moyenne de 80,64 ± 9,97 cm. La majorité des mâles et des femelles occupait des classes de taille dont la longueur allait de 70 cm à 80 cm au total, respectivement. Le poids total des échantillons variait de 870 à 6700 g avec une valeur moyenne de 1312,58 ± 3,791 g. Le sexe-ratio n'était pas significativement différent de 1:1 avec 20 mâles et 18 femelles. Une ségrégation sexuelle bathymétrique a été observée pour cette espèce. La Capture par Unité d'Effort (CPUE) a été utilisée comme un indice d'abondance relative pour détecter la distribution spatiale. La relation longueur-poids, l'indice gonadosomatique, l'indice hépato-somatique, et le facteur de condition des squale chagrins dans la zone d'étude ont également été présentés. Mots-clés: Centrophoridae; poissons cartilagineux; distribution; surexploitation; reproduction; Liban.

A

  total of 38 Gulper Sharks were collected along the coast of Lebanon between May 2013 and February 2014 at depths ranging from 115 to 600 m. Individuals collected came from two sources : firstly, though catches of the major Lebanese fisheries using only long liners (16 collected individuals) and secondly, through the catches of the scientific survey under the PESCA-Libano program that was performed in the framework of the CANA program --Establishing Monitoring and Sustainable Development of the Lebanese Sea‖ -of the Lebanese National Council for Scientific Research (CNRS-L) during the same time period(22 collected individuals). In the latter survey, gillnets and trammel nets (noted T) with different meshes (26 and 30 mm, noted T4 and T6 respectively) along with long liners (noted L) were lowered at different specified hauls with predetermined depths to evaluate the potentiality of the marine coastal resources in order to support the Lebanese Government in strengthening the management of the marine resources. The study area with the major Lebanese ports and the Gulper Shark catches in the PESCA-Libano scientific survey are presented in Figure 33 according to specific coordinates. The exact positions of the fishery catches were not available because the majority of

Figure 33 :

 33 Figure 33: Location of the major ports and of Gulper Shark catches in the PESCA-Libanosurvey along the Lebanese coast (size of the circles is proportional to the number of individuals caught, ‗+' represents the hauls where no Gulper Sharks were caught, and total number of Gulper Sharks caught is in brackets next to the name of the port)

  Finally, a Principal Component Analysis (PCA) was implemented using the FactoMineR package and the PCAmix function of the PCAmixdata package. PCA provides insight into the underlying structure of a large data by synthesizing the relationships between variables. Individuals and variables are projected on principal axes generated by new variables termed principal components, which are linear combinations (LC) of the initial variables. Principal axes and principal components are ordered according to their decreasing contribution to the variance of the data set. Hence, the first axis is the one along which the set of individuals are the most scattered, i.e. they are best discriminated. PCA was implemented on the following numerical variables : L C , W T , L T , L F , L S , W E , I H , W L , I G , W G , K ;and the 4 categorical variables (Season, Haul, Sexual maturity and Depth) where included in the analysis as additional variables with the following modalities : the 8 and 5 modalities of sexual maturity for females and males respectively; 4 modalities of seasons (SPR: spring; SUM: summer; WIN: winter; AUT: autumn); 2 modalities of gears (L: long liners; T:

Figure 34 :

 34 Figure 34: Bar plot representing the number of Gulper Sharks caught by sex (Females: white; Males: black) at various depth classes during the study period by specific gear (T: trammel nets; L: long liners).

Figure 35 :

 35 Figure 35: Spatial distribution of the CPUE kg of the Gulper Shark sample caught in the PESCA-Libano survey using trammel nets of 26 (T4) and 30 mm (T6) meshes and long liners (L) at specific hauls along the Lebanese coast (‗N' is the number of Gulper Sharks caught by the specified gear and the black dots represent all the hauls lowered during the survey and where no Gulper Sharks were caught)

Figure 36 :

 36 Figure 36: Boxplots of the total length (a), total weight (b), and CPUE kg (in kg unit effort -1 in the survey) of the Gulper Shark individuals caught according to the gear used during the study period (black line in box: median; small points outside box: outliers; large points in box: mean for each type of gear; ‗N' is the number of Gulper Sharks in the sample)

Figure 37 :

 37 Figure 37: The length-frequency distribution of the Gulper Shark sample during the study period for both sexes (Males: black; females: white)

Figure 38 :

 38 Figure 38: The length-weight relationships for males (a) and females (b) of the Gulper Shark sample (Black line: complete sample; dotted line: sample without immature individuals)

Figure 39 :

 39 Figure 39: Boxplot representing the gonado-somatic index of the male (a) and female (b) Gulper Shark samples according to the sexual maturity (with 8 maturity stages for females : 1: Immature; 2: Developing; 3a: Capable to reproduce; 3b: Early pregnancy; 3c: Mid pregnancy; 3d: Late pregnancy; 4a: Regressing; 4b: Regenerating; and 5 maturity stages for males : 1: Immature; 2: Developing; 3a: Spawning capable; 3b: Actively spawning; 4: Regressing) during the study period (black line in box: median; points in box: mean for each maturity stage; ‗N' is the number of Gulper Sharks in the sample)

Figure 40 :

 40 Figure 40: The relationships between length of the claspers (a) and weight of the gonads (b) with total length of the male Gulper Sharks

Figure 42 :

 42 Figure 42: The ‗Correlation circle' of the numerical variables (L C : external length of the clasper; W T : total weight, L T : total length, L F : fork length ; L S : standard length ; W E : eviscerated weight, I H : hepato-somatic index ; W L : weight of the liver ; I G : Gonado-somatic index ; W G : weight of the gonads ; K: condition factor) (a) and the ‗Categories' plotof the four categorical variables (Season, Haul, Sexual maturity and Depth) with (Mat: Sexual maturity; SPR: spring; SUM: summer; WIN: winter; AUT: Autumn; L: long liners; T: trammel nets) (b)showing components 1 and 2 of the Principal Component Analysis

Figure 43 :

 43 Figure 43: The proposed marine MPAs along the Lebanese coast (Lebanese Ministry of Environment-IUCN, 2012)

Figure 46 :

 46 Figure 46: Main results of the survey carried out by Pinello and Dimech (2013) regarding fisheries in Lebanon during 2011

Figure 2 :

 2 Figure 2: The current and future threats for marine biodiversity in the Mediterranean (Coll et al., 2010). ..............................................................................................................................................

Figure 3 :

 3 Figure 3: FAO Fishing Area 37: The borders of its subareas and divisions. ..................................

Figure 4 :

 4 Figure 4: The worldwide representation of the Elasmobranchii species richness (AquaMaps, 2013). ..............................................................................................................................................

Figure 5 :

 5 Figure 5: The main shark and ray fishing nations are gray-shaded according to their percent share of the total average annual chondrichthyan landings reported to FAO from 1999 to 2009. The relative share of shark and ray fin trade exports to Hong Kong in 2010 are represented by fin size (Dulvy et al., 2014). ......................................................................................................................

Figure 6 :

 6 Figure 6: The temporal pattern of chondrichthyan fisheries catch landings. (A) The landed catch of chondrichthyans reported to the Food and Agriculture Organization of the United Nations from 1950 to 2009 up to the peak in 2003 (black) and subsequent decline (red). (B) The rising contribution of rays to the taxonomically-differentiated global reported landed catch: shark landings (light gray), ray landings (black), log ratio [rays/sharks], (red) (FAO, 2011; Dulvy et al., 2014). ............................................................................................................................................

Figure 7 :

 7 Figure 7: Spatial patterns of elasmobranchs richness in the Mediterranean Sea (Coll et al., 2010) .......................................................................................................................................................

Figure 8 :

 8 Figure 8: A Shortfin Mako, Isurus oxyrinchus, caught as bycatch in Lebanon, Levantine Basin of the Mediterranean Sea...................................................................................................................

Figure 9 :

 9 Figure 9: Gulper Shark (a) and Common Guitarfish (b) catches in fisheries along the Lebanese coast ..............................................................................................................................................

Figure 10 :

 10 Figure 10: Mean monthly variations for 2000-2012 period of Sea Surface Temperature (SST) and Air Temperature (AT) in Lebanese marine waters (eastern Mediterranean) (Abboud Abi Saab et al., 2013). .........................................................................................................................

Figure 11 :

 11 Figure 11: Bathymetric mapping of the Lebanese coast at depths greater than 200 m by the Shalimar cruise in 2003 (Carton et al., 2009). ..............................................................................

Figure 12 :

 12 Figure 12: The location of the capital Beirut, the 7 major ports, and the two extreme points along the coast of Lebanon. ....................................................................................................................

Figure 13 :

 13 Figure 13: The hauls of the CIHEAM PESCA-Libano survey along with the gear used at each haul. ...............................................................................................................................................

Figure 14 :

 14 Figure 14: A photograph of the claspers in a male Centrophorus granulosus (a) and their absence in a female individual (b) of the same species. .............................................................................

Figure 15 :

 15 Figure 15: A photograph of a dissected Rhinobatos rhinobatos prior to (a) and after (b) liver removal. ........................................................................................................................................

Figure 16 :

 16 Figure 16: The separation, identification and weighing of the prey items found in the stomach of a Rhinobatos rhinobatos specimen. ..............................................................................................

Figure 17 :

 17 Figure 17: The graph of Costello (1990) and its interpretation concerning feeding strategy and prey importance (with O % as the frequency of occurrence and N % as the coefficient of prey numerical abundance). ..................................................................................................................

Figure 18 :

 18 Figure 18:The boundary of the Eastern Mediterranean subarea (37.3) -Aegean (Division 37.3.1) and Levant (Division 37.3.2)along with the Western and Central basins as adapted from the United Nations Food and Agriculture Organization (FAO, 2004). ..............................................

Figure 19 :

 19 Figure 19: Location of the 62 hauls of the PESCA Libano survey in the north, central and south regions of the Lebanese coast according to the Lebanese administrative divisions. ....................

Figure 20 :

 20 Figure 20: Interpolation maps using the IDW method for the (a) CPUE (expressed in kilograms), (b) CPUE (expressed in number), and (c) specific richness for the combined (left), shark (center), and batoid (right) data sets of the CIHEAM PESCA-Libano survey. ........................................

Figure 21 :

 21 Figure 21: Canonical Correspondence Analysis (CCA) ordination diagrams of species and environmental data following the log transformed CPUE (expressed in kilograms) (a) and CPUE (expressed in number) (b) for survey data, and Total Weight (kg) (c) for fishery and fishermen data for the combined (left), shark (center), and batoid (right) data sets. The shark species are: Ca obs = Carcharhinus obscurus, Ce gra = Centrophorus graulosus, Da lic = Dalatias licha, Ga mel = Galeus melastomus, He gri = Hexanchus griseus, He per = Heptranchias perlo, Is oxy = Isurus oxyrinchus, Mu mus = Mustelus mustelus, Sqbla = Squalus blainville. The batoid species are Da mar = Dasyatis marmorata, Da pas = Dasyatis pastinaca, Da tor = Dasyatis tortonesei, Di oxy = Dipturus oxyrinchus, Gy alt = Gymnura altavela, Pt bov = Pteromylaeus bovinus, Ra cla = Raja clavata, Ra mir = Raja miraletus, Rh cem = Rhinobatos cemiculus, Rh rhi = Rhinobatos rhinobatos, Sqocu = Squatina oculata, Ta gra = Taeniura grabata, To mar = Torpedo marmorata, To nob = Torpedo nobiliana. The environmental data consist of region (HN = North, HC = Central, HS = South), depth (Dpt), season (SsnSPR = Spring, SsnSUM = Summer, SsnAUT = Autumn, SsnWIN = Winter), gear (GrL = Longlines, GrT = Trammel nets, GrG = Gillnets).......................................................................................................................................

Figure 22 :

 22 Figure 22: Confidence funnel indicating the taxonomic distinctness of the regions (a) and seasons (b) in relation to the pattern for regions and seasons, respectively. The funnel plot shows the 95% probability limits of ∆ + for each value of the number of species. The line indicates average taxonomic distinctness which does not change with S. .................................................

Figure 23 :

 23 Figure 23: Location of the major ports along the Lebanese coast. .............................................

Figure 24 :

 24 Figure 24: The length frequency distribution of the Common Guitarfish sample during the study period for males ( ), females ( ) and both sexes ( ). ...............................................

Figure 25 :Figure 26 :Figure 27 :Figure 29 :

 25262729 Figure 25: The weightlength relationship of the Common Guitarfish sample during the study ..................................................................................................................................................... 143

Figure 38 :

 38 Figure 38: The length-weight relationships for males (a) and females (b) of the Gulper Shark sample (Black line: complete sample; dotted line: sample without immature individuals) .......

Figure 39 :

 39 Figure 39: Boxplot representing the gonado-somatic index of the male (a) and female (b) Gulper Shark samples according to the sexual maturity(with 8 maturity stages for females : 1: Immature; 2: Developing; 3a: Capable to reproduce; 3b: Early pregnancy; 3c: Mid pregnancy; 3d: Late pregnancy; 4a: Regressing; 4b: Regenerating; and 5 maturity stages for males : 1: Immature; 2: Developing; 3a: Spawning capable; 3b: Actively spawning; 4: Regressing) during the study period (black line in box: median; points in box: mean for each maturity stage; ‗N' is the number of Gulper Sharks in the sample)..................................................................................................

Figure 40 :

 40 Figure 40: The relationships between length of the claspers (a) and weight of the gonads (b) with total length of the male Gulper Sharks .......................................................................................

Figure 41 :

 41 Figure 41: Boxplots representing the hepato-somatic index, gonado-somatic index, and condition factor of the Gulper Shark male individuals (a) and female individuals (b) according to seasons during the study period (black line in box: median; line outside box: general mean between seasons; large points in box: mean in each season; small points outside box: outliers; ‗N' is the number of Gulper Sharks in the sample) ....................................................................................

Figure 42 :

 42 Figure 42: The ‗Correlation circle' of the numerical variables (L C : external length of the clasper; W T : total weight, L T : total length, L F : fork length ; L S : standard length ; W E : eviscerated weight, I H : hepato-somatic index ; W L : weight of the liver ; I G : Gonado-somatic index ; W G : weight of the gonads ; K: condition factor) (a) and the ‗Categories' plotof the four categorical variables (Season, Haul, Sexual maturity and Depth) with (Mat: Sexual maturity; SPR: spring; SUM: summer; WIN: winter; AUT: Autumn; L: long liners; T: trammel nets) (b)showing components and 2 of the Principal Component Analysis ...............................................................................

Figure 43 :

 43 Figure 43: The proposed marine MPAs along the Lebanese coast (Lebanese Ministry of Environment-IUCN, 2012) .........................................................................................................

Figure 44 :

 44 Figure 44: Shark catches reported by developed and developing countries classified by according to the taxonomic levels (FAO, 2014) ..........................................................................................

Figure 45 :

 45 Figure 45: A schematic diagram of the use of stable isotopes of carbon and nitrogen in the marine environment (Chouvelon, 2011) .....................................................................................

Figure 46 :

 46 Figure 46: Main results of the survey carried out by Pinello and Dimech (2013) regarding fisheries in Lebanon during 2011 ...............................................................................................

  25 cartilaginous fish species recorded along the Lebanese coast during this study along with their native distribution according toFishBase (2015). When no detailed information was available for the distribution of the sub regions, the cells were merged. No sub regions were specified for the Pacific and Indian Oceans. ................................................................................. 61 Table 9: The Von Beralanffy growth parameters and age estimation methods for several cartilaginous fish species in different studies in the Eastern Mediterranean (L∞ = the asymptotic or maximum length (or width for some batoids); k = the growth coefficient; and t 0 =the age or time when length theoretically equals zero; M = Males; F = Females; N = Number of specimens; SM = Southeastern Mediterranean; NM = Northeastern Mediterranean; NAS = North Aegean Sea). .............................................................................................................................................. 68 Table 10: The length-weight relationships for cartilaginous fish species in several studies performed in the Eastern Mediterranean (W T : total weight; L T : total length;D W : Disk width; N: number of individuals). ................................................................................................................. 69 Table 11: The stomach content analysis studies and the general results for several cartilaginous fish species in the Eastern Mediterranean (N: The number of specimens)................................... 81 Table 12: The sampling effort represented by the number of hauls where gear (G: gillnets; T: trammel nets; L: longlines) was lowered according to every combination of season, region (N: north; C: central; S: south), and depth strata. ................................................................................ 99 Table 13: List of species (with their total number) caught in the CIHEAM PESCA-Libano survey with CPUE (kg/unit effort) per depth stratum, season and region (N: north; C: central; S: south) of the Lebanese coast. The gear used to catch each species is also represented (T: trammel nets; G: gillnets; L: longlines) along with the International Union for the Conservation of Nature Annex I: Population Structure and Sexual Maturity of the Pufferfish Lagocephalus Sceleratus (Osteichthyes, Tetraodontidae) in the Lebanese and Syrian Marine Waters (Eastern Mediterranean) Gaby Khalaf 1 , Adib Saad 2 , Sherif Jemaa 1 , Waad Sabour 2 , Myriam Lteif 1 and Stefano Lelli 1 1. National Centre for Marine Sciences, CNRS (National Council for Scientific Research), Batroun 534, Lebanon 2. Faculty of Agricultural Engineering, Tishreen University, Lattakieh 1408, Syria Received: March 07, 2014 / Accepted: March 28, 2014 / Published: April 25, 2014. Abstract: The pufferfish Lagocephalus sceleratus is an invasive Lessepsian species of Indo-Pacific origin that has established an increasing population over the past decade in the Levantine basin of the Mediterranean. Besides its toxicity due to the accumulation of tetrodotoxin in its body, it is causing damage to fishing gears and fishermen's catches. This study aims to provide data on the population structure and sexual maturity of this species in the eastern basin of the Mediterranean. A total of 214 individuals were collected in the coastal marine waters of Lebanon and Syria, between January 2012 and June 2013 by means of different types of nets and lines, on soft bottoms, at depths ranging from 10 m to 170 m. The TL (total length) of the samples varies between 10.8 cm and 71 cm. The most common size classes, represented by 125 individuals, are the ones between 30 cm and 50 cm TL, with a bulge at 40 cm, represented by 44 individuals. The average TL is 43.99 cm (standard deviation: SD = 17.65) for both males and females. The TW (total weight) of the specimens ranges between 14 g and 4,603 g with an average value of 1,458.52 g (SD = 1,329.49). The sex ratio (M/F) is 1:1.35 with a total number of 87 males, 118 females and nine unidentified individuals. The length-weight relationship (TW = aTLb) shows a negative allometric growth with b = 2.9481 and R2 = 0.9806. The condition factor (K) is close to one for all samples. The average value of the GSI (gonadosomatic index) shows a substantial increase from winter to spring. The spawning takes place between April and June. Key words: Lagocephalus sceleratus, Lessepsian species, population structure, eastern Mediterranean.Annex II: The classification of the class Chondrichthyes according to[START_REF] Nelson | Fishes of the World[END_REF] Annex IV: List of abbreviations of all parameters along with their units of measurement in the order of their appearance in Chapter 2: Materials and Methods.

1 -

 1 L'établissement d'un inventaire des chondrichtyens le long de la côte libanaise et la réalisation d'une revue bibliographique consacrée aux espèces de poissons cartilagineux en Méditerranée orientale.mars et un maximum de 29.71°C en août, et la variation mensuelle moyenne de la température de l'air a varié entre un minimum de 12.4 °C en janvier et un maximum de 27.59°C en août.Courants et bathymétrie. Un courant général de surface venant de l'océan Atlantique passe par le détroit de Gibraltar dans la Méditerranée. La majeure partie de ce courant se déplace vers l'est parallèlement à la côte nord-africaine, mais perd progressivement de sa force à l'approche des côtes orientales. L'intensité de ce courant et la quantité d'eau atteignant le bassin Levantin dépend de son écoulement à travers le détroit de Gibraltar. Par conséquent, la direction dominante de la circulation générale le long de la côte du Liban est celle du nord durant la plupart de l'année en plus de la présence d'un courant tourbillonnaire de sens général antihoraire en Méditerranée orientale. Ce courant est modifié localement par la configuration de la côte et la topographie de l'étroit plateau continental (3 -4 km). L'isobathe des 200 m est situé à 8-10 km de la côte au sud et à 20 km au nord. La profondeur moyenne du plateau continental est de 20 à 40 m et la pente, parallèle à la côte et située à une distance de 25 à 30 km de cette dernière, s'étend de 1100 à 1400 m de profondeur, avant d'atteindre la plaine abyssale.Secteur de la pêche. La pêche libanaise est artisanale et traditionnelle. La flotte de pêche libanaise est composée de bateaux de pêche artisanaux de moins de 12 m de longueur et typiques de nombreux pays méditerranéens. Elle est composée de 1 460 navires de commerce ayant une licence de pêche. Un nombre total de 42 ports est réparti tout le long de la côte libanaise. La majorité (42%) de la capacité de la flotte est concentrée à Tripoli, dans le nord du pays, tandis que 24% de la flotte totale fonctionne à partir de Beyrouth, au centre du pays et 23% opère dans la partie sud du pays.Les engins les plus couramment utilisés comprennent des trémails, palangres, sennes coulissantes, et lamparos et le chalutage est interdit par la loi, bien que des filets de pêche de maillages illégaux sont largement disponibles sur le marché noir. Seuls quelques navires disposent d'un système de positionnement global (GPS) et seulement 20% des navires sont équipés de petits sondeurs.La production issue des captures au Liban au cours des 10 dernières années a été d'environ 3500 tonnes par an. Cependant, ces données ne reflètent pas l'état actuel et réel de la production halieutique libanaise.Collectedes données. La collecte des données a été réalisée à partir de décembre 2012 jusqu'en octobre 2014, selon trois protocoles différents afin de cibler le maximum d'espèces de poissons cartilagineux le long de la côte libanaise. Le projet CIHEAM PESCA-Libano. Le projet CIHEAM PESCA Libano avec la participation du ministère de l'Agriculture et le Centre national pour les sciences marines -Conseil national libanais pour la recherche scientifique (CNRSL) a évalué le potentiel des ressources côtières marines afin de soutenir le gouvernement libanais dans le renforcement de la gestion des ressources marines. Un échantillonnage a été réalisé dans le cadre de ce projet en 2012 et 2013, durant lequel trois types d'engins (filets maillant, trémail et palangre) ont été déployés dans 61 sites différents le long de la côte du Liban et à des profondeurs allant de 10 à 600 m. Des données sur les poissons cartilagineux ont été recueillies à partir de ce projet et pour chaque station échantillonnée, le type d'engin déployé, les coordonnées et la profondeur étaient notés.Six pêcheurs artisanaux issus de six ports différents ont été embauchés pour déployer les engins à des coordonnées spécifiées. En général, l'équipage incluait 2 à 4 personnes (avec au minimum un scientifique) et un maximum de 2 mises à l'eau d'engin a été effectué par jour, selon les conditions météorologiques et les conditions techniques du navire. Pour chaque trait, la profondeur, le point GPS et les mailles des filets utilisés étaient notés. Aucun appât n'était employé lors du déploiement des filets, mais des appâts ont systématiquement été accrochés aux hameçons des palangres (poissons hachés, tels que des harengs, des maquereaux ou des thons).Pêcheurs et pêcheries. En plus des données scientifiques, un autre type de collecte des données a consisté à embaucher au hasard quelques pêcheurs professionnels exerçant tout le long de la côte libanaise, avec la collaboration du Conseil national libanais pour la recherche scientifique (CNRSL) -Centre national pour les sciences marines, et à pratiquer des pêches expérimentales au moyen de palangres à des profondeurs allant de 30 à 600 m afin de capturer des poissons cartilagineux d'un maximum d'espèces. La plupart des pêcheurs artisanaux libanais ne disposant pas de GPS, la position exacte des données collectées de cette manière n'a pas pu être enregistrée; cependant, la profondeur a pu être notée.La collecte des données a également consisté à visiter diverses poissonneries le long de la côte libanaise au minimum 5 fois par mois. La principale poissonnerie visitée était localisée à Tripoli, où les captures de poissons cartilagineux étaient constantes.Mesures morphométriques. Pour tous les échantillonnages réalisés, lorsque des spécimens étaient disponibles diverses données biologiques ont pu être collectées, en plus de leur identification.Les espèces ont été identifiées selon divers guides d'identification des poissons de la Méditerranée orientale et les sexes étaient différenciés afin d'en déduire le sexe-ratio. Diverses mesures ont été prélevées pour chaque spécimen : la longueur totale, la longueur de la fourche et la longueur extérieure des ptérygopodes (uniquement pour les spécimens de sexe masculin).Indices biologiques. Des dissections ont également été effectuées et des mesures supplémentaires ont été prises en plus du poids total: le poids du foie et des gonades (y compris le poids des testicules pour les mâles, et celui des glandes accessoires, des ovaires et oviductes pour les femelles) au moyen d'une balance électronique. Ces mesures ont été utilisées pour calculer des indices biologiques importants, tels que l'indice hépato-somatique (nécessaire pour l'étude des fonctions biologiques du fait que le foie est un accumulateur d'énergie important pour les poissons), l'indice de gonado-somatique (détermine les variations de poids des gonades au long du processus de maturation par rapport au poids du poisson) et le facteur de condition (indique les périodes de stress ou de phénomènes physiologiques, tels que, le frai, l'accouplement, les modifications de la densité de la population, les conditions d'alimentation, ou les variations de température). Après l'enlèvement des systèmes digestifs et de reproduction, le poids éviscéré des poissons a également été noté.Maturité sexuelle. Après identification, le type de reproduction (ovipares ou vivipares aplacentaire) des spécimens issus des captures a été déterminé au moyen de divers guides méthodologiques. Lors de la dissection, la maturité sexuelle de chaque élasmobranche capturé a également été déterminée par l'observation des gonades mâles et femelles par l'observation de l'aspect des gonades pour les élasmobranches vivipares aplacentaire.Analyse des contenus stomacaux. L'analyse des contenus stomacaux n'a été réalisée dans cette étude que pour l'espèce Rhinobatos rhinobatos, pour laquelle plusieurs estomacs étaient pleins.Au cours de la dissection de cette espèce cible, les estomacs ont été enlevés et leurs poids totaux ont été mesurés. Les estomacs contenant de la nourriture ont été préservés dans du formaldéhyde 4% jusqu'à identification du contenu. Le nombre d'estomacs vides a également été noté. Chaque proie a été identifiée au plus proche taxon possible et comptabilisé. Le poids total de chaque groupe proie a été mesuré si possible au gramme le plus proche. Composition du régime alimentaire. Le coefficient de vacuité, reflétant la richesse ou le manque de nourriture dans l'environnement a été calculé et le pourcentage de remplissage de l'estomac a été évalué et classé par catégories. De plus, trois indices ont été calculés pour montrer l'importance des différentes proies dans le régime alimentaire des espèces cibles : la fréquence d'occurrence, le coefficient d'abondance numérique des proies et les pourcentages de poids. Ces trois indices ont servi au calcul d'un 4ème indice, l'indice d'importance relative, afin de mieux refléter l'importance de chaque proie dans les estomacs des espèces cibles. Stratégie nutritives. Enfin, des pourcentages de l'indice d'importance relative ont été établis pour chaque type de proie afin de faciliter les comparaisons entre les types d'aliments. La stratégie d'alimentation de l'espèce cible a été analysée afin d'illustrer en particulier la dominance et la rareté de chaque groupe de proies durant les deux saisons et de la stratégie d'alimentation (spécialiste ou généraliste). Captures par unité d'effort. La capture par unité d'effort (CPUE) a été calculée seulement pour les espèces cartilagineuses capturées au cours de l'échantillonnage scientifique CIHEAM-PESCA Libano, au cours duquel des palangres, trémails et filets maillants ont été déployés à des traits spécifiques avec des coordonnées et des profondeurs prédéterminées. La CPUE pour les poissons cartilagineux pris lors de l'échantillonnage a été calculée au moyen du logiciel statistique 'R ' en kilogrammes et en nombre. Chapitre IV -Diversité et relations longueur-Poids Chapitre IV -Partie 1. Diversité, distribution et abondance des élasmobranches le long de la côte libanaise et principaux facteurs influents (Méditerranée orientale). Dans une première partie du chapitre 4, l'accent a été mis sur les différents aspects de la distribution spatiale et saisonnière, la diversité, la biologie et l'écologie des élasmobranches. Cette étude constitue la seule évaluation des ressources en élasmobranches le long de la côte libanaise, en Méditerranée orientale. Les données concernant les poissons cartilagineux sont issues de captures obtenues à partir de deux méthodes de collecte de données complémentaires, issues : (a) du projet scientifique CIHEAM PESCA-Libano réalisé avec la participation du Ministère de l'Agriculture et le Centre national pour les sciences marines -Conseil national libanais pour la recherche scientifique (CNRSL) et (b) des poissonneries et des pêcheurs. Au cours du suivi scientifique, des filets maillants expérimentaux, trémails et palangres ont été déployés à des profondeurs allant jusqu'à 600 m en 2013. Les poissons cartilagineux issus des données commerciales ont été recueillis auprès des principales poissonneries, qui ont été visitées périodiquement le long de la côte libanaise et de captures issues de pêches expérimentales réalisées avec des pêcheurs pendant la même année. La capture par unité d'effort a été utilisée comme un indice de l'abondance des élasmobranches capturés et a montré des variations saisonnières et spatiales de distribution et selon la profondeur. L'utilisation de données scientifiques et commerciales de manière complémentaire a permis de constituer une image plus précise de l'effet de la pêche sur les espèces d'élasmobranches. Au total, 314 spécimens de poissons cartilagineux ont été échantillonnés dont 25 espèces de poissons cartilagineux, 11 espèces de requins et 14 espèces de batoïdes. Aucune chimère n‗a été enregistrée. Les requins échantillonnés étaient constitués majoritairement des espèces : Centrophorus granulosus, Galeus melastomus, Squalus blainville et Mustelus mustelus. La majorité des batoïdes était constituée de Rhinobatos rhinobatos, Rhinobatos cemiculus, Torpedo marmorata, Torpedo nobiliana, Raja miraletus et Raja clavata. Les différents spécimens de poissons cartilagineux ont été pêchés à des profondeurs allant de 10 à 600 m. La diversité spatio-temporelle a également été évaluée et a montré des valeurs plus élevées dans la région sud de la côte et pendant les saisons de printemps et d'hiver. Cette étude peut servir de base pour évaluer les menaces des opérations de pêche et être une base de réflexion pour la mise en place de mesures de conservation possibles pour les espèces de poissons cartilagineux le long de la côte Libanaise en vue d'une gestion plus durable des ressources. Chapitre IV -Partie II. Les relations longueur-poids de trois requins et cinq batoïdes dans les eaux marines libanaises, Méditerranée orientale. Dans la seconde partie du chapitre 4, des relations taille-poids ont été présentées pour 8 espèces d'élasmobranches, 3 requins et 5 batoïdes, dans les eaux marines libanaises, en Méditerranée orientale. Ces élasmobranches ont été collectés à l'aide de palangres, trémails et filets maillants de décembre 2012 à octobre 2014. Les valeurs du paramètre b des relations longueur-poids W = aL b allaient de 1.752 à 3.337. Les relations poids-longueur ne variaient pas selon le sexe, sauf pour le requin Centrophorus granulosus (Bloch & Schneider 1801) et le batoïdes Torpedo marmorata (Risso 1810). Ces relations ne doivent être appliquées que dans les gammes de longueurs observées. Dans les 2 avant derniers chapitres de la thèse, un focus a été porté sur la biologie et l'écologie de deux espèces commercialement importantes et bien exploitées dans les eaux côtières libanaises. Ainsi, la biologie des populations du batoïde Rhinobatos rhinobatos (chapitre V) et du requin Centrophorus granulosus (chapitre VI) a été évaluée séparément sur des individus issus des deux sources de données combinées (scientifiques et commerciales). Chapitre V -Biologie des populations d'une espèce en voie de disparition : la guitare de mer commune Rhinobatos rhinobatos L. 1758 dans les eaux marines libanaises, Méditerranée orientale Le chapitre 5 a été consacré à l'étude de la biologie et l'écologie de la population de la guitare de mer commune Rhinobatos rhinobatos L. 1758, qui est répertoriée sur la liste rouge par l'Union Internationale pour la Conservation de la Nature comme une espèce de poisson cartilagineux en voie de disparition. Bien que fortement exploitée, jusqu'à maintenant, aucune étude n'a été menée sur cette espèce d'élasmobranches le long de la côte libanaise dans le bassin Levantin en Méditerranée orientale. Un total de 67 spécimens a été recueilli par les palangriers de fond issus des différents ports des eaux marines côtières libanaises à des profondeurs allant de 10 à 110 m entre décembre 2012 et janvier 2014. La longueur totale des spécimens de l'échantillon variait entre 50 et 143 cm avec une moyenne de 76,21 ± 19,7 cm. Les classes de taille les plus courantes se répartissaient entre 60 et 70 cm de longueur totale. Le poids total des échantillons se situait entre 410 et 10000 g avec une valeur moyenne de 1841,3 ± 1,987 g. Le sexe-ratio n'était pas significativement différent de 1:1 avec un nombre total de 34 mâles et 33 femelles. La relation longueur-poids a montré une croissance allométrique positive avec b = 3.096 et R 2 = 0,99. La longueur à laquelle 50% des individus étaient mâtures était de 84,73 ± 5,81 cm pour les femelles et 78,57 ± 4,88 cm pour les mâles. Les indices gonado-somatique et hépato-somatiques ainsi que le facteur de condition ont été représentés, et la parturition semblaient avoir eu lieu en hiver. Les principales proies trouvées dans les estomacs appartenaient à la famille Penaeidae en automne et en hiver. Les résultats de cette étude aideront à paramétrer les modèles de dynamique des populations de ce stock de poisson exploité afin d'assurer la durabilité à long terme de cette pêche. Chapitre VI -Biologie de la population du squale chagrin Centrophorus granulosus (Bloch & Schneider 1801) dans les eaux marines libanaises, Méditerranée orientale Le chapitre 6 a porté sur la biologie et l'écologie de la population du squale chagrin Centrophorus granulosus (Bloch et Schneider 1801) dans les eaux côtières libanaises. Bien que fortement exploitée en tant que prise accessoire, aucune étude n'a été menée sur cette espèce d'élasmobranches dans ce domaine. Un total de 38 individus a été recueilli à partir des eaux marines côtières libanaises au moyen de palangries de fond et de trémails de maillages différents, à des profondeurs allant de 115 à 600 m entre mai 2013 et février 2014. La longueur totale de l'échantillon variait entre 45 et 94 cm avec une moyenne de 80,64 ± 9,97 cm. La majorité des mâles et des femelles occupait des classes de taille dont la longueur allait de 70 cm à 80 cm au total, respectivement. Le poids total des échantillons variait de 870 à 6700 g avec une valeur moyenne de 1312,58 ± 3,791 g. Le sexe-ratio n'était pas significativement différent de 1:1 avec 20 mâles et 18 femelles. Une ségrégation sexuelle bathymétrique a été observée pour cette espèce. La Capture par Unité d'Effort a été utilisée comme un indice d'abondance relative pour détecter la distribution spatiale. La relation longueur-poids, l'indice gonado -somatique, l'indice hépato-somatique, et le facteur de condition du squale chagrin dans la zone d'étude ont également été présentés. Chapitre VII -Discussion générale, conclusion et perspectives Les élasmobranches sont soumis à diverses menaces à travers le monde, en particulier en mer Méditerranée, considérée comme l'une des trois principales régions où la diversité des élasmobranches est menacée. Dans ce contexte, deux principaux aspects ont été abordés : -La distribution et la diversité de ces poissons le long de la côte libanaise ; -L'approfondissement des connaissances relatives à certains traits d'histoire de vie de deux espèces d'élasmobranches majoritairement exploitées dans la région. Distribution, diversité et pêche au Liban. Le nombre d'espèces d'élasmobranches inventorié dans cette étude le long de la côte libanaise constituait un peu plus de 30% de toutes les espèces présentes en Méditerranée, et il était inférieur à celui enregistré dans plusieurs régions de la Méditerranée orientale, telles que Chypre (45 espèces), la Turquie (63 espèces), la Syrie (38 espèces) et Israël (57 espèces). Les fluctuations et les pics des indices de diversité des chondrichthyens selon les saisons et les régions le long de la côte libanaise ont été étudiés. Dans ce contexte, il est indispensable de conserver cette diversité pour maintenir la stabilité de l'écosystème (du fait que les élasmobranches sont des prédateurs à haut niveau trophique) et de protéger la qualité globale de l'environnement. Aires marines protégées. Les résultats de cette étude relatifs à la diversité de ces espèces peuvent inciter à plus long terme à la création de nouvelles Aires Marines Protégées (AMP) le long du littoral libanais, en plus des 2 AMP existantes au Liban. En effet, une plus grande surface d'AMP le long de la côte libanaise pourrait améliorer et stimuler la gestion de la pêche au sein et autour de la zone protégée, et par la suite renforcer la protection des organismes marins sensibles, comme les chondrichtyens. En effet, les coeurs de réserve des AMP constituent de précieux atouts pour faciliter la gestion durable des ressources halieutiques. L'interdiction des activités de pêche durant les saisons de reproduction ou sur les zones de nurseries permet d'accélérer la restauration des ressources sensibles et vise à long terme une meilleure protection du littoral. D'après le fait que la plupart des opérations de pêche se déroulent dans le nord du pays et les résultats obtenus sur la diversité des élasmobranches au Liban, indiquant qu'une plus grande diversité et abondance ont été observées dans le sud, nous pouvons émettre l'hypothèse que la diversité des élasmobranches pourrait être déjà altérée dans le nord par la pêche. Ainsi, nous pouvons suggérer que la création de nouvelles AMP devrait être développée dans les zones du nord du Liban. Aussi, la mise en oeuvre d'une plus grande AMP dans le sud permettrait d'améliorer la préservation de l'importante diversité observée dans cette région. En outre, nous pourrions proposer la mise en place de mesures spécifiques dans les zones marines autour des deux réserves naturelles côtières libanaises dont l'existence pourrait rendre ces mesures plus faciles à implémenter. Indice d'abondance. L'analyse des captures par unité d'effort, utilisées en tant qu'indice d'abondance, a fourni des indications sur les variations spatio-temporelles de la distribution et de l'abondance des élasmobranches. Ces variations pourraient être attribuables soit à l'environnement soit aux impacts anthropiques. La nature des eaux libanaises, la disponibilité des proies, les mouvements journaliers pour l'alimentation et saisonniers pour la reproduction, ainsi que les techniques de pêche employées ou les profondeurs de pêche peuvent expliquer la variation de la répartition et de l'abondance observée pour ces poissons. Certains engins utilisés au cours de l'échantillonnage n'ont pas été uniformément déployés tout au long de la côte, à toutes les strates de profondeur, et toutes les saisons. Par exemple, les palangres n'ont été déployées que dans le sud en raison notamment du manque de moyens financiers et de raisons politiques (conflits dans le nord du pays à Tripoli au cours de la période d'échantillonnage). En raison de l'unicité de cette étude dans la région, aucune tendance ne peut être estimée concernant les variations de l'abondance et de la biomasse des poissons cartilagineux des eaux côtière libanaises.En outre, la présente étude a utilisé des informations provenant de données issues de pêches scientifiques et commerciales. Les données commerciales ont l'avantage de ne pas provoquer de mortalité accrue, mais sont moins précises en raison de l'absence de systèmes de positionnement global (GPS). Les données scientifiques ont l'avantage d'être standardisées. L'utilisation conjointe de ces deux types de données dans cette dernière étude a permis d'améliorer l'estimation des CPUE.Variations spatio-temporelles. La sélection de l'habitat par les élasmobranches dépend de plusieurs facteurs biotiques et abiotiques. En particulier, la température et la profondeur sont à l'origine de la plus grande part de la variation spatiale de la composition des communautés de poissons démersaux. La structure de l'habitat est un autre facteur pouvant influencer la distribution des élasmobranches côtiers et des assemblages de poissons osseux associés. Par conséquent, l'étude des facteurs abiotiques, tels que la structure bathymétrique des fonds ou les types de sédiments associés à la présence de chondrichtyens pourrait aussi fournir plus d'informations sur les variations de la répartition spatiale observée. Dans cette étude, nous avons été confrontés à un manque de données sur le type de sédiments et bathymétriques le long de la côte libanaise. Il aurait été intéressant d'effectuer un échantillonnage du fond lors de chaque pose d'engins afin d'associer la présence des élasmobranches capturés à la structure de fond. Identification des espèces. L'identification et la déclaration des poissons cartilagineux à partir des captures est presque absente au Liban du fait du manque de scientifiques travaillant dans ce domaine. Les pêcheurs ne précisent que les noms généraux pour ces poissons, parfois en donnant un nom pour plusieurs espèces de morphologie presque similaire. De nombreux autres pays ont aussi des difficultés pour identifier les espèces capturées. Dans ce contexte, les codes-barres ADN (barcoding) constituent une méthode qui pourait révolutionner l'identification des espèces et réduire les problèmes liés aux mauvaises identifications. L'utilisation des techniques moléculaires est devenue une technique désormais acceptée pour identifier les espèces de requins ou pour confirmer l'identification morphologique des espèces notamment à partir de parties du corps des spécimens morphologiquement difficiles à identifier, telles que les ailerons. Le barcoding a déjà été appliqué aux élasmobranches et cette méthode a pu montrer dans certaines études des niveaux élevés de substitutions frauduleuses des ventes de requins et a permis d'identifier des espèces en voie de disparition parmi un échantillon d'ailerons de requins confisqués sur certains marchés notamment au Brésil. Manque de carnets de pêche et relations poids-longueur. En outre, le manque de carnets contenant toutes les informations de capture des pêches libanaises est une des raisons du fait que les CPUE n'ont pas pu être estimées pour les élasmobranches collectés à partir des pêcheries. A défaut, seule la biomasse a pu être évaluée. Cette étude a présenté également des données longueur-poids de 8 élasmobranches, dont certains ayant un statut d'espèce menacée sur la liste rouge de UICN. Par conséquent, les relations longueur-poids présentées dans cette étude sont uniquement utiles et efficaces pour les populations d'élasmobranches de la côte libanaise et pour les gammes de longueur et les sexes spécifiques étudiés. Traits d'histoire de vie et sur-exploitation. La surpêche chronique des élasmobranches a réduit les tailles de ces populations, et les populations initialement plus grandes ont été fragmentées en des populations plus réduites, localement isolées(Nadon et al., 2012)(Nadon et al., 2012), et a amené à des cascades trophiques. Malgré ce déclin rapide, des lacunes persistent concernant les leurs capacités à se maintenir et à se rétablir suite aux divers impacts anthropiques. En Méditerranée, peu d'informations sont disponibles sur l'organisation générale, la structure et la complexité des relations sociales entre les requins. Des études en milieux tropicaux ont montré que ces relations peuvent être assez complexes selon les espèces et jouer un rôle important dans leur répartition saptio-temporelle. Les résultats de cette thèse montrent que la guitare de mer commune, Rhinobatos rhinobatos, est l'espèce d'élasmobranches la plus souvent ciblée et capturée dans les pêcheries à la palangre libanaises, en particulier à Tripoli, avec une valeur commerciale significative. Bien que déclarée éteinte dans le nord de la Méditerranée, elle persiste dans les régions du sud de la Méditerranée, en particulier dans le golfe de Gabès. Limiter la pêche des élasmobranches est la principale mesure qui devrait être appliquée (renforcement du contrôle des ports et de la pêche, fixer des quotas de pêche, renforcer le nombre d'AMPs,…). Des actions de sensibilisation devraient être également entreprises auprès de la communauté de pêcheurs afin de mieux les informer sur l'importance des élasmobranches en tant que prédateurs de haut niveau trophique dans l'écosystème marin. En outre, une analyse conventionnelle du contenu stomacal a été réalisée pour la guitare de mer commune afin d'approfondir certains aspects biologiques de cette population. Cette analyse n'a pu être effectuée pour Centrophorus granulosus du fait que tous les estomacs étaient vides. L'utilisation de techniques d'analyses des isotopes aurait permis de limiter certains biais de la technique employée. L'utilisation des rapports isotopiques du carbone et de l'azote mesurés dans les tissus des consommateurs comme traceurs écologiques repose principalement sur le fait que les différents producteurs primaires d'un écosystème ont des compositions isotopiques différentes. Elles sont dues aux différents nutriments fixes qui ont des compositions isotopiques différentes, aux différentes sources de carbone et d'azote utilisés, et/ou aux cycles biochimiques que ces producteurs primaires utilisent pour la photosynthèse. Les valeurs de δ15N sont plus utilisées comme indicateurs de la position trophique des organismes dans leur chaîne alimentaire et largement utilisées pour calculer le niveau trophique absolus des espèces dans de nombreux écosystèmes.Tout l'effort de la flotte libanaise est concentré dans les 6 miles nautiques avec un pourcentage plus élevé dans les 3 miles nautiques conduisant à une forte pression de pêche des ressources halieutiques sur la côte. En effet, il est illégal au Liban de pêcher au-delà de la limite des 6 miles nautiques et les bateaux de pêche ne sont pas équipés pour pêcher au-delà de cette distance de la côte. La présence d'élasmobranches dans les pêcheries est due à la demande et aux coutumes alimentaires locales, spécifiques à certaines régions le long de la côte. Les données collectées par les pêcheries sont suffisantes pour convenir que des mesures de gestion plus importantes devraient être mises en oeuvre pour limiter la capture des élasmobranches et interdire l'exploitation de ceux qui sont menacés selon l'IUCN.Par conséquent, la présente étude a montré que certaines mesures devraient être prises pour faciliter la conservation et la gestion durable de cette classe de poisson. Par exemple, par la réduction des prises accessoires (i.e par l'augmentation de la sélectivité de la pêche les choix des engins, des zones ou des saisons). Cette étude a également mis en lumière les lacunes concernant cette classe de poissons en Méditerranée orientale, en particulier, le manque d'études génétiques ou encore celles relatives à la distribution et à l'évaluation des stocks. La majorité des études sont axées sur les caractéristiques des traits d'histoire de vie des espèces telles que les cycles biologiques, la croissance, la reproduction et la nutrition. L'estimation de l'âge permet de calculer le taux de croissance, le taux de mortalité et la productivité, ce qui fait de l'âge l'une des variables les plus importantes pour estimer la situation d'une population et évaluer les risques associés à la surpêche. Les épines dorsales ont été prélevées sur le squale chagrin et des estimations d'âges seront réalisables à terme pour cette espèce.En outre, une perspective serait d'aborder la structure interne des testicules et des ovaires de chaque stade de maturité histologiquement afin de vérifier la maturité observée à l'échelle macroscopique et pour permettre une meilleure compréhension de la reproduction en terme d'acquisition de la maturité et des cycles de reproduction. Aussi, les techniques de marquage en permettant de suivre la présence d'un poisson ou d'un groupe de poissons particulier dans le temps et l'espace, fournit un outil important pour les gestionnaires des pêches et peut-être un autre moyen, rentable, fiable et direct pour collecter des données pour l'étude des populations.

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  Chondrichthyans; conservation; distribution; life history; Lebanon; Levantine basin Résumé L'objectif de cette étude était de contribuer à une meilleure compréhension des poissons cartilagineux des eaux côtières libanaises du bassin oriental de la Méditerranée. Dans ce contexte, les différents aspects relatifs à la distribution, la diversité, la biologie et l'écologie de ces espèces ont été développés. Au total, 315 spécimens de poissons cartilagineux ont été échantillonnés appartenant à 25 espèces, dont 11 espèces de requins et 14 espèces de batoïdes. Aucune chimère n'a été enregistrée. Les données ont été collectées à partir (a) de captures expérimentales dans le cadre du projet "CIHEAM PESCA-Libano" et (b) d'observations périodiques des poissons dans les poissonneries et capturés par les pêcheurs. A partir des données de captures expérimentales, la distribution spatio-temporelle a été évaluée à travers le calcul de ‗la capture par unité d'effort'. Cette dernière a été estimée à la fois à partir des données scientifiques et commerciales, en prenant en considération le nombre total d'espèces. Différentes relations longueur-poids ont été établies pour 3 requins et 5 batoïdes, et cela pour les espèces présentant un nombre d'individus supérieur à 10. Finalement, la biologie et l'écologie de deux espèces commerciales bien exploitées dans les eaux côtières libanaises ont été présentées.Mots clés:Chondrichthyens; conservation; distribution; traits de vie; Liban; Bassin Levantin

Table 1 :

 1 The subareas of Fishing Area 37 and its divisions(FAO, 2004)

	Subarea	Western Mediterranean	Central Mediterranean	Eastern Mediterranean		Black Sea
	Division Balearic	Gulf of Lions	Sardinia Adriatic Ionian Aegean Levant	Marmara Sea	Black Sea	Azov Sea
	Code on map	1.1	1.2	1.3	2.1	2.2	3.1	3.2	4.1	4.2	4.3

  GFCM/36/2012/3 and the Barcelona Convention, the Ministry of Agriculture issued decree number 1/1045 as of 13/12/2013, which set standards and prohibitions on fishing or selling certain species of sharks and rays such as the guitarfish Rhinobatos spp., the hammerheads Sphyrna spp., and other commercially targeted species (ANNEX III). Unfortunately, fishing is maintained and the law is not being efficiently implemented. Other elasmobranch species are also targeted by artisanal fishermen. For example, many heavy weighted sharks or rays such as members of the Hexanchidae, Carcharinidae or the Lamnidae for sharks and the Dasyatidae and Myliobatididae families for batoids are often encountered in fisheries in some Lebanese regions northern (Tripoli) and southern (Sidon) of the country. Such fish caught are cleaned and cut into fish filets to be sold to restaurants or walking-by customers with prices ranging from $4 to $6 per one kilogram.

  Lebanon is one of the smallest countries in the world having area of 10452 km 2 . It is located in the Levantine basin of the Mediterranean Sea, bordered by Syria from the north and east and occupied Palestine from the south. In general, Lebanon enjoys a typical Mediterranean climate with two very contrasting seasons: a winter that is cold and heavily wet and a summer that is

	1.1.	Overview of the region

long, hot and dry and two intermediate seasons (spring and autumn). Along the coast, winters are relatively mild and rainy where the annual temperature is relatively low, around 13 to 15°C

[START_REF] Abi Saab | of Managing Marine Resources in a Changing Climate -ICOSMaP Kuantan-Malaysia: Inter-Islamic Science and Technology Network on Oceanography[END_REF]

. In some cases, this temperature can decrease up to 30°C or 4°C especially in December and January. During summer, temperatures are relatively high and can reach 30 to 35°C and even a 38ºC temperature was observed in July and August

(United Nations Development Program, 1970; Compendium Statistique National, 2006;[START_REF] Abi Saab | of Managing Marine Resources in a Changing Climate -ICOSMaP Kuantan-Malaysia: Inter-Islamic Science and Technology Network on Oceanography[END_REF]

. Moreover, according to Abboud Abi

[START_REF] Abi Saab | of Managing Marine Resources in a Changing Climate -ICOSMaP Kuantan-Malaysia: Inter-Islamic Science and Technology Network on Oceanography[END_REF]

the mean monthly variation of sea surface temperature between 2000 and 2012 varied between a minimum of 17.82°C in March and a maximum of 29.71° C in August, and the mean monthly variation of air temperature varied between a minimum of 12.4°C in January and a maximum of 27.59°C in August (Figure

Table 4 :

 4 The technical features of the vessels used in the CIHEAM PESCA-Libano survey.

	Vessel number	Port	Gross tonnage (t)	Length (m)	Engine power in horse power (hp)
	1	Tyre	3.7	10	85
	2	Byblos	3	11	85
	3	Jounieh	2	8.75	36
	4	Ozaaii	5	9	60
	5	Sidon	3.5	8.80	24
	6	Dora	3	8.75	24

Table 5 :

 5 The different reproductive system aspects, sexual maturation states and maturity stages for the ovoviviparous elasmobranchs according to the MEDITS handbook (MEDITS, 2012).

	Sex	Reproductive system aspect	Maturation state	Maturity	Stage
		Claspers flexible and shorter than pelvic fins. Testes
	Male	small (in rays, sometimes with visible lobules).
		Sperm ducts straight and thread-like.
		Ovaries barely visible or small, whitish;	Immature	Immature	1
	Female	undistinguishable ovarian follicles. Oviductal (nidamental) gland may be slightly visible. Uterus is
		thread-like and narrow.
			Developing	Immature	2
		Ovaries enlarged with small follicles (oocytes) of
	Female	different size. Some relatively larger yellow follicles may be present. Ovaries lack atretic follicles.
		Developing oviductal gland and uterus.
		Claspers fully formed, skeleton hardened, rigid and
	Male	generally longer than pelvic fins. Testes greatly enlarged; in sharks testes are fully segmented; in rays filled with developed lobules. Sperm ducts tightly	Spawning capable
		coiled and filled with sperm.		Mature	3a
		Large ovaries with enlarged yolk follicles all of about
	Female	the same size so that they can be easily distinguished. Ovidutcal gland and uterus developed without yolky	Capable to reproduce
		matter, embryos and not dilated.
	Male	Description similar to stage 3a, however with clasper glands dilated, often swollen and reddish (occasion-ally open). Sperm often present in clasper groove or	Actively spawning	Mature	3b

Male

Claspers slightly more robust but still flexible.

Claspers as long as or longer than pelvic fins. Testes enlarged; in sharks testes start to segment; in rays lobules clearly visible but do not occupy the whole surface. Sperm ducts developing and beginning to coil (meander).

Table 6 :

 6 The statistical methods performed in this study as well as their application purposes (L T , W T , F I , I G , I H , and K are total length, total weight, fullness index, gonado-somatic index, hepatosomatic index, and condition factor, respectively. G, L, and T are gillnets, long liners, and trammel nets, respectively. M, F, Imm, and Mat are males, females, immature and mature individuals, respectively.

	Statistical test	Description	Application (Chapter)
	R function
	Shapiro-Wilk test	Tests that the population is normally	Tested the normality of the samples
	shapiro.test	distributed.	in this study. (Chapters V & VI)
	Wilcoxon rank sum test	Also called the Mann-Whitney U	Tested the difference in L T , W T , and
		test. It is nonparametric and tests the	F I between males and females of a
	wilcox.test	difference between two populations.	certain species. (Chapters V & VI)
		It is efficient for non-normal	Tested the difference in L T and W T
		distributions and when variances are	of species caught between two types
		not equal.	of gear used. (Chapter VI)
	Kruskal-Wallis rank sum test	A nonparametric test efficient for	Tested the difference in L T and W T
		non-normal distributions and when	of a species according to the sexual
	kruskal.test	variances are not equal. It compares	maturity stages. (Chapters V & VI)
		two or more independent samples	Tested the difference in I G , I H , and K
		that may have different sizes.	of a certain species according to
			season. (Chapters V & VI)

Pairwise Test for Multiple Comparisons of Mean Rank Sums (Post Hoc; Nemenyi-Tests)

	Calculates	pairwise	multiple	Used after significant differences in
	comparisons between group levels.	the Kruskal-Wallis rank sum tests
				for pairwise multiple comparisons of
				the ranked data. (Chapter VI)
	Package: PMCMR
	posthoc.kruskal.nemenyi.test

Pearson's chi-square test (goodness-of-fit or chi-square test for independence)

	Analysis of covariance (ANCOVA)	Compares two or more regression	Performed a statistical comparison
				lines by testing the effect of a	of	length-weight	relationships
	anova			categorical factor on a dependent	between sexes of the same species.
				variable while controlling for the	(Chapters IV, V, & VI)
				effect of a continuous covariable.
	Two-way Unbalanced ANOVA	Two-way crossed-factor multivariate	Performed two-way crossed-factor
				ANOVA (by Redundancy Analysis)	analysis on the total weight
	anova.2way.unbalanced		for balanced and unbalanced	according to several factors.
				designs, with permutation tests. For	Factors and modalities:	Region
	(Anderson and Legendre, 1999;	unbalanced designs, this function	(North, South); season (cold: spring
	Legendre and Anderson, 1999)	computes type III sums-of-squares.	and winter; hot: summer and
					autumn); depth ([0,400[; [400,600]);
					sexual maturity (mature; immature).
					(Chapter VI)
	Permutational	Multivariate	Analyzes variances using distance	Analysed the ‗Catch Per Unit Effort'
	Analysis	of	Variances	matrices using a permutation test	in kilograms and number as log
	(PERMANOVA)		with pseudo-F ratios.
	Package:
	Vegan
	adonis
				Tests if there is a significant	Tested the difference between the
				difference between expected and	expected and obtained sex ratio.
				obtained results in one or more	(Chapters V & VI)
				categories.	Tested the presence of an association
	chisq.test			Tests any association between two	between the sex or the sexual
				categorical variables from a single	maturity of the specimens caught
				population.	and the depth at which they were
					caught at.(Chapters VI)

Les poissons cartilagineux de la Méditerranée orientale: revue de la littérature sur la biologie, l'écologie et la distribution géographique de ces espèces Résumé

	Cette étude est dédiée à une synthèse bibliographique sur la biologie, l'écologie et la répartition
	géographique des poissons cartilagineux de la Méditerranée orientale. Le but de cette revue est
	de présenter les diverses études et leurs lacunes et les régions où les espèces de poissons
	cartilagineux sont peu présentes et étudiées.
	Un focus est porté sur les informations concernant les inventaires existants, la présence et la
	répartition, le statut, la conservation, l'âge et la croissance, les relations longueur-poids, les
	aspects de la reproduction, les habitudes de nutrition et d'alimentation et d'autres aspects du cycle
	de vie de ces espèces. Cette synthèse présente également les résultats issus d'un nouvel
	inventaire des poissons cartilagineux effectué le long de la côte libanaise, où ont été répertoriées
	25 espèces (11 requins et 14 batoïdes) appartenant à 15 familles entre 2012 et 2014. La synthèse
	indique que les captures accidentelles de ces poissons est à l'origine de leur déclin en mer
	Méditerranée. Cette étude confirme également la présence de lacunes dans les études relatives
	aux espèces de poissons cartilagineux, avec certaines régions faisant l'objet de nombreuses
	études alors que peu d'études voire aucune n'existe dans d'autres régions de la Méditerranée
	orientale, comme la côte libanaise. Cette revue devrait permettre d'aider à une meilleure
	compréhension, gestion, et protection de cette catégorie de poissons menacés.
	Mot clés : Traits d'histoire de vie ; structure de population ; répartition spatiale et saisonnière

Table 7 :

 7 The cartilaginous fish species (Chondrichthyes) caught or observed in the Eastern Mediterranean according to the updated inventories in literature.

	Order

(Nelson, 2006) Family (Nelson, 2006) Cyprus (Hadjichristophorou, 2006) Along the Lebanese coast between 1973 and 1983 (Mouneimne, 2002) Along the Syrian coast in 2003 (Ali, 2003; Saad et al., 2004) In Turkey, Levantine and Aegean Seas (Bilecenoglu et al., 2014) Along the coast of Israel (Golani, 2006) Lamniformes

			Scyliorhinus canicula Dipturus oxyrinchus		Scyliorhinus oxyrinchus	Scyliorhinus circularis	Scyliorhinus Raja miraletus
			Scyliorhinus stellaris		canicula	canicula Leucoraja fullonica	canicula Raja montagui
						Scyliorhinus Leucoraja naevus	Raja radula
						stellaris Raja clavata	Raja undulata
		Sphyrnidae	Sphyrna zygaena Sphyrna mokarran	Sphyrna zygaena		Raja miraletus Sphyrna zygaena Raja asterias Raja radula	Sphyrna zygaena
	Hexanchiformes Carcharhiniformes Torpediniformes Pristiformes Squaliformes Myliobatiformes Echinorhiniformes Squatiniformes Chimaeriformes	Lamnidae Dalatiidae Etmopteridae Oxynotidae Cetorhinidae Odontaspididae Alopiidae Hexanchidae Carcharhinidae Torpedinidae Pristidae Centrophoridae Squalidae Dasyatidae Gymnuridae Echinorhinidae Squatinidae Chimaeridae	Carcharodon carcharias Isurus oxyrinchus Lamna nasus Dalatias licha Etmopterus spinax Oxynotus centrina Carcharias Taurus Odontaspis ferox Alopias vulpinus Hexanchus griseus Heptranchias perlo Carcharhinus brevipinna Carcharhinus melanopterus Carcharhinus plumbeus Prionace glauca Torpedo marmorata Torpedo nobiliana Torpedo torpedo Centrophorus granulosus Squalus acanthias Squalus blainville Pteroplatytrygon violacea Dasyatis pastinaca Dasyatis centroura Gymnura altavela Squatina squatina Squatina oculata	Isurus oxyrinchus Odontaspis ferox Hexanchus griseus Carcharhinus limbatus Prionace glauca Torpedo torpedo Torpedo marmorata Pristis pectinate Squalus acanthias Dasyatis pastinaca Himantura uarnak Gymnura altavela Squatina squatina Chimaera monstrosa	Isurus oxyrinchus Dalatias licha Somniosus rostratus Oxynotus centrina Alopias superciliosus Hexanchus griseus Heptranchias perlo Carcharhinus obscurus Carcharhinus plumbeus sinnuspersici Torpedo Torpedo nobiliana Torpedo marmorata Centrophorus granulosus Centrophorus acus Centrophorus moluccensis Centrophorus machiquensis Centrophorus uyato Squalus blainville Squalus megalops Pteroplatytrygon violacea Dasyatis pastinaca Dasyatis tortonesei Gymnura altavela Squatina squatina Squatina aculeata Squatina oculata Chimaera monstrosa	Carcharodon carcharias Isurus oxyrinchus Lamna nasus Dalatias licha Raja montagui Raja polystigma Etmopterus spinax Raja undulata Oxynotus centrina Rostroraja alba Cetorhinus maximus Carcharias taurus Odontaspis ferox Alopias vulpinus Alopias superciliosus Hexanchus griseus Heptranchias perlo Carcharhinus brevipinna Carcharhinus limbatus Carcharhinus altimus Prionace glauca Torpedo torpedo Torpedo nobiliana Torpedo marmorata Carcharhinus plumbeus Centrophorus granulosus Squalus acanthias Squalus blainville Dasyatis centroura Dasyatis marmorata Dasyatis pastinaca Dasyatis tortonesei Himantura uarnak Pteroplatytrygon violacea Taeniura grabata Echinorhinus Gymnura altavela brucus Squatina squatina Squatina aculeata Squatina oculata Chimaera monstrosa	Dalatias licha Carcharodon Etmopterus spinax carcharias Isurus oxyrinchus Oxynotus centrina Lamna nasus Cetorhinus maximus Carcharias taurus Odontaspis ferox Alopias vulpinus Alopias superciliosus Hexanchus griseus Heptranchias perlo obscurus Carcharhinus plumbeus Prionace glauca Torpedo torpedo Torpedo nobiliana Torpedo marmorata Carcharhinus Pristis pectinata Centrophorus granulosus Squalus acanthias Dasyatis centroura Dasyatis marmorata Dasyatis pastinaca Dasyatis tortonesei Himantura uarnak Pteroplatytrygon violacea Taeniura grabata Squalus blainville Carcharhinus altimus Carcharhinus brevipinna Carcharhinus limbatus Gymnura altavela Squatina squatina Squatina aculeata Squatina oculata Chimaera monstrosa
	Rajiformes	Triakidae Rhinobatidae	Galeorhinus galeus Mustelus asterias Mustelus mustelus Mustelus punctulatus Rhinobatos rhinobatos Rhinobatos cemiculus Raja clavata	Mustelus mustelus Rhinobatos rhinobatos Rhinobatos cemiculus	Mustelus mustelus Rhinobatos rhinobatos Rhinobatos cemiculus Raja clavata	Galeorhinus galeus Mustelus asterias Mustelus mustelus Mustelus punctulatus Rhinobatos rhinobatos Rhinobatos cemiculus Dipturus batis	Mustelus asterias Mustelus mustelus Rhinobatos rhinobatos Rhinobatos cemiculus Dipturus
	Carcharhiniformes	Scyliorhinidae Rajidae	Galeus melastomus Raja miraletus Raja asterias	Galeus melastomus Galeus melastomus Galeus melastomus Galeus melastomus Dipturus oxyrinchus Raja miraletus Dipturus oxyrinchus Raja miraletus Raja radula oxyrinchus Raja asterias
			Raja radula		Dipturus	Leucoraja	Raja clavata

Species recorded in Lebanon during this thesis research Mediterranean Sea Red Sea Atlantic Ocean Pacific Ocean Indian Ocean Eastern Central Western Eastern Central Western

	Carcharhinus obscurus	x	x	x	x	x
	Centrophorus granulosus	x		x	x	x	x
	Dalatias licha	x		x	x	x	x
	Dasyatis marmorata	x		x
	Dasyatis pastinaca*	x		x
	Dasyatis tortonesei	x
	Dipturus oxyrinchus*	x		x
	Galeus melastomus*	x		x
	Gymnura altavela*	x		x	x
	Heptranchias perlo	x		x	x	x	x
	Hexanchus griseus*	x		x	x	x	x
	Isurus oxyrhincus*	x	x	x	x	x
	Mustelus mustelus*	x		x	x
	Pteromylaeus bovinus*	x		x
	Pteroplatytrygon	x		x	x	x
	violacea
	Raja clavata	x		x
	Raja miraletus*	x		x			x
	Rhinobatos cemiculus*	x		x
	Rhinobatos rhinobatos*	x		x
	Squalus blainville	x		x	x	x	x
	Squatina aculeata	x		x
	Squatina oculata	x		x
	Taeniura grabata	x	x	x			x
	Torpedo marmorata*	x		x
	Torpedo nobiliana	x		x	x

Table 9 :

 9

	Von Bertalanffy growth parameters

The Von Beralanffy growth parameters and age estimation methods for several cartilaginous fish species in different studies in the Eastern Mediterranean (L∞ = the asymptotic or maximum length (or width for some batoids); k = the growth coefficient; and t 0 =the age or time when length theoretically equals zero; M = Males; F = Females; N = Number of specimens; SM = Southeastern Mediterranean; NM = Northeastern Mediterranean; NAS = North Aegean Sea).

Table 10 :

 10

		Region	N	Length-weight			Coefficient of	Reference
	Species			relationship					determination (R 2 )
	Carcharhinus	Antalya Bay	1	Males:					-	Guven et al. (2012)
	plumbeus			W T =0.0626×L T	3.41
	Centrophorus	Antalya Bay	56	W T =0.001×L T	3.41	0.98	Guven et al. (2012)
	granulosus	Off the island	43	W T =3.46 × 10 -7 L T	3.40	-	Megalofonou	and
		of Crete							Chatzispyrou (2006)
	Chimaera	North Aegean	17	W T =0.0028×L T	2.82	0.98	Filiz and Bilge (2004)
	monstrosa	Sea
	Dalatias licha	Antalya Bay	3	Females:					-	Guven et al. (2012)
				W T = 0.0117×L T	3
	Dasyatis pastinaca	Iskenderun	146 Males :					Ismen (2003)
		Bay		3.17 W T = 0.02963×D W W T = 0.00237×L T 3.31	0.95 0.91
			110 Females :
				3.21 W T = 0.00091×D W W T = 0.01681×L T 3.44	0.94 0.94
		Iskenderun	417 W T = 0.0419×L T	3.3169	0.84	Basusta et al. (2012a)
		Bay
		North Aegean	71	W T = 0.00074×L T	3.55	0.96	Yigin	and	Ismen
		Sea							(2009b)
		Central	31	W T = 0.0102×L T	3.37	0.98	Ilkyaz et al. (2008)
		Aegean Sea
		Central	16	W T = 0.0023×L T	3.248	0.99	Ozaydın et al. (2007)

The length-weight relationships for cartilaginous fish species in several studies performed in the Eastern Mediterranean (W T : total weight; L T : total length; D W : Disk width; N: number of individuals).

Table 11 :

 11 The stomach content analysis studies and the general results for several cartilaginous fish species in the Eastern Mediterranean (N: The number of specimens).

	Species	Region	N		Prey	Index of	References
						Relative
						Importance
						(IRI)
					Sharks
	Centrophorus	Off the island of	43	-Teleosteans (main)	-	Megalofonou	and
	granulosus	Crete		-Cephalopods		Chatzispyrou (2006)
		Mediterranean	-	-Cephalopods (main)	-	Golani and Pisanty (2000)
		coast of Israel		-Meso-to
				bathypelagic fishes
	Dalatias licha	North Aegean Sea	2	-Cephalopods (main)	-	Karachle and Stergiou (2010)
				-Teleosteans
				-Crustaceans (rare)
	Galeus	North Aegean Sea	3	-Cephalopods (main)	-	Karachle and Stergiou (2010)
	melastomus			-Teleosteans
		North Aegean Sea	-	-Cephalopods	-	Kabasakal (2002b)
	Hexanchus	Turkish seas	12	-Teleosteans (main)	-	Kabasakal (2006)
	griseus			-Chondrychthyans
				-Marine mammals
				-Cephalopods
		Aegean sea	11	-Teleosteans (main)	-	Kabasakal (2004)
	Mustelus	North Aegean Sea	-	-Cephalopods	-	Kabasakal (2002a)
	mustelus
	Scyliorhinus	North Aegean Sea	34	-Cephalopods (main)	-	Karachle and Stergiou (2010)
	canicula			-Teleosteans
				-Crustaceans
				-Polychaetes
		Northeastern	146 -Teleosteans (main)	%IRI=52.00%	Filiz and Taskavak (2006a)
		Aegean Sea		-Crustaceans (main)	%IRI=42.07%
				-Polychaetes	%IRI=3.29%
				(secondary)
				-Cephalopods	%IRI=32.44%
				(secondary)
				-Sipunculida	% IRI=0.20%
				(occasional)
		North Aegean Sea	-	-Cephalopods	-	Kabasakal (2002a)
		North Aegean Sea	-	-Teleosteans	-	Kabasakal (2001)
				-Crustaceans
				-Cephalopods
				-Polychaetes
	Squalus	Northeastern	-	-Crustaceans (main)	IRI=7098.59	Kabasakal (2002d)
	blainville	Aegean Sea		-Teleosteans (main)	IRI=2734.8
				-	Liocarcinusspp.-	IRI=2072.74
				Parapenaeus	IRI=1143.2
				longirostris
					Batoids
	Dasyatis	North Aegean Sea	1	-Crustaceans (main)		Karachle and Stergiou (2010)
	pastinaca			-Polychaetes
		Iskenderun Bay	256 -Crustaceans (main)	-	Ismen (2003)

  studied 13 stations in the North Aegean Sea through sampling using a bottom trawl at depths ranging from 40 to 500 m. The study revealed that the most abundant cartilaginous fish species was Scyliorhinus canicula and it was caught at all depths. Torpedo marmorata, Raja

radula and Dipturus oxyrinchus were rarely caught. Moreover,

[START_REF] Maravelias | Habitat selection and temporal abundance fluctuations of demersal cartilaginous species in the Aegean Sea (Eastern Mediterranean)[END_REF]

and

[START_REF] Tserpes | Distribution of relatively rare demersal elasmobranchs in the eastern Mediterranean[END_REF]

analyzed the MEDITS scientific bottom trawl survey data for several cartilaginous fish species in the Aegean Sea covering an 11-year sampling period.

[START_REF] Maravelias | Habitat selection and temporal abundance fluctuations of demersal cartilaginous species in the Aegean Sea (Eastern Mediterranean)[END_REF]

studied two of the most abundant cartilaginous fish species (Scyliorhinus canicula, Raja clavata) and revealed a declining trend in the abundance of these two species from the late 1990s until 2004. The latter study also suggested that habitats with the higher probability of finding cartilaginous fish present were those located in intermediate waters (depth: 200-400 m), and depth appeared to be one of the key determining factors for the selection of habitats for all species examined. Besides,

[START_REF] Tserpes | Distribution of relatively rare demersal elasmobranchs in the eastern Mediterranean[END_REF]

analyzed the data for the demersal elasmobranchs Mustelus mustelus, Raja asterias, Torpedo marmorata and Galeus melastomus and revealed that both depth and geographical coordinates were the key determinants of the presence of all species, while annual abundance fluctuations were found to be either insignificant or without any specific trend. Finally,

[START_REF] Yeldan | Temporal changes in some Rajiformes species of cartilaginous fish (Chondrichthyes) from the west coast of İskenderun Bay (northeastern Mediterranean)[END_REF]

investigated the spatio-temporal changes in Catch Per Unit Effort (CPUE) of Dasyatis pastinaca, Gymnura altavela, Rhinobatos rhinobatos, Raja radula, Myliobatis aquila, and Torpedo marmorata by considering two depth contours (10 and 20 m) in Iskenderun Bay. The latter study revealed highly significant seasonal variations and year-season 2-way interactions for total cartilaginous CPUE values.

Table 12 :

 12 The sampling effort represented by the number of hauls where gear (G: gillnets; T: trammel nets; L: longlines) was lowered according to every combination of season, region (N: north; C: central; S: south), and depth strata.A quantitative representation of the scientific survey total CPUE (expressed in kilograms) according to species, season, region, and depth is presented in Table2. A total of 15 elasmobranchs (N=131), 4 sharks and 11 batoids, were caught during the scientific survey. CPUE for shark catches also varied according to depth and season. No sharks were captured during the summer season at depths less than 200 m and during the spring season at depths ranging from 200 to 400 m. The highest total CPUE was observed in winter (150 kg/unit effort), a lower one in spring (26.403 kg/unit effort), and the lowest was observed in summer (14.375 kg/unit effort). The CPUE for shark catches ranged from 5.450 kg/unit effort for C. granulosus to 150 kg/unit effort for H. griseus according to depth, region and season. In addition, regarding depth variation, the highest total CPUE (150 kg/unit effort) was displayed at depth stratum [0-

	The

Regarding all elasmobranchs, the total CPUE ranged from 0.051 kg/unit effort for T. marmorata to 150 kg/unit effort for H. griseus according to depth, region and season. The total CPUE varied with depth during all seasons. The general total was highest (198.401 kg/unit effort) in the depth class

[0-200[, displayed its minimum (19.

669 kg/unit effort) in depth class

[200-400[, and

showed a value of 21.776 kg/unit effort in the largest depth class

([400-600]

). The general total CPUE also varied seasonally displaying the highest value in winter (164.534 kg/unit effort), a lower value in spring (46.954 kg/unit effort), and the lowest in summer (28.358 kg/unit effort) (Table

13

).

200[ and the lowest was observed at depth stratum [400-600] (Table

13

). The CPUE of batoids ranged from 0.051 kg/unit effort for T. marmorata to 8 kg/unit effort for T. grabata. Batoids were observed in all depth strata; the highest total CPUE (31.473 kg/unit effort) was observed in

  lower one (12.301 kg/unit effort) in depth class, and the lowest (5.294 kg/unit effort) was observed in depth class were also observed in all seasons, showing the highest total CPUE in spring (20.551 kg/unit effort), a lower one in winter (14.534 kg/unit effort), and the lowest in summer (13.983 kg/unit effort) (Table13).Moreover, C. granulosus showed to be a prominent shark in the survey. It was observed in spring and summer in all depth strata with CPUE ranging from 5.450 to 10.328 kg/unit effort.The other sharks, D. licha, H. perlo, and H. griseus were observed in spring, summer and winter, respectively, at the depth strata[0-200[and [200-400[. Regarding batoids, the most prominent in the survey was R. clavata, which was observed in all seasons in depth strata ranging from 0.365 to 2.3 kg/unit effort. Similarly, T. marmorata showed the same latter seasonal and depth distribution with CPUE ranging from 0.280 to 1.127 kg/unit

effort; however, it was not observed in the winter season. Only D. oxyrinchus and P. violacea were observed at the largest depth stratum ([400-600]) with CPUE of 5.951 and 6.350 kg/unit effort, respectively. Some batoids were observed each in a single season and depth stratum; for example, D. pastinaca

(summer; [0-200[), G. altavela (summer; [0-200[), R. rhinobatos (spring; [0-200[), T. grabata (winter; [0-200[), and T. nobiliana (spring; [0-200[)

(Table

Total (N=103) 14.534 (8.83%) 7.305 (30.14%) 9.634 (100%) 0.945 (100%) 4.349 (23.22%) 12.301 (56.49%) General total of all elasmobranchs (N=131

	(Least Concern)	T	S		-	Batoids 0.13 (0.54%)	0.193 (2%)	-	-	-
	Dasyatis marmorata N=30	G, T	C		--	-0.13 (0.54%)	2.262 (23.48%) 0.992 (10.29%)	--	-0.692 (3.69%)	--
	(Data Deficient) Rhinobatos rhinobatos	L, G L	S S		4.234 (2.57%) -	-3.6 (14.86%)	0.518 (5.38%) -	--	--	--
	N=9 (Endangered)				4.234 (2.57%) -		2.780 (28.86%)	-	-	-
	Dasyatis pastinaca N=1	T	N		--	-3.6 (14.86%)	Depth (m) 1.521 (15.79%) ---	--	--
	(Data Deficient) Taeniura grabata	T L	C S		[0 -200[ -8 (4.86%)	--		1.45 (15.05%) -	[200 -400[ --	--	[400 -600] --
	Species N=2 (Data Deficient) (IUCN status) Dipturus oxyrinchus N=1	Gear caught with L	Region S	Winter --8 (4.86%)	Spring ---		Summer 2.971 (30.84%) --	Spring ---	Summer ---	Spring -5.951 (27.33%) -
	(Near Threatened) Torpedo marmorata	T	N		-	-	Sharks	0.362 (3.76%)	-	0.051 (0.27%)	-
	Centrophorus granulosus N=7 (Data Deficient)	T G, T	N C		---	---		--0.830 (8.61%)	---	5.450 (29.11%) --5.951 (27.33%) 0.534 (2.85%) -
	(Vulnerable) Gymnura altavela	T, L T T	S C S		---	10.328 (42.62%) ---1.127 (4.65%) 0.846 (8.78%)	--0.579 (61.27%)	-0.453 (2.43%) 0.280 (1.49%)	9.475 (43.51%) --
	N=22 (Vulnerable) N=22				--	10.328 (42.62%) -1.127 (4.65%) 2.038 (21.16%)	-0.579 (61.27%)	5.450 (29.11%) 9.475 (43.51%) 0.865 (4.61%) -
	Dalatias licha N=1 Torpedo nobiliana	T T	S S		---	6.6 (27.24%) -1.398 (5.76%)	---	---	-0.453 (2.43%) -	---
	(Near Threatened) Pteroplatytrygon (Data Deficient)	L	S		-	-		-	-	-	6.350 (29.16%)
	N=2 violacea N=7				--	6.6 (27.24%) 1.398 (5.76%)	--	--	--	--
	Heptranchias perlo (Least Concern)	T	C		-	-		-	-	8.925 (47.67%) -
	(Near Threatened) N=4				-	-		-	-	-	6.350 (29.16%)
	N=3 Hexanchus griseus (Near Threatened) Raja clavata	L T T	S C N	)	-150 (91.17%) -(100%) -164.534	----24.233 (100%)	--0.853 (8.85%) -9.634 (100%)	----0.945 (100%)	-1.153 (6.16%) 8.925 (47.67%) ---0.365 (1.95%) -18.724 (100%) 21.776 (100%)
	(Near Threatened)	G, T	S		2.3 (1.4%)	1.05 (4.33%)	-	0.366 (38.73%)	0.821 (4.38%)	-
	N=1 N=19				150 (91.17%) 2.3 (1.4%)	-1.05 (4.33%)	-0.853 (8.85%)	-0.366 (38.73%)	-2.339 (12.49%) --
	Total (N=28) Raja miraletus	G, T	C		150 (91.17%) -	16.928 (69.86%) --0.799 (8.29%)	--	14.375 0.692 (3.69%)	9.475 (43.51%) -
										(76.78%)

Table 15 :

 15 A Univariate 4-way PERMANOVA for the community matrix of log (CPUE(kg) +1) and log(CPUE(number) +1) (A), and a univariate 6-way PERMANOVA for the community matrix of log(W T +1) (B). All combinations of factors were tested but only significant results are presented (Sex. mat.: sexual maturity; the number in parenthesis is the number of individuals in each sample). The sign × means interaction between factors. The considered factors for survey data were: gear, region, depth and season; two additional factors (sex and sexual maturity) were considered for fishery data.

			All elasmobranchs (15)		Sharks (4)		Batoids (11)
		A
			Factor	F	P-value	Factor	F	P-value	Factor	F	P-value
	Survey	CPUE (kg)	Season	3.19	0.0002	Season	3.42	0.002	Season	2.7	0.0006
	data		Depth	3.35	0.008	Gear	4.19	0.041	Depth	6.04	0.0001
	Factors:		Gear	4.73	0.007				Gear	5.91	0.0004
			Season × Gear	3.03	0.049				Season × Gear	7.57	0.02
		CPUE	Season	2.55	0.001	Season	5.11	0.003	Depth	3.43	0.005
		(number)	Depth	3.44	0.002	Depth	3.47	0.042
			All elasmobranchs (17)		Sharks (8)			Batoids (9)
		B
			Factor	F	P-value	Factor	F	P-value	Factor	F	P-value
	Fishery/	Total	Season	3.96	0.007	Season	6.6	0.0072	Season	3.07	0.017
	Fishermen data	weight (kg)	Haul	9.23	0.0001	Haul	27.16	0.0001	Haul	3.25	0.026
			Depth	15.02	0.0001	Depth	49.59	0.0001	Depth	3.47	0.02
	Factors:		Sex. mat Season × Sex. mat.	4.21 2.56	0.002 0.023	Season × Depth × Sex	5.3	0.0251	Sex. mat Season × Sex.	5 2.97	0.002 0.03
			Sex × Sex. mat	3.28	0.007				mat.	3.79	0.011
			Season × Sex × Sex. mat.	2.34	0.037				Sex × Sex. mat.

Table 16 :

 16 The diversity indices used to evaluate spatial and seasonal diversity (S is the number of species in each sample; H': Shannon Index; J': Pielou's evenness; 1-D: Simpson's Index; ∆ + : Taxonomic distinctness).

		Spatial diversity		Seasonal diversity
		North	South	Autumn	Winter	Spring	Summer
	S	18	19	9	15	12	14
	H'	2.140280	2.312068	1.5226824 2.2717730 2.0186018 2.0242640
	J'	0.7404862	0.7852320	0.6930026 0.8388962 0.8123451 0.7670406
	1-D	0.8061828	0.8674317	0.6976744 0.8651860 0.8239721 0.8078125
	∆ +	90.277	92.188	87.0513	90.1289	92.1480	91.0861

Table 17 :

 17 The weight and length characteristics, as well as, the parameters of the LWR (W=aL b ) for the 8 elasmobranchs caught in the Lebanese waters. N is the sample size; mean, min, max, and SD are the mean, minimum, maximum, and standard deviation respectively; a and b are the parameters of the weightlength relationship; SE (b) is the standard error of parameter b; r 2 is the coefficient of determination; allometric (-) and allometric (+) is negatively and positively allometric respectively; M, F, and Both are the male, female, and the combined sample respectively.

				Weight and length characteristics Parameters of the LWR
				L mean ± SD	Wmean ± SD
	Species	Sex	N	(Lmin-Lmax) in centimeters	(Wmin-Wmax) in grams (g)	a	b	SE (b) r 2	Growth
				(cm)
					Shark species
				73.95±9.24	2705.75±616.84	0.3585	2.071 0.2351 0.9419 Allometric
	Centrophorus	M	20	(45 -83)	(870 -3400)				(-)
	granulosus
	(Bloch &			88.08±3.11	4997.22±631.17				Allometric
	Schneider, 1801)	F	18	(81 -94)	(3400 -6200)	0.02392	2.735 0.5563 0.6380	(-)
	Squalus			49.59±4.85	676.55±205.77	0.008192 2.894 0.4969 0.8238 Allometric
	blainvillei (Risso,	Both 11	(42 -57)	(367 -1050)				(-)
	1827)
	Galeus			48.64±4.48	360.81±119.41	0.003783 2.946 0.6328 0.6458 Allometric
	melastomus (Rafinesque,	Both 14	(41-55)	(110 -495)				(-)
	1810)
					Batoid species
	Rhinobatos			75.60±19.59	1793.53±1957.87	0.002138 3.102 0.0325 0.9873 Allometric
	rhinobatos	Both 70	(50 -143)	(410 -10000)				(+)
	(Linnaeus, 1758)
	Rhinobatos			82.93±16.49	2256.19±1898.02	0.004565 2.941 0.0365 0.9775 Allometric
	cemiculus			(57.80 -150)	(650 -11500)				(-)
	(Geoffroy Saint-	Both 31
	Hilaire, 1817)
	Raja clavata (Linnaeus, 1758 )	Both 19	47.42±12.28 (25 -70)	832.68±680.83 (62 -2300)	0.002970 3.203 0.3002 0.9765 Allometric (+)
	Raja miraletus (Linnaeus, 1758)	Both 30	34.62±3.86 (25 -44)	224.23±92.92 (72 -490)	0.001563 3.337 0.2321 0.9130 Allometric (+)
	Torpedo	M	16	25±3.49 (14 -30)	327.69±95.74 (51 -474)	0.3520	2.118 0.3125 0.9487 Allometric (-)
	marmorata
	(Risso, 1810 )	F	6	25.67±4.56 (18 -31)	400.50±127.38 (222 -550)	1.3367	1.752 0.4508 0.8994 Allometric (-)

de disparition : la guitare de mer commune Rhinobatos rhinobatos L. 1758 dans les eaux marines libanaises, Méditerranée orientale Résumé Cette

  étude est consacrée à la biologie et l'écologie de la population de la Guitare De Mer Commune Rhinobatos rhinobatos L. 1758, qui est répertoriée sur la liste rouge par l'Union Internationale pour la Conservation de la Nature (IUCN) comme une espèce de poisson

	3.096 et R 2 = 0,99. La longueur à laquelle 50% des individus étaient mâtures était de 84,73 ±
	5,81 cm pour les femelles et 78,57 ± 4,88 cm pour les mâles. Les indices gonado-somatique et
	hépato-somatiques ainsi que le facteur de condition ont été représentés, et la parturition
	semblaient avoir eu lieu en hiver. Les principales proies trouvées dans les estomacs appartenaient
	à la famille Penaeidae en automne et en hiver. Les résultats de cette étude aideront à paramétrer
	les modèles de dynamique des populations de ce stock de poisson exploité afin d'assurer la
	durabilité à long terme de cette pêche.
	Mots-clés: Chondrichthyens; IUCN; Liban; histoire de vie; surexploitation; biologie
	reproductive.

cartilagineux en voie de disparition. Bien que fortement exploitée, jusqu'à maintenant, aucune étude n'a été menée sur cette espèce d'élasmobranches le long de la côte libanaise dans le bassin Levantin en Méditerranée orientale. Un total de 67 spécimens issus de différents ports des eaux marines côtières libanaises a été recueilli par les palangriers de fond à des profondeurs allant de 10 à 110 m entre décembre 2012 et janvier 2014. La longueur totale des spécimens de l'échantillon variait entre 50 et 143 cm avec une moyenne de 76,21 ± 19,7 cm. Les classes de taille les plus courantes se répartissaient entre 60 et 70 cm de longueur totale. Le poids total des échantillons se situait entre 410 et 10000 g avec une valeur moyenne de 1841,3 ± 1,987 g. Le sexe-ratio n'était pas significativement différent de 1:1 avec un nombre total de 34 mâles et 33 femelles. La relation longueur-poids a montré une croissance allométrique positive avec b =

Table 18 :

 18 The mean, minimum (min) and maximum (max) lengths and weights of the females and males of the Common Guitarfish sample (S.D.: Standard deviation)

			Length (cm)		Weight (g)
		Number of	Mean	Min	Max	Mean	and	Min	Max
		individuals	and			S.D.
			S.D.
	Females 33	81.79 ±	58	143	2360.21 ±		628	10000
			23.07			2563.00
	Males	34	70.78 ±	50	114	1337.65 ±		410	5500
			14.09			997.88

Table 19 :

 19 Variation in the diet of Common Guitarfish in terms of the frequency of occurrence (O % ), coefficient of prey numerical abundance (N % ), percentage of weight (W % ), and percentage of the Index of Relative Importance (I %RI ) during the autumn and winter season.

			Autumn			Winter
	Prey group	O %	N %	W %	I %RI	O %	N %	W %	I %RI
	Penaeidae	64	33.33 26.20 44.20 66.67 46.67 37.72 57.01
	Brachyura	28	6.67	2.19	2.88 33.33 33.33 27.27 20.47
	Octopodidae	16	1.78	20.08	4.06	0	0	0	0
	Squilladae	32	13.33 23.01 13.49 11.11	2.22	4.45	0.75
	Teleostei	24	5.78	3.19	2.50 44.44 17.78 30.56 21.77
	Juvenile Nephropidae	44	39.11 25.33 32.89	0	0	0	0

Table 20 :

 20 The mean, minimum (min) and maximum (max) total lengths and weights of females and males of the Gulper Shark sample (S.D.: Standard deviation)

				Total length (cm) Total weight (g)
		Number of	Mean and	Min Max Mean and S.D.	Min	Max
		individuals	S.D.
	Females 18	88.08	±	81	94	4997 ± 631.17	3400	6200
			3.11
	Males	20	73.95	±	45	83	2706 ± 616.84	870	3400
			9.24

  Tyre Coast Nature Reservesouth; Palm Islands Nature Reservenorth), the Ministry of the Environment has proposed 9 coastal marine sites as MPAs

(Nakoura; Sidon Rocks; Raoucheh Cliffs and Caves; Beirut Port Outer Platform; Byblos; Madfoun Rocky Area; Batroun Phoenician Wall; Ras El Chekaa Cliffs; Enfeh Peninsula) (Lebanese Ministry of Environment-IUCN, 2012) (Figure

Table 1 :

 1 The subareas of Fishing Area 37 and its divisions(FAO, 2004)...................................... 6

Table 2 :

 2 The number of chondrichthyan species in each IUCN Red List category[START_REF] Cavanagh | Overview of the conservation status of cartilaginous Fishes (chondrichthyans) in the Mediterranean Sea[END_REF] ................................................................................................................................ 12

Table 3 :

 3 The alien chondrichthyans of the Mediterranean Sea..................................................... 16

Table 4 :

 4 The technical features of the vessels used in the CIHEAM PESCA-Libano survey...... 31

Table 5 :

 5 The different reproductive system aspects, sexual maturation states and maturity stages for the ovoviviparous elasmobranchs according to the MEDITS handbook (MEDITS, 2012). .. 36

Table 6 :

 6 The statistical tests performed in this study as well as their application purposes (L T , W T , F I , I G , I H , and K are total length, total weight, fullness index, gonado-somatic index, hepatosomatic index, and condition factor, respectively. G, L, and T are gillnets, long liners, and trammel nets, respectively. M, F, Imm, and Mat are males, females, immature and mature individuals, respectively. .............................................................................................................. 45

Table 7 :

 7 The cartilaginous fish species (Chondrichthyes) caught or observed in the Eastern Mediterranean according to the updated inventories in literature. ............................................... 59

Table 8 :

 8 The

concernant la langue de rédaction de la thèse.

  Tablecontainingall the species classified up to their class used to calculate the taxonomic distances using the function taxa2dist on ‗R project' The native distribution maps of the species recorded along the Lebanese coasts in this study[START_REF] Aquamaps | AquaMaps: Predicted range maps for aquatic species. World wide web electronic[END_REF] La langue des thèses et mémoires dans les établissements publics et privés d'enseignement est le français, sauf exceptions justifiées par les nécessités de l'enseignement des langues et cultures régionales ou étrangères ou lorsque les enseignants sont des professeurs associés ou invités étrangers. La maîtrise de la langue française fait partie des objectifs fondamentaux de l'enseignement. Pour les thèses en cotutelle, la langue dans laquelle est rédigée la thèse en cotutelle est définie par la convention conclue entre les établissements contractants.

	Parameter nobiliana H max L C L T L F L S W T W L W G W E I H I G K W S C V E V F I W P O % N P M N % n J' Tmarmorata Torpedo External length of claspers Total length Fork length Standard length Total weight Weight of the liver Weight of the gonads Eviscerated weight Weight of the stomach Percentage of fullness Weight of prey items in each stomach The frequency of occurrence The coefficient of prey numerical The maximum diversity where all group Torpedo Torpedinidae Torpediniformes evenness) The number of prey of each taxonomic Torpedinidae Torpediniformes Shannon evenness measure (Pielou's abundance grabata Taeniura Dasyatidae Myliobatiformes species Percent (%) Chondrichthyes Chondrichthyes Chondrichthyes n i oculata Squatina Squatinidae Squatiniformes Chondrichthyes The total number of individuals in the ith remains blainvillei Squalus Squalidae Squaliformes Chondrichthyes the ith species The number of stomachs with prey p i rhinobatos Rhinobatos Rhinobatidae Rajiformes Chondrichthyes The proportion of individuals found in specific prey group H' cemiculus Rhinobatos Rhinobatidae Rajiformes Chondrichthyes Shannon Index The number of stomachs containing a miraletus Raja Rajidae Rajiformes Chondrichthyes same sample Percent (%) N clavata Raja Rajidae Rajiformes Chondrichthyes The total number of individuals in the Grams (g) violacea Pteroplatytrygon Dasyatidae Myliobatiformes Chondrichthyes the sample Percent (%) S bovinus Pteromylaeus Myliobatididae Myliobatiformes Chondrichthyes The total number of species recorded in Number of empty stomachs E mustelus Mustelus Triakidae Carcharhiniformes Chondrichthyes Effort Coefficient of vacuity oxyrhincus Isurus Lamnidae Lamniformes Chondrichthyes gear; Index M: mesh) Grams (g) according to each meshed gear (Index G: griseus Hexanchus Hexanchidae Hexanchiformes Chondrichthyes (num/unit effort) Condition factor CPUE number,G,M Catch Per Unit Effort in number perlo Heptranchias Hexanchidae Hexanchiformes Chondrichthyes Number per unit effort Gonado-somatic index altavela Gymnura Gymnuridae Myliobatiformes Chondrichthyes or longline also in the predetermined haul Hepato-somatic index melastomus Galeus Scyliorhinidae Carcharhiniformes Chondrichthyes species i caught in the same meshed gear Grams (g) N Ci,G,M The total number of oxyrinchus Dipturus Rajidae Rajiformes Chondrichthyes cartilaginous Grams (g) tortonesei Dasyatis Dasyatidae Myliobatiformes Chondrichthyes gear; Index M: mesh) Grams (g) according to each meshed gear (Index G: pastinaca Dasyatis Dasyatidae Myliobatiformes Chondrichthyes (kg/unit effort) Grams (g) CPUE kg,G,M Catch Per Unit Effort in kilograms marmorata Dasyatis Dasyatidae Myliobatiformes Chondrichthyes Kilograms per unit effort Centimeters (cm) L S Standard length licha Dalatias Dalatidae Squaliformes Chondrichthyes Centimeters (cm) Centimeters (cm) L F Fork length granulosus Centrophorus Centrophoridae Squaliformes Chondrichthyes Centimeters (cm) Centimeters (cm) I %RI Percent of I RI Percent (%) obscurus Carcharhinus Carcharhinidae Carcharhiniformes Chondrichthyes class Millimeters (mm) I RI Index of relative importance aculeata Squatina Squatinidae Squatiniformes Chondrichthyes specimens in each determined length Abbreviation Full name Measurement unit W % The percentage of weight Percent (%) m The mass of prey of each taxonomic group Grams (g) m P The total mass of prey items species had equal abundances 1-D Simpson's Index ∆ + Taxonomic diversity/distinctness P The proportion of mature elasmobranch Genus Family Order Class Annex V: Species Annex VI: Préambule
	n P	The total number of prey items

Lorsque cette langue n'est pas le français, la rédaction est complétée par un résumé substantiel en langue française.

  Une synthèse d'une vingtaine de pages en français, intégrée au manuscrit, mettant en évidence les apports principaux du travail de thèse est requise par l'Ecole Doctorale 305.

	Résumé

substantiel de la thèse en langue française Biologie, distribution et diversité des poissons cartilagineux le long de la côte libanaise, Méditerranée orientale A

  l'heure actuelle, la biodiversité marine (fonctionnelle, spécifique génétique, taxonomique ou encore écosystémique) est menacée par l'augmentation des activités anthropiques. La surpêche notamment, en diminuant les effectifs des populations, peut affecter la diversité biologique des espèces, qui pour certaines ne sont plus en mesure de maintenir leur rôle fonctionnel au sein de la chaîne trophique, en tant que proie, prédateur, ou compétiteur, et peut aboutir à des extinctions écologiques et fonctionnelles. La faune marine récente de la mer Méditerranée est principalement dérivée de l'océan Atlantique, mais la variété de climats et l'hydrologie particulière de cette mer a contribué à la co-occurrence et à la survie d'organismes issus de régions tempérées et sub-tropicales. Bien que le bassin méditerranéen ne représente que moins de 1% de la surface de l'océan mondial, sa biodiversité est exceptionnelle pour une si faible surface. En effet, il comprend jusqu'à 18% des Les effets des activités humaines sont plus importants en Méditerranée en comparaison à toutes les autres mers du monde. Les connaissances sur les processus, la répartition écologique des espèces, l'état des écosystèmes et les causes de l'érosion de la biodiversité sont encore vagues, d'autant plus que la plupart du bassin méditerranéen est non géré et exposé à des menaces. Bon nombre des caractéristiques écologiques de la mer Méditerranée sont menacées avec des zones où des menaces potentielles élevées se cumulent, notamment au niveau des bassins occidental et oriental et dans une moindre mesure dans la région sud-est. Les causes les plus importantes des menaces actuelles et futures pour les espèces méditerranéennes sont la perte et la dégradation des habitats, la pollution, la surexploitation (aquaculture non durable et surpêche), l'eutrophisation, le trafic maritime, les espèces exotiques envahissantes, les perturbations humaines, le changement climatique et les prises accessoires. Au Elles sont caractérisées par de petits bateaux artisanaux et des débarquements multi-spécifiques. Une importante pêche industrielle cible principalement les petits pélagiques (essentiellement anchois et sardines) qui sont surtout capturés au moyen de sennes coulissantes et des chaluts pélagiques. Les évaluations des captures sont difficiles en Méditerranée en raison des caractéristiques multi-spécifiques-multi-engins de la plupart de ses activités de pêche, de la dispersion des sites de débarquement et de la faible proportion des captures qui passe généralement par le biais des marchés de poissons organisés. Les pêcheries méditerranéennes sont divisées en quatre sous-zones, dont chacune a ses propres divisions: occidentale, centrale, orientale et la mer Noire.Ils sont principalement capturés en tant que prises accessoires, de bonne valeur commerciale, de pêcheries ciblant surtout des espèces de poissons téléostéens plus productives, comme le thon ou les poissons de fond. Selon les pêcheries, ils sont principalement exploités pour leur chair, ailerons, foie et branchies. Dans certains cas, leur valeur commerciale peut être très élevée (cas des ailerons). Par conséquent, la pression de pêche sur les chondrichthyens est en augmentation.De plus, la plupart des captures de chondrichtyens ne sont pas réglementées et souvent mal identifiées, non enregistrées, agrégées ou rejetées à la mer, ce qui entraîne un manque d'information spécifique concernant les débarquements de ces espèces, et on estime que les captures réelles sont 3 ou 4 fois plus grandes que celles rapportées. Les captures accidentelles et les activités de pêche intensives sont de sévères menaces domaine marin et les changements d'autres variables environnementales peut amener à un déclin des populations des populations de poissons et de leurs biomasses. La présence de chondrichtyens est décrite dans plusieurs zones de la Méditerranée orientale à travers plusieurs études effectuées dans la région.Leur présence dans la partie sud-est de la Méditerranée orientale a notamment ont été mise en évidence par des études menées de la côte nord de l'Égypte jusqu'aux côtes d'Israël.Au Liban, la zone d'étude de la thèse, la pêche libanaise traditionnelle est composée de bateaux de pêche artisanale à petite échelle et les chalutiers sont interdits. La production libanaise d'élasmobranches était de 60 tonnes en 2003 ce qui représente 2% de tous les groupes capturés. distribution dépend en définitive de la productivité primaire de l'écosystème, tandis que la force des interactions biologiques dépend de nombreuses caractéristiques de l'écosystème, y compris la structure physique et la diversité.Les études sur les paramètres du cycle de vie tels que l'âge et la croissance, ainsi que des informations de base sur la répartition, l'abondance, les mouvements, l'alimentation, la reproduction et la génétique, sont essentiels pour les biologistes et écologues afin de comprendre et prédire la manière dont les populations vont grandir et leurs réactions à la pression de pêche.La vulnérabilité des espèces de poissons cartilagineux est liée à la combinaison d'une grande taille maximale corporelle, une croissance lente, une maturité tardive (à une grande taille), et une longue durée de vie. En conséquence, les études sur les traits d'histoire de vie sont indispensables pour la protection, la conservation et la gestion de la pêche de ces grands prédateurs dont le rôle dans l'écosystème est essentiel.

	Chondrichtyens de Méditerranée. La mer Méditerranée contient 80 espèces de chondrichtyens Divers outils de gestion pour les écosystèmes côtiers. Actuellement, au niveau national et
	(près de 7% de l'ensemble des chondrichtyens dans le monde) comprenant 45 espèces de requins international, les politiciens, scientifiques et gestionnaires disposent d'un nombre important
	provenant de 17 familles et 34 espèces de batoïdes issues de 9 familles et une espèce de d'outils pour la gestion des zones côtières et des écosystèmes marins.
	chimères. Elle est identifiée comme l'une des trois régions où la diversité des requins et des raies Au cours des trois dernières décennies, plusieurs conventions importantes ont mis en évidence la Quelques captures d'élasmobranches sont accessoires et certains pêcheurs ciblent quelques est particulièrement gravement menacée. L'Union Internationale pour la Conservation de la nécessité de la conservation des populations d'élasmobranches et de leur gestion à l'échelle espèces commercialement importantes comme la guitare de mer commune Rhinobatos Nature (UICN), a évalué 71 espèces dont 42.25% ont été classées vulnérables et en danger critique d'extinction, 18.31% quasi menacées et pour 25.35% d'entre elles les données sont mondiale et régionale: la convention sur la conservation de la vie sauvage et du milieu naturel rhinobatos (Linnaeus, 1758) et le squale chagrin commun Centrophorus granulosus (Bloch et
	Chondrichtyens. Statut, pêcheries et menaces. insuffisantes. D'autres auteurs ont évalué à 86 le nombre d'espèces d'élasmobranches en mer Schneider, 1801).
	Plusieurs rapports ont été établis reflétant l'état et la conservation des chondrichtyens. Certains
	auteurs ont mené une réflexion sur la conservation des poissons cartilagineux en Méditerranée en
	soulignant le statut d'espèce menacée de plusieurs requins et raies en spécifiant les répercussions
	de la surpêche, notamment celles du marché des ailerons de requin, le problème des prises
	accessoires, de la pollution et de la perte d'habitat sur cette classe de poisson. En 2003, le Centre
	qui affectent de nombreuses espèces marines menacées, telles que les poissons osseux et d'Activités Régionales pour les Aires Spécialement Protégées (CAR / ASP), dans le cadre du
	cartilagineux, les dauphins et les tortues marines. En particulier, la surexploitation des top-Programme des Nations Unies pour l'environnement (PNUE), a créé un plan d'action pour la
	prédateurs, engendrant un changement de biomasse et de composition spécifique, pourrait avoir pour les élasmobranches. conservation des poissons cartilagineux en mer Méditerranée. Ce plan d'action vise à promouvoir espèces marines macroscopiques mondiales dont 25 à 30% sont endémiques. Actuellement, la mer Méditerranée détient 17 000 espèces, soit 7% de toutes les espèces marines connues. Le niveau d'endémisme est particulièrement élevé sur les îles méditerranéennes, où les espèces ont un impact plus important que prévu sur la stabilité des écosystèmes, en particulier marins, que la Aussi, 8 chondrichthyens invasifs originaires de l'Atlantique ou de l'Indo-Pacifique ont été la conservation des populations de Condrichtyens, la protection renforcée de certaines espèces Traits d'histoire de vie des chondrichtyens. Les traits d'histoire de vie sont moulés par suppression d'espèces de plus bas niveaux trophiques. répertoriés en Méditerranée dont 2 ont été observés en Méditerranée orientale. sélectionnées (en voie de disparition), la protection et la restauration des habitats critiques, l'énergie disponible dans l'environnement pour la distribution entre les différents processus
	évolué pour survivre dans des habitats très spécifiques. Cependant, la biodiversité de la l'amélioration des connaissances scientifiques, la reconstitution des stocks épuisés, et les actions biologiques et par les interactions qui influencent les décisions de distribution. L'énergie
	disponible pour la

Chapitre I -Introduction générale. Contexte, problématique et objectifs. La Méditerranée est la plus grande et la plus profonde des mers fermées sur Terre. Elle est reliée à l'océan Atlantique à l'ouest à travers le détroit de Gibraltar et la mer de Marmara et la Mer Noire à l'est à travers le détroit des Dardanelles. Elle a été connectée artificiellement à la mer Rouge et à la région de l'Indo-Pacifique lors de la construction du canal de Suez en 1869. Biodiversité. Méditerranée a été, dans le passé, et sera, dans le futur, continuellement modifiée et modelée par des catastrophes naturelles et anthropiques. Menaces. total, le nombre total d'espèces lessepsiennes marines (envahisseurs via le canal de Suez) s'élève à plus de 790 en mer Méditerranée, dont certaines ayant colonisé avec succès les écosystèmes marins méditerranéens. Une étude récente s'est intéressée à la structure de la population et à la maturité sexuelle du poisson lesseptien Lagocephalus sceleratus dans les eaux libanaises et syriennes, afin de faire la lumière sur la gravité du problème pour cette espèce (Khalaf et al., 2014 -ANNEXE I) dans cette région. En outre, la Méditerranée est également influencée par des espèces introduites à partir de l'océan Atlantique par le détroit de Gibraltar et qui ont atteint la mer Adriatique et même, pour certaines, le bassin oriental. Leur nombre croissant a un impact sur les populations indigènes et peut amener à une réduction de l'abondance des espèces endémiques. En outre, la surexploitation et les prises accessoires sont des problèmes importants Pêcheries. Un peu plus de 1% des débarquements mondiaux proviennent de la pêche en Méditerranée. Les pêcheries méditerranéennes ciblent différentes ressources essentiellement les stocks pélagiques. Aperçu dans le monde entier. Les chondrichthyens ou poissons cartilagineux constituent l'une des familles de vertébrés les plus anciennes et les plus écologiquement diversifiées comprenant les requins, les raies et les chimères. Ils peuvent être présents dans la zone subtidale, bathyale (200-2000 m) et même dans les habitats abyssaux (plus de 2 000 m). La plupart d'entre eux sont des prédateurs de haut niveau trophique, bien que certaines espèces peuvent se spécialiser sur des petits animaux benthiques, comme les polychètes ou les amphipodes. Les poissons cartilagineux sont caractérisés par leurs traits d'histoire de vie conservatifs (longue période de gestation et important investissement maternel, ...). Les trois principales régions où la biodiversité des requins et des raies est particulièrement menacée sont l'Indo-Pacifique, la mer Rouge, et la mer Méditerranée et des actions nationales et internationales sont nécessaires pour les protéger, en particulier, de la surpêche. Méditerranée. La plus forte concentration d'élasmobranches est observée dans les eaux côtières de la Méditerranée occidentale, en particulier dans le bassin nord-occidental, probablement en raison de la nature hautement oligotrophe du bassin oriental. La pêche et les menaces des chondrichtyens de Méditerranée. L'état des poissons cartilagineux en mer Méditerranée est beaucoup plus déplorable que ce qu'il l'est dans le reste du monde: 42% des espèces de requins sont menacées dans cette région contre 17% dans le monde, ce qui fait de la Méditerranée la mer la plus dangereuse au monde pour ces espèces. Les principaux pays pêchant les élasmobranches en Méditerranée sont la Turquie, la Tunisie, la Grèce, l'Italie et l'Espagne et les espèces les plus couramment prises dans les pêcheries côtières méditerranéennes sont: Mustelus spp, Rajids, Scyliorhinus spp, Squalus spp, Myliobatids et Dasyatids. Le changement climatique, dont les effets sont accélérés en Méditerranée, peut également avoir un effet potentiel sur les poissons, en particulier les chondrichtyens. L'augmentation de la température du (Berne, 1979) ; la convention sur les espèces migratrices (Bonn, Novembre 1983) ; le protocole pour les Aires Spécialement Protégées et la Diversité Biologique en Méditerranée (SPA-BD), la convention de Barcelone, (Juin 1995) ; Alimentation des Nations Unies et l'agriculture, le plan d'action international pour la conservation et la gestion des requins (1999 -FAO / PAI-Requins) ; la convention sur le commerce international des espèces menacées d'extinction (CITES, Novembre 2002) ; le programme pour l'Environnement des Nations Unies, le plan d'action pour la Méditerranée pour la conservation des poissons cartilagineux (Novembre 2003). de sensibilisation du public concernant la conservation de cette catégorie de poisson. Les chondrichtyens de Méditerranée orientale. De nombreux requins de poids élevés ou des raies tels que ceux des membres des familles des Hexanchidés, Carcharinidae ou Lamnidae pour les requins et des Dasyatidae et Myliobatididae pour les batoïdes sont souvent observés dans les poissonneries de certaines régions libanaises du nord et du sud du pays. Les poissons capturés sont nettoyés et coupés en filets afin d'être vendus ensuite à des restaurants ou à des clients les achetant au marché avec des prix allant de 4 à 6$ par kilogramme. A partir des recommandations de la "Commission générale des pêches pour la Méditerranée" CGPM /36/2012/3 et de la Convention de Barcelone, le Ministère de l'Agriculture libanais a publié le décret numéro 1/1045 du 13/12/2013, qui établit des normes et des interdictions concernant la pêche ou la vente de certaines espèces de requins et de raies comme le la guitare de mer commune Rhinobatos spp., les requins marteaux Sphyrna spp., et d'autres espèces ciblées dans le commerce.

Acknowledgements

I would like to offer my deepest gratitude to Dr. Eric Clua and Professor Ghassan El Zein who

Acknowledgements

We are particularly grateful to Lebanese fishermen whose catches represent an important part of the collected data. M. Lteif was supported by the Lebanese government through a doctoral grant.

Data and financial support for this study was also partly provided by the scientific survey under the PESCA-LIBANO program performed in the framework of the CANA project of the Lebanese National Council for Scientific Research (CNRS-L).

Acknowledgements

We are particularly grateful to Lebanese fishermen whose catches represent an important part of the collected data. M. Lteif was supported by the Lebanese government through a doctoral grant.

Data and financial support for this study was also partly provided by the scientific survey under the PESCA-LIBANO program performed in the framework of the CANA project of the Lebanese National Council for Scientific Research (CNRS-L).

Acknowledgements

We are particularly grateful to Lebanese fishermen whose catches represent the major part of the collected data. M. Lteif was supported by the Lebanese government through a doctoral grant. Financial support for this study was also partly provided by the scientific survey under the PESCA-LIBANO program performed in the framework of the CANA project --Establishing Monitoring and Sustainable Development of the Lebanese Sea‖ -of the Lebanese National Council for Scientific Research (CNRS-L).

Acknowledgements

We are particularly grateful to Lebanese fishermen whose catches represent a significant part of the collected data. M. Lteif was supported by the Lebanese government through a doctoral grant. Some data and the financial support for this study was also partly provided by the scientific survey under the PESCA-Libano program performed in the framework of the CANA project of the Lebanese National Council for Scientific Research (CNRS-L).

I am indebted to Université de Perpignan Via Domitia (UPVD), especially the directors of the Heussner and Wolfgang Ludwig for welcoming me during my thesis. They offered a very rewarding work environment.

My gratitude also goes to the Lebanese National Council for Scientific Research CNRS-L for granting me a scholarship for a thesis project, as well as hosting me during the course of my thesis in its National Center for Marine Sciences (NCMS) in Batroun.

I offer gratitude to my supervisor Professor Gaby Khalaf and my co-supervisor Dr. sincerest gratitude to Dr. Sherif Jemaa for his nonstop support and help in sampling throughout the course of this thesis. My cordial gratitude also goes to Dr. Mona Ibrahim for her maintained support.

In addition, I would like to thank Stefano Lelli, the coordinator of the PESCA-Libano project which was carried out in the framework of the CANA project of CNRS. His help on the field and

Abstract

The study represents the only evaluation of elasmobranch resources, distribution and diversity along the Lebanese coast, Eastern Mediterranean. It uses cartilaginous fish data from two complementary data collection methods: (a) the CIHEAM PESCA-Libano project carried out with the involvement of the Ministry of Agriculture and the National Center for Marine Sciences -Lebanese National Council for Scientific Research (CNRSL) and (b) fishery and fishermen catch data. Regarding the survey, experimental gillnets, trammel nets and long liners were lowered at depths up to 600 m in 2013. Regarding fisheries and fishermen catch data, cartilaginous fish were collected from major fisheries visited periodically along the Lebanese coast and from the catches of randomly hired fishermen during the same year. The Catch Per Unit Effort (CPUE) was used as an indicator of abundance of the elasmobranchs caught and showed variations in depth, seasonal and spatial distributions. The fishery and fishermen catch data complemented the survey catch data and helped to constitute a wider image of the effect of fishing on elasmobranch species. The spatio-temporal diversity was also reflected and showed highest values in the southern region of the coast and during the spring and winter seasons. This study can be considered as a basis for assessing the threats of fishing operations and inducing sustainable management techniques and possible conservation measures of cartilaginous fish species along the coast of Lebanon.

Keywords

Chapter VII

General discussion, conclusion and perspectives

(IUCN) Red List Category for each species caught. No gear was lowered in winter at depth strata [200-400[and [400-600] and in summer at depth stratum