Facteurs de mortalité observés chez les tortues marines dans le golfe de Gascogne

Abstract

Factors of mortality of marine turtles in the Bay of Biscay. Factors of mortality in marine turtles near the French coast of the Bay of Biscay have been recorded for four species: leatherback (Dermochelys coriacea), loggerhead (Car&a carettu), Ridley's turtle (Lepidochelys kempii) and green turtle (Chelonia mydas). Most accidental captures of D. coriacea by fishing gears lead to drowning, but the main threat for the species is the ingestion of floating waste. Plastic bags induce occlusion or lesions in the stomach and subsequent death. For C. car-etta, L. kempii and C. mydas, the pathology points out mainly two features: external or internal mycosis. 0 Elsevier, Paris Chelonian I marine turtle I pathology I pollution / Bay of Biscay RCsumC -L'examen de 230 tortues marines trouvees sur la cbte franqaise du golfe de Gascogne a permis de rechercher les facteurs de mortalite chez quatre especes : Tortue Luth (Dermochelys coriacea), Caouanne (Caretta caretta), Tortue de Kemp (Lepidochelys kempii) et Tortue verte (Chelonia mydas). La noyade consecutive aux captures accidentelles dans les engins de p&he est frequente chez D. coriacea et l'ingestion de dechets flottants presente, a long terme, une grave menace pour l'espece. Les morceaux de plastique provoquent des occlusions ou des lesions infectieuses de l'estomac, dont l'issue est fatale. Chez C. caretta, L. kempii et C. mydas, les lesions dominantes sont celles dues aux mycoses externes et internes.

The leatherback turtle Dermochelys coriacea (Vandelli, 1761) in the bay of Biscay and the North East Atlantic

“…The seasonal pattern of the species in this region was identified by DUGUY (1997) and confirmed by MARTIN (2003). According to these authors, D. coriacea visits the Bay of Biscay during the summer (DUGUY, 1997;MARTIN, 2003;WITT et al, 2007a).…”

“…Bycatch during fishing manoeuvres (DUGUY et al, 1998;LEWISON et al, 2004aLEWISON et al, , 2004bLEWISON & CROWDER, 2007;PECKHAM et al, 2007;BÁEZ et al, 2007 and2008;WA-LLACE et al, 2008), climate change (POLOCZANSKA et al, 2009), the loss of habitat both in egg-laying areas and on the open sea (LUTZ & MUSICK, 1997;BOLTEN & WITHERINGTON, 2003) and sea pollution due to heavy metals and solid residues (DUGUY et al, 1998;MROSOVSKY et al, 2009) are factors responsible for the decline in populations worldwide.…”

“…In the specific case of D. coriacea, mortality factors identified on the French Atlantic coast have been the ingestion of plastics, collision with vessels and bycatch by fisheries (DUGUY, 1997;DUGUY et al, 1998). On the Basque coast and the rest of the Cantabrian coast, although specific studies are inexistent, similar causes of occasional stranding are most likely to be blamed.…”

“…According to these authors, D. coriacea visits the Bay of Biscay during the summer (DUGUY, 1997;MARTIN, 2003;WITT et al, 2007a). Tracking of individuals have shown that turtles migrate from areas of reproduction in the Western Atlantic (Caribbean, French Guiana) to the North Atlantic using northern branches of the Gulf Stream or North Atlantic Current (HAYS et al, 2004ECKERT, 2006;DOYLE, 2007).…”

“…Observation of D. coriacea in the North-East Atlantic tends to be concentrated in the summertime (DUGUY, 1997;MARTIN, 2003;PENROSE & GANDER, 2010). In the case of the Cantabrian coast, there is no established coordinated network of strandings or sightings to help put together information and develop relevant regional coastal reports, as it is the case for the British Isles and France (WITT et al, 2007b;PENROSE & GANDER, 2010;DELL´AMICO & MORINIÈRE, 2010) or in the Mediterranean (e.g.…”