Suivi des observations de tortues marines sur la côte atlantique française depuis 1988

Abstract

Among the seven species of existing sea turtles, four can be seen in the Bay of Biscay and in the Manche. The leatherback turtle Dermochelys coriacea (Vandelli, 1761) and the loggerhead turtle Caretta caretta (Linnaeus, 1758) are the most seen species whereas the Kemp's ridley turtle Lepidochelys kempii (Garman, 1880) and the green turtle Chelonia mydas (Linnaeus, 1758) are seen more occasionally. The monitoring of the sightings done by the Aquarium La Rochelle and its Center of Studies and Cares for Sea Turtles since 1988 allowed us to identify the main characteristics of the sea turtles present on the studied area.KEY WORDS: French Atlantic Coast, Dermochelys coriacea, Caretta caretta, Lepidochelys kempii, Chelonia mydas. RESUMENEntre las siete especies de tortugas marinas que existen, cuatro pueden observarse en el Golfo de Vizcaya y en el Canal de la Mancha. La tortuga laúd Dermochelys coriacea (Vandelli, 1761) y la tortuga boba Caretta caretta (Linnaeus, 1758) son las más frecuentes, mientras que la tortuga lora Lepidochelys kempii (Garman, 1880) y la tortuga verde Chelonia mydas (Linnaeus, 1758) se ven ocasionalmente. El seguimiento de avistamientos llevado a cabo por el Aquarium de La Rochelle y su centro de estudios y cuidado de tortugas marinas desde 1988 nos ha permitido identificar las características de las tortugas presentes en el área de estudio.

Modeling the active dispersal of juvenile leatherback turtles in the North Atlantic Ocean

“…A rapid search of the literature confirms the presence of stranded or bycaught leatherbacks in all main hotspots identified in the active dispersal simulation: in the Azores area [50], off Mauritania [51, 52], along the Portuguese coast [47], in the Gulf of Cadiz [53] and along the Tunisian coast [54]. Stranded or bycaught leatherbacks are also reported in the Bay of Biscay [55], along the Galician coast [56], the Moroccan coast [57], and in the Mediterranean sea [58]. Interestingly, data indicate that leatherback stranding density is markedly higher along the Portuguese coast than in the bay of Biscay or Galicia [47].…”

Ecological Trap or Favorable Habitat? First Evidence That Immature Sea Turtles May Survive at Their Range-Limits in the North-East Atlantic

“…These sightings gather individuals stranded, bycaught in fishing nets or drifting at sea. Initiated in 1988 and compiling data from the four species found along Western Europe (leatherback, loggerhead, Kemp's ridley and green), this dataset has been partly published (Witt et al, 2007;Morinière and Dell'Amico, 2011). To be consistent with the tracking analysis, we restricted this dataset to the three species satellite tracked in our study, i.e., the loggerhead, the Kemp's ridley and the green turtle.…”

“…Stranding events of sea turtles occur annually along the Western European coasts, including the Spanish (Bellido et al, 2010;Orós et al, 2016), Portuguese (Nicolau et al, 2016), British (Botterell et al, 2020) and French coasts (Witt et al, 2007;Morinière and Dell'Amico, 2011). Genetic analysis have demonstrated that immature loggerhead turtles stranded along the French Atlantic and English Channel coasts mostly originate from the North-East American coast (51%), and to a lesser extent to Cape Verde (26%) (Monzón-Argüello et al, 2012).…”

“…Hatchlings emerging from Florida rookeries are known to perform a transatlantic oceanic migration toward several developmental habitats located in the Azores, Madeira, Cape Verde, and Canary Islands (Bolten et al, 1998). But despite the large number of stranding events observed each year (Witt et al, 2007;Bellido et al, 2010;Morinière and Dell'Amico, 2011;Nicolau et al, 2016;Orós et al, 2016;Botterell et al, 2020), no favorable developmental habitat has been identified yet along the continental European coast due to potentially unfavorable thermal conditions and the high latitudinal location of this areas, assumed to be outside the species usual range (Wallace et al, 2010). In addition to loggerhead turtles, green (Chelonia mydas) and Kemp's ridley sea turtles (Lepidochelys kempii) originating from North-West Atlantic, Caribbean, and Gulf of Mexico (Manzella et al, 1988;Marquez, 2001;Wallace et al, 2010) are, two species rarely seen in European waters, annually gathering in lower proportions along the French Atlantic coast and English Channel coasts.…”

“…In 2010, Wallace et al (2010) delineated 58 Regional Management Units (RMUs) based on published satellite tracks, tag returns and demographic and genetic data collected from nesting populations for the seven sea turtle species worldwide. However, these units have not incorporated some sites of immature turtle aggregation, in particular in the North-East Atlantic where immature loggerheads, greens and Kemp's ridleys are frequently observed (Bellido et al, 2010;Morinière and Dell'Amico, 2011;Monzón-Argüello et al, 2012;Nicolau et al, 2016;Orós et al, 2016;Botterell et al, 2020). Satellite tracks and stranding reports collected from European waters therefore provide a unique source of data to update these RMUs and design more appropriate units of protection taking into account juvenile sea turtle habitats.…”