Scientia Marina, Vol 72, No 3 (2008)

Tagging reveals limited exchange of immature loggerhead sea turtles (Caretta caretta) between regions in the western Mediterranean

Mónica Revelles
Department of Animal Biology, Faculty of Biology, University of Barcelona, Spain

Juan Antonio Camiñas
Instituto Español de Oceanografía (IEO), Centro Oceanográfico de Málaga, Spain

Luis Cardona
Department of Animal Biology, Faculty of Biology, University of Barcelona, Spain

Mariluz Parga
Marine Animal Rescue Center (CRAM), Spain

Jesús Tomás
Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain

Alex Aguilar
Department of Animal Biology, Faculty of Biology, University of Barcelona, Spain

Ferran Alegre
Marine Animal Rescue Center (CRAM), Spain

Antonio Raga
Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Spain

Albert Bertolero
Laboratoire de Biogéographie et Ecologie des Vertébrés, EPHE University of Montpellier, France

Guy Oliver
Réseau Tortues marines de Méditerranée française, Laboratoire de Biophysique et Dynamique des Systèmes intégrés, University of Perpignan, France


Exchange of immature loggerhead sea turtles (Caretta caretta) between the northern and southern regions of the western Mediterranean was investigated using data obtained from several Spanish tagging programmes. Tagged turtles ranged in straight carapace length from 23.0 to 74.0 cm. Thirty-six turtles were recaptured after an average interval of 390.5±462.6 days (SD). As the mean dispersal distance (MDD) of a turtle population that spreads over the western Mediterranean would stabilize after 117 days (CI 95%: 98 to 149), two analyses were conducted that included data from turtles recaptured after 98 and 149 days respectively. In both analyses, turtles were recaptured more often than expected in the same region where they had been tagged. No difference was found in either of the two regions between the average distance between the capture and recapture locations and the expected MDD if the turtles were to remain in the region where they were first captured. Turtles recaptured after 15 and 25 days respectively were excluded from the analysis to ensure data independence. The overall evidence indicates that immature turtles exhibit strong site fidelity to certain areas and that there is a strong barrier to dispersal between the northern and southern parts of the western Mediterranean. Therefore, loggerhead turtles in the western Mediterranean should be split into at least two management units.


biogeography; loggerhead sea turtle; capture-mark-recapture; flipper tags; dispersal; Mediterranean

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