Natal origin of loggerhead turtles, Caretta caretta, in the neritic habitat off the Italian coasts, Central Mediterranean

• Published in: Biological conservation 2006, Vol.127 (2), p.183-189
• Main Authors: Maffucci, F., Kooistra, W.H.C.F., Bentivegna, F.
• Format: Article
• Language: English
• Subjects: Amphibia. Reptilia; Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Caretta caretta; Conservation; Conservation, protection and management of environment and wildlife; Fundamental and applied biological sciences. Psychology; Loggerhead turtle; Migration; Mixed stock analysis; Neritic habitat; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 0006-3207; 1873-2917
• DOI: 10.1016/j.biocon.2005.08.009

Shallow (neritic) waters close to the Italian coasts (Central Mediterranean Sea) are frequently visited by foraging loggerhead turtles, but the nesting populations which rely on this area have not been determined. To estimate the rookery origins of this feeding cohort, mitochondrial DNA control region sequences were analysed from 106 juvenile loggerhead turtles and compared to those published for key nesting populations in the Atlantic and Mediterranean regions using a Bayesian based stock analysis program. Six distinct haplotypes were detected, of which two have previously been reported from both Mediterranean and Atlantic nesting beaches and one only from Atlantic nesting populations. The remaining three haplotypes could not be assigned to a rookery of origin. Mixed stock analysis indicated that the waters along the Southern Italian coasts are utilised primarily by Mediterranean nesting populations, with approximately 68% of the individuals provided by the genetically homogeneous Greece/South eastern Mediterranean nesting aggregate and 23% by the Turkish management unit. 7% of the loggerhead turtles were assigned to Atlantic stock. Our results suggest that only a small proportion of the Atlantic juveniles which enter the Mediterranean to forage in its pelagic waters utilise also the neritic areas along the Italian coasts. This is consistent with theory of juvenile homing, according to which oceanic stage juveniles preferentially recruit to neritic developmental habitats within their natal region, and implies that the elevated human-induced mortality occurring in this area impacts almost exclusively the smaller and demographically more vulnerable Mediterranean loggerhead turtle stock.