Genetic stock origin of leatherbacks (Dermochelys coriacea) found at feeding grounds off the Argentine coast

PROSDOCIMI L.; DUTTON P.H.; ALBAREDA D.A.; RODRIGUEZ-HEREDIA S.; BRUNO I.; REMIS M. I

Huatulco

Congreso; 32nd Annual Symposium on Sea Turtle Biology & Conservation; 2012

The leatherback turtle, Dermochelys coriacea, like other species of marine turtles, is known to undertake long migrations between tropical nesting beaches and distant temperate foraging areas. Since 2003, the Regional Program for Sea Turtle Research in Conservation of Argentina (PRICTMA), has investigated the status and habitat use of these endangered species of reptiles the coastal waters off Argentina. Satellite telemetry studies have demonstrated that the coastal waters off South America provide important feeding grounds for leatherbacks in the western South Atlantic, and ?hotspots? have been identified off Argentina, although there is no nesting documented south of Brazil. In the present work we analyzed mitochondrial DNA (mtDNA) variation of leatherbacks sampled at feeding areas off Argentina in order to determine their nesting stock origin. A 711 bp fragment of the mtDNA control region was sequenced using primers LCM 15382 and H950 (Abreu-Gobrois et al. 2006) and aligned to an unpublished reference dataset (Dutton et al. unpublished data). We sequenced a total of 26 samples (16 females, 9 males and 15 indeterminate) collected from adult leatherbacks (mean 146.3; 148.5 ? 141.1 cm curved carapace length) captured (10%) in fisheries or encountered as strandings (90%).  We identified 3 haplotypes, the most common (n=21) being DC 1.1, and the other two rarer DC 1.3 (n=4) and DC13.1 (n=1). The genetic diversity was evaluated through the haplotype (0.3354 +/-0.1060) and nucleotide diversities (0.000456 +/-     0.000515). We conducted Bayesian Mixed Stock Analysis (MSA) using unpublished data from Dutton et al. (in prep) for the key potential source rookery stocks in the Atlantic.  Results of the MSA estimates show that the Argentina foraging leatherbacks come primarily from the West African rookeries (mean estimate=82%, 40.9 - 99.7%, 95% confidence interval) as opposed to Caribbean and western Atlantic rookeries.  Our results are consistent with those from mark-recapture studies, since four leatherbacks captured in Argentinean waters were adult females that were originally tagged on the nesting beaches in Gabon, West Africa.  Taken together these findings reinforce our understanding of the connectivity between these breeding and foraging areas on opposite sides of the ocean in the South Atlantic.  These genetic results provide new information to link nesting and foraging areas in the South Atlantic and are part of a broader effort to determine regional stock boundaries and migratory routes in order to develop and implement effective conservation measures to mitigate threats both on the nesting beaches and at developmental and foraging areas.