Origin of leatherbacks (Dermochelys coriacea) found at feeding grounds off the uruguayan coast

VELEZ RUBIO, G.; ; LÓPEZ-MENDILAHARSU, M.;; CARACCIO, M.N.; ; FALLABRINO, A.; ; LA CASELLA, E. ; DUTTON P.H. ; PROSDOCIMI L.,

Las Vegas

Simposio; 37th Annual Symposium on Sea Turtle Biology and Conservation; 2017

International Sea Turtle Society

The leatherback turtle, Dermochelys coriacea, like other species of marine turtles, undertakes long-distance migrations between tropical/subtropical nesting beaches and distant temperate foraging areas. Globally, leatherback status according to IUCN is listed as Vulnerable, but the Southwest Atlantic subpopulation is classified as Critically Endangered (Wallace et al., 2013). The NGO Karumbe has investigated the biology and habitat use of this species in waters off Uruguay for the past 16 years.Satellite telemetry studies have demonstrated that the coastal waters off South America provide important feeding grounds for large juveniles and adult leatherbacks in the western South Atlantic, and ?hotspots? have been identified off Rio de la Plata estuary (Uruguay-Argentina feeding grounds). In the present work we analyzed mitochondrial DNA (mtDNA) variation of leatherbacks sampled at Uruguayan feeding areas in order to determine their nesting beach origin.We estimated the genetic composition of the leatherback foraging aggregation based on analysis of 763 bp sequences of the mtDNA control region in order to determine the nesting origin of these animals. We sequenced a total of 29 samples (8 females, 3 males and 18 indeterminate) collected from large juveniles and adult size leatherbacks (mean 137.4 cm; 118.0 ? 154.0 cm curved carapace length) incidentally captured in fisheries (34.5%) or encountered stranded (65.5%). We identified 5 haplotypes, the most common (n=19) being DC 1.1, followed by Dc 1.3 (n=5), DC 3.1 (n=2), Dc13.1 (n=2) and DC9.1 (n=1).We conducted Bayesian Mixed Stock Analysis (MSA) using data from Dutton et al. (2013) for the key potential source rookery stocks in the Atlantic. Results of the MSA estimates show that the leatherbacks foraging off Uruguay come primarily from the West African rookeries, mainly Gabon and Ghana rookeries (median= 71%; mean =69%, 29% Standard Deviation). Our results are consistent with those obtained in Argentina, with which we share leatherback foraging grounds in the Rio de la Plata estuary. 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. This effort to determine regional stock boundaries and migratory routes is necessary to develop and implement effective conservation measures to mitigate threats both on the nesting beaches and at developmental and foraging areas.