Evidence of migratory movements of olive ridley turtles (Lepidochelys olivacea) along the Brazilian coast

Abstract

Projeto Aves, Quelonios e Mamiferos Marinhos da Bacia de Campos, Grupo de Estudos de Mamiferos Marinhos da Regiao dos Lagos (GEMM-Lagos) / Oceanites, Departamento de Endemias, Escola Nacional de Saude Publica, FIOCRUZ (Rua Leopoldo Bulhoes, 1480 - 6o andar - Sala 620, 21041-210 Rio de Janeiro, RJ, Brasil) *Corresponding author: est.cardinot@gmail.com Sea turtles have a long and complex life cycle involving transoceanic migrations and marked changes in diet and habitat. Juveniles are believed to spend their first few years drifting passively in ocean current systems or on floating sargassum rafts (CARR, 1986; BOLTEN et al., 1998). Advanced juveniles subsequently shift to coastal feeding habitats (CARR, 1987). After reaching sexual maturity, some 20 or 30 years later (FRAZER; EHRHART, 1985; KLINGER; MUSICK, 1995), adults undertake reproductive migrations that range from tens to thousands of kilometers (MEYLAN, 1982; MEYLAN et al., 1983; HUGHES, 1989; LIMPUS et al., 1992). Nesting usually occurs in spring and summer. Tagging data suggest that sea turtles show maternal philopatry to their natal site (BJORNDAL et al., 1983; BOWEN et al., 1993). Five sea turtle species can be found in Brazil: Caretta caretta, Chelonia mydas, Eretmochelys imbricata, and Lepidochelys olivacea of the Cheloniidae family, and Dermochelys coriacea of the Dermochelyidae family (MARCOVALDI; MARCOVALDI, 1999) . L. olivacea (Eschscholtz 1829), known as olive ridley turtle, shows a great concentration of nests in Sergipe and northern Bahia states, on the north-eastern Brazilian coast (DA SILVA et al., 2007). Also, based on incidental catch by the Brazilian pelagic longline fishery, Sales et al. (2008) have suggested that the offshore waters of the north-eastern Brazilian coast are a preferential habitat for olive ridley turtles. Under the International Union for Conservation of Nature criteria, this species is currently considered endangered (IUCN Red List of Threatened Species, available at , December 2009). In addition, L. olivacea is listed in Appendix I of the Convention on International Trade in Endangered Species of Fauna and Flora (available at , December 2009). Here we discuss the possible existence of a translocation pattern of olive ridleys along the Brazilian coast based on reports of specimens stranded along the central-north coast of Rio de Janeiro state since 2005. These reports include an olive ridley tagged by the TAMAR Project in Sergipe and found by our research group in Quissama, northern Rio de Janeiro state. Since 2005, GEMM-Lagos / Oceanites staff has been regularly monitoring beaches along the central-north coast of Rio de Janeiro state, from Saquarema (22