Satellite tracking of hawksbill turtles Eretmochelys imbricata nesting in northern Bahia, Brazil: turtle movements and foraging destinations

摘要

Data on hawksbill Eretmochelys imbricata migratory patterns are virtually unknown for nesting populations in the South Atlantic Ocean. The most significant nesting ground for hawksbills in the South Atlantic is located in Brazil,specifically in the northern state of Bahia.From February to March 2005,15 adult female hawksbills were equipped with satellite transmitters on beaches of northern Bahia. During the internesting period,satellite-tracked hawksbills remained in the coastal waters of northern Bahia for 12 to 60 d before embarking on their postnesting migrations.Internesting areas occupied by the turtles varied between 43.1 and 447.9 km~2.Turtles' postnesting migrations were performed mostly over the continental shelf: 5 headed south,and 8, north.Results from genetic analyses of tracked turtles showed that 6 of the individuals,characterized morphologically as hawksbills,were actually hawksbill-loggerhead hybrids.Foraging destinations of hawksbills were situated along the eastern coast of Brazil (9 to 17.5°S).Conversely,except for 1 hybrid that stayed along the eastern coast, hybrid turtles migrated to distant foraging areas located on the northern coast of Brazil (0 to 5°S). Foraging home range areas of satellite-tracked turtles ranged from 225.7 to 2192.3 km~2,and there were no significant differences in size between areas used by hawksbills and those used by hybrids.The location of hawksbill foraging areas partially overlapped with established marine protected areas (MPAs) distributed along the main reef areas in Brazil.These results underscore the importance of strengthening MPA monitoring and enforcement to protect critical hawksbill habitats in Brazil.