Satellite-tracking Reveals Multiple Foraging Strategies and Threats for Olive ridley Turtles in Brazil

Abstract

The state of Sergipe in northeastern Brazil is the largest nesting area for olive ridley turtles along this nation’s coast, and constitutes a major rookery in the western Atlantic as well. Conservation efforts with a focus on nesting activities have been implemented there since 1982, but little is known about other aspects of the life cycle, specifically post-nesting movements of females and the locations of foraging grounds. To address this issue, satellite transmitters were deployed on 10 females that nested between February and April 2006. The turtles were monitored for an average of 113 d (range: 14 to 297 d), and an average movement of 1669 km (range: 407 to 4265 km) was recorded. Of the 10 turtles monitored, 6 moved along the Brazilian continental shelf to neritic foraging areas. Five of these turtles utilized foraging areas along the northern and northeastern coasts of Brazil, while one foraged along the southeastern coastline. Two females were tracked to equatorial oceanic waters, with one first moving to an inshore foraging site where she remained for 34 d before migrating to oceanic waters off the Brazilian coast. Signal transmission of 3 of the 10 turtles tracked ceased during their post-nesting migrations, preventing identification of their feeding areas. Olive ridley turtles nesting on the coast of Sergipe displayed a range of post-nesting movements including to coastal sites along the continental shelf as well as offshore oceanic areas. Inter-nesting habitats, migration routes and foraging grounds showed great overlap with a variety of coastal fisheries, as well as with longline fishing in oceanic waters, a key consideration for developing conservation strategies for this species in the western Atlantic.