Satellite Tracking Of Leatherback Turtles From Caribbean Central America Reveals Unexpected Foraging Grounds

Satellite Tracking Of Leatherback Turtles From Caribbean Central America Reveals Unexpected Foraging Grounds

Daniel R. Evans1, Cristina Ordoñ ez2, Sebastian Troëng3, and Carlos Drews4
1 Caribbean Conservation Corporation, 4424 NW 13th Street, Ste B11, Gainesville, FL 32609, USA
2 Caribbean Conservation Corporation, Bocas del Toro, Panama
3 Conservation International, 1919 M Street NW, Washington, DC 20036, USA
4 World Wildlife Fund, San José , Costa Rica

From 2003-2006, the Caribbean Conservation Corporation has tracked 12 adult female leatherbacks from nesting beaches located along the Caribbean coast of Costa Rica (Tortuguero & Gandoca) and Panama (Chiriquí Beach). Eight of the transmitters were KiwiSats 101 supplied by SirTrack and four were Series 9000x SRDLs produced by the Sea Mammal Research Unit. All PTTs were attached dorsally to the female turtles during nesting using a custom-fitted harness made of nylon webbing and polyvinyl tubing, and designed to be released within approximately two years. Tracking duration ranged from 23 days to 443 days, with an average of 185 days. The KiwiSats had an average duration of 159 days, while the SDLRs sent information for an average of 238 days. One SRDL unit continues to transmit data after 120 days (transmitter was deployed on June 16, 2006).

Nine of the 12 tracks provided sufficient tracking data to establish a migratory route out of the Caribbean and were extensive enough to suggest possible foraging areas. Of these, four were tracked to the Gulf of Mexico by traveling between the western tip of Cuba and the Yucatan Peninsula of Mexico. The remaining five leatherback turtles were tracked traveling from the Caribbean Sea into the northern Atlantic Ocean, either through the passage between Cuba and Haiti (2) or the passage between the Dominican Republic and Puerto Rico (3). Within the Gulf of Mexico, three leatherbacks stayed within the eastern part of the Gulf off of the coasts of Florida and Alabama, while the forth is currently in the western Gulf of Mexico. The leatherbacks reaching the North Atlantic Ocean either stayed close to the Atlantic coast of North America (2), traveled near Bermuda (2) until reaching the waters off of Nova Scotia, Canada, or traveled straight across the North Atlantic Ocean to waters north of the Azores Islands.

There have been recorded sightings of leatherbacks throughout the Gulf of Mexico, in both near shore and offshore waters, as well as flipper tag recoveries from females tagged on nesting beaches in Caribbean Central America. Our tracking research indicates that these animals may be foraging rather than just migrating through the Gulf of Mexico. We conclude that the Gulf of Mexico may represent a significant foraging ground for leatherbacks from the Caribbean coast of Central America. While jellyfish populations in the Gulf of Mexico have been increasing for over a decade, the summer of 2000 saw a population explosion of both native and invasive jellies. Although it is not possible to determine from our study, the increased occurrence of sightings and the movements of leatherback turtles in the Gulf of Mexico could be related to the increase in available prey items associated with the growth in jellyfish abundance. There is also the possibility that leatherback by-catch in fisheries in the Gulf of Mexico could be contributing to the slight decline in nests observed on index nesting beaches in Caribbean Costa Rica.

Abstract of paper presented at 27th International Symposium, 2007