Western Pacific leatherback sea turtle populations have declined 83% over the last five decades and are considered Critically Endangered according to IUCN. Protection of the remaining leatherback sea turtles in the Western Pacific is essential for population recovery, and this protection needs to extend to in-water habitats, where turtles spend the vast portion of their lives. But the protection of leatherback turtles at sea requires first-hand knowledge of their distribution in time and space, thus determining at-sea distributions and threats is essential for leatherback protection, restoration, and management.
Leatherback turtles are known to congregate off Palawan year-round, with distributional shifts between the Sulu and South China Seas, and between the northwest coast of Palawan and Balabac. The goal of the current project is further investigate this leatherback assemblage using aerial surveys to increase our understanding of the spatial and temporal residence patterns for leatherbacks in the South China / Sulu seas.
Approximately quarterly surveys are conducted using a Britten-Norman Islander to document leatherback turtles, along with other forms of large marine life and fishing effort. Each survey expedition consists of three flights off the coast of Palawan, Philippines. Flights typically last four to five and a half hours with transits of roughly 40 minutes to and from the survey areas. One flight is conducted to the NW of Palawan off the coast of El Nido; a second flight is conducted to the southwest, off the coast of Balabac Island, and the third flight is conducted to the northeast, east of Tay Tay, and south of Coron / Busuanga.
We have been able to document leatherback turtles on nearly all flights, along with green turtles, dolphins (primarily Indo-Pacific Humpback and Spinners, and Indo-Pacific Bottlenose), dugongs, a Bryde’s whale, several manta rays, and numerous fishing vessels of varying sizes and types. and numerous fishing vessels of varying sizes and types. Primary types of fishing vessels include small (2-4m in length) bancas, large bancas (10-12m in length) and large purse seine vessels. No foreign fishing boats were detected on any of the surveys which might have indicated the presence of turtle poachers.
We have recorded a substantial overlap between green turtle distribution and fishing vessels during the April/May around Tay-Tay, and an overlap between leatherback turtles and longline/purse seine fishers to the east of Dumaran Island which warrant further investigation.
The project has been funded via NOAA-PIRO Grants and a Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) Philippines Grant, along with a contract by the US NMFS SOuthewest Fisheries Science Center; and implemented by the Marine Research Foundation in collaboration with the NOAA Southwest Fisheries Science Center, the Philippines Biodiversity Management Bureau (formerly the Protected Areas and Wildlife Bureau), and the Palawan Council for Sustainable Development (PCSD).
