Researchers Map Long-range Migration of Leatherback Sea Turtles

Ecosphere Leatherback

Large female leatherback turtleat a nesting beach in the Solomon Islands, December 2006.Carapace length is 1.84m. Scott Benson is seated. Photo:Karin A. Forney.

Aninternational team of scientists from NOAA Fisheries Service and severalwestern Pacific research and conservation organizations published a paper todayin the journal Ecosphere that revealshow leatherback turtles use vast areas of the Pacific Ocean and Indo-Pacificseas. The study, based on data from 126 leatherbacks tracked by satellite, ispart of continuing research to understand how oceanographic features influencemigration and foraging behavior of leatherbacks in order to improveconservation efforts for this endangered species.

Leatherbacks (Dermochelys coriacea) are the largest ofall marine turtles weighing up to 2000 pounds (900 kg) and almost six feet (2m) in length. Extensive harvesting of eggs and breeding females by indigenous populations on the nesting beaches along with accidental capture in fisheries has led to the demise of leatherback populations around the Pacific. Some of the last remaining Pacific nesting populations are found in the western Pacific in Indonesia, Solomon Islands and Papua New Guinea.

Female leatherbackslay their eggs on tropical nesting beaches, but then migrate to foraging areasaround the world to feed on jellyfish. Leatherbacks are seasonal visitors tothe central Californiacoast, arriving in late summer and fall to forage on large aggregations ofbrown sea nettles (Chrysaora fuscescens).

Scott Benson, leadauthor of the paper, and senior author Peter Dutton began tracking leatherbacksfrom the California foraging grounds in 2000and expanded the study to the nesting beaches in the western Pacific afterdocumenting that the Californiaturtles were from there. Benson said “We discovered a much greater diversity of foraging behavior than previously thought for Pacific leatherbacks.” The western Pacific nesters foraged not only in distant temperate ecosystems of the North Pacific, but also in temperate and tropical Large Marine Ecosystems (LME’s) of the southern hemisphere and Indo-Pacific seas. Benson said “The foraging areas we identified exhibited a wide range of oceanographic features, including mesoscale eddies, coastal retention areas, current boundaries, or stationary fronts, all of which are known mechanisms for aggregating leatherback prey.

The NOAA FisheriesService has restricted commercial fishing in large areas north of Hawaii and off the United States west coast because of concern over accidental bycatch of leatherbacks, and has proposed designating some areas as critical habitat, said Tomoharu Eguchi, a co-author of the paper. The paper also identifies foraging areas in the East Australia Current Extension and the Tasman Front drawing attention to the potential threat from the intense fishing by international fleets in these waters.

Ricardo Tapilatu ofthe State University of Papua (UNIPA) said “The turtles nesting at Papua Barat(Indonesia), Papua New Guinea,and other islands in our region depend on food resources in waters managed bymany other nations for their survival. It is important to protect leatherbacks in these foraging areas so that our nesting beach conservation efforts can be effective.” Creusa Hitipeuw of World Wildlife Fund for Nature – Indonesia added, “These findings are very useful for the Coral Triangle Initiative in the Western Pacific as one of the goals is to develop and implement a regional action plan to protect leatherback turtles and their habitats".

The combined resultshave fundamentally changed the scope of conservation efforts for Pacificleatherbacks. “Tracking the turtles on their extraordinary migrations over the yearshas allowed us to finally piece together the complex linkages between theirbreeding areas and feeding areas”, said Dutton. “The leatherbacks have acted as international ambassadors and led us to join with many nations and communities on both sides of the Pacific in a concerted effort to conserve this endangered species”.

Read the NOAA Press Release

Read the paper here (scroll down to #art84)

Learnmore about Southwest Fisheries Science Center Marine Turtle Research