Study tracks turtles' journey across South Atlantic

[January 05, 2011]  LONDON (AP) -- Leatherback turtles swim for thousands of miles across the South Atlantic to get to their feeding grounds, a trip that takes some of them 150 days to complete, researchers said Wednesday.

The findings are important for conservationists looking to protect the turtles from threats such as fishing nets and hooks, which have been blamed for the dramatically depleted population of leatherbacks in the Pacific Ocean, researchers said.

"All of the routes we've identified take the leatherbacks through areas of high risk from fisheries, so there's a very real danger to the Atlantic population," said Brendan Godley, a professor in conservation biology at the University of Exeter.

The five-year study followed the movement of female turtles from the world's largest breeding colony in Gabon, central Africa, as they swam to feeding grounds across the South Atlantic. Once the turtles reach a food-rich habitat, they will stay there for up to five years to build up reserves to reproduce and return to Gabon once they are ready to mate again.

Researchers attached electronic satellite tracking equipment to the backs of 25 female turtles, as they finished nesting on beaches and were returning to the sea.

One female was tracked making a 7,563 kilometer (4,699 mile) journey traveling in a straight line across the South Atlantic from Africa to South America, said Matthew Witt, a marine biologist who took part in the study. At a pace of 50 kilometers a day, that trip took about 150 days of consistent swimming, he said.

"Despite extensive research carried out on leatherbacks, no one has really been sure about the journeys they take in the South Atlantic until now," Witt said. "From a human perspective, the South Atlantic is a vast, vast area. When challenged with that path, how is it that you can get across it and not get lost? I think that's fantastic."

The study identified three migratory routes, taking the turtles from Central Africa to Brazil, Uruguay, Argentina and down the coast of southern Africa. But why individual turtles choose one route over another remains one of the biggest questions in sea turtle biology, Witt said.

There are more leatherback turtles in the Atlantic than in the Pacific, where populations have declined dramatically over the past three decades. The exact cause of the dwindling numbers is not clear, although turtle egg harvesting, coastal net fishing and longline fishing have been blamed.

Witt said that the study helped identify 11 nations in the South Atlantic whose territorial waters the turtles pass through, and that those countries could take the lead on marine conservation efforts.

The research was published in the Proceedings of the Royal Society B on Wednesday.

[Associated Press; By SYLVIA HUI]

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