Scientists are using GPS devices to track highly endangered leatherback turtles in the Pacific to determine where and when they face the largest risk of being caught and killed by longline fishing boats.

The scientists are proposing that the fisheres be closed in those areas when leatherbacks are present.

The study, which tracked 135 adult turtles, was published Wednesday in the journal Proceedings of the Royal Society B.

"Leatherback turtles get caught on longlines by both biting at the bait and getting entangled in the lines themselves," said James Spotila, a research team member and professor of environmental science at Drexel University in Philadelphia. "Fishermen do not want to catch the turtles but have had limited success in avoiding them. Now they will be able to set their lines in areas where the turtles are unlikely to occur, making the ocean safer for turtles and reducing the cost to the fishermen of having to deal with the giant turtles."

The research on "bycatch" risk was conducted by a team from Drexel, several other universities, the federal Southwest Fisheries Science Center and a U.S. nonprofit organization, the Leatherback Trust.

The study found the greatest risk was in two areas.

In the western Pacific, it’s adjacent to nesting beaches in Indo-Pacific islands such as Papua New Guinea,  Irian Jaya and the Solomon Islands. These areas are under the exclusive economic control of national authorities and can readily be regulated, the scientists said.

In the western Pacific, the greatest risk is in a system of currents called the South Pacific Gyre, a broad open ocean area outside national waters. Management is currently lacking for this area and may be difficult to implement, the authors said.

 The leatherback turtle in the Pacific Ocean is one of the most endangered animals in the world. Its population has declined by more than 90 percent since 1980, scientists say.

According to the World Wildlife Fund, as few as 2,300 adult females remain.