Leatherback turtles on verge of extinction

Researchers see a bleak future for leatherback sea turtles unless protective measures are implemented and soon

June 1, 2000
Web posted at: 12:59 p.m. EDT (1659 GMT)

By Environmental News Network staff

The thousands of surfers who regularly flock to Tamarindo, Costa Rica, to ride the break at Henry's Point may soon have no reason to take a nighttime side trip to view leatherback sea turtles at nearby Playa Grande.

The turtle colony that nests on this crescent-shaped, white-sand beach will decline to an unrecoverable low of 50 nesting females by 2003 to 2004 unless protective measures are taken immediately, researchers report in today's Nature.

"The leatherback has outlasted dinosaurs, has outlasted all sorts of catastrophes," said Pamela Plotkin, a conservation scientist at the Center for Marine Conservation in Washington, D.C., and co-author of the research. "Now, at the hands of man, it is right on the brink of extinction."

The most probable cause for the turtles' eminent extinction is mortality from gill-net and longline swordfish and tuna fisheries. The creatures, which can grow as long as 9 feet and weigh more than 2,000 pounds, get tangled in the nets and hooked by the longlines.

To save the turtles, humans must close areas of ocean to fishing where the turtles congregate, get rid of all gill nets and require all countries to use turtle-excluder devices, said James Spotila, an environmental scientist at Drexel University in Philadelphia, Pennsylvania.

"The only effect this is going to have is to make fish more expensive," said Spotila, lead author of the Nature paper. "It makes no difference if you sell 10 fish for $100 or 100 fish for $10. Most of these fish are not being eaten by poor people."

An aerial view of two beaches in Costa Rica where research was conducted on leatherback sea turtle colonies

Spotila and colleagues have studied leatherbacks at Playa Grande since 1988. The colony there is the fourth largest in the world. Since 1993 the researchers have permanently marked females by injecting them with passive integrated transponders — pin-needle-sized devices that deliver a number when contacted by a radio wave.

From July 1988 to June 1989 the researchers counted 1,367 nesting females. They counted only 117 in 1998-1999. According to a mathematical model based on their survey, the researchers predict that there will be less than 50 nesting females by 2003-2004.

In February 1999, the Center for Marine Conservation filed a lawsuit in Hawaii to force the National Marine Fisheries Service to protect the leatherback turtle from longline fisheries.

In November 1999, a judge ordered the fisheries service to draft an environmental impact statement analyzing the impact of longline fisheries on turtles. In the meantime, he closed thousands of square miles in the Pacific Ocean to the Hawaii-based longline operation.

In the next few weeks, the judge is expected to enlarge the area he closed based on recommendations from the fisheries service and conservation groups.

According to preliminary reports, said Plotkin, the fisheries service is recommending measures that would reduce the leatherback take by longliners by 45 percent. She said conservation groups are pushing for more — a reduction of 75 percent.

"We are confident that when the article (in Nature) comes out, the judge will decide in our favor," she said. "However, in terms of recovering the population, I am not optimistic. It is such a broad problem that involves so many countries."

Copyright 1999, Environmental News Network, All Rights Reserved

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Nature
James Spotila
Center for Marine Conservation
National Marine Fisheries Service
The Leatherback Taskforce
The Monterey Bay Whale Watch

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