All seven species of sea turtles are considered critically endangered by the World Conservation Union, but the precarious plight of the leatherback, the oldest and largest species, has conservationists especially alarmed. Karen Steele of the Sea Turtle Restoration Project says that the population has plummeted by over 95 percent, from 115,000 in 1980 to less than 3,000 nesting females in 2006. Steele worries that the big turtles may be only 5 to 30 years away from extinction.
Yet NOAA Fisheries is now considering a rollback of restrictions along the California and Oregon coast on fishing practices that catch and kill leatherbacks—drift gillnet and long-line fishing. Says Steele, “The reasons given are that there aren’t as many sea turtles there as they thought, and that the restrictions affect the fishing industry adversely by limiting their catch.” Many scientists—including Steele—vehemently oppose any rollback, pointing out that the small number of turtles now in residence simply reflects their dwindling numbers globally. They say that the fishing industry has declined so much along the coast that it would gain next to nothing from the rollback, but the change could push the turtles over the edge to extinction.
Known as “the dinosaurs of the sea,” leatherbacks have been around for 100 million years, since before the time of Tyrannosaurus rex and friends. Picture a turtle the size of a table for eight swimming 22 mph and capable of diving down to 3,900 feet. The only shell-less turtle, they’re named for their tough, leathery skin, which forms seven ridges along their backs. Because of their body’s low surface area to volume and thick, insulating fat, they are the only warm-blooded reptiles. “They are amazing animals,” concludes Steele.
Leatherbacks have been spotted as far north as Alaska and as far south as Chile, says Steele. It’s not uncommon for them to migrate 10,000 miles in a year or to cross an entire ocean basin, searching for nesting beaches and foraging for jellyfish. Moon jellyfish, with bells the size of dinner plates, are the turtles’ favorites, and it takes about 50 a day to satisfy a leatherback.
“They spend their entire lives—and they can live to be 100—in the water,” says Steele. “Nesting is the only activity that draws them out.” The eastern leatherback population nests on beaches in Costa Rica, Mexico, and Nicaragua, while the western population nests in Indonesia, New Guinea, and Malaysia. Mating every two to three years, leatherbacks may lay up to 12 times at 10-day intervals in one season, for a total of 450 to 600 eggs. The nesting female clears a site using her front flippers like shovels, then digs a few feet down into the moist sand with her rear flippers before depositing her eggs and carefully filling in the hole. Hatchlings tunnel up through the sand, usually emerging after dusk, then scramble towards the water, attracted by moonlight reflected in the waves.
In late summer and fall, leatherbacks in search of jellyfish are spotted off the California coast between Monterey Bay and Oregon, says Steele. Satellite tracking shows that they migrate in from western Pacific nesting beaches, like those of Papua Indonesia. “This year turtles have been seen north of the Golden Gate in the waters off Marin County—but in much smaller numbers than two decades ago,” she says.
Leatherbacks face many threats, but chief among them are humans harvesting the eggs from nesting beaches and drift gillnet and long-line fishing. Drift gillnets, often a million square feet in size, are placed vertically like curtains to drift with the current and ensnare large fish. Long-line fisheries catch fish and sometimes turtles with 60-mile lines of baited hooks. Other hazards are plastic bottles and bags that leatherbacks may confuse with jellyfish, and developments near nesting beaches which, when lit up at night, draw hatchlings away from the water. Development of major nesting beaches around the Pacific has forced the population out to fewer, more far-flung areas.
“Conservationists have worked with western Pacific villagers to protect the turtle eggs, but that’s hard,” says Steele, “because the eggs have been important in the local economies, as well as a diet staple.” Steele says the approach in the US has been to set up a Leatherback Conservation Area in the 200-mile-wide Exclusive Economic Zone (EEZ) between Monterey Bay and the mid-Oregon coast and to restrict drift gillnet fishing there from August 15 to November 15, when the leatherbacks tend to show up. This restriction was implemented in 2001 after a biological opinion was issued by NOAA Fisheries Service. In 2004, long-line fishing was restricted in the same way.
“These measures have been effective,” notes Steele. “There has not been one sea turtle capture since 2001.” If the restrictions are rolled back, drift gillnet vessels might be allowed in the EEZ during the critical period but would be required to have an observer on board at all times who would report any sea turtle captures. The vessels would have to move out of the critical area after two sea turtle captures in one season.
Some fear that this measure could lead to elimination of the Leatherback Conservation Area, with the result that only 20 percent of drift gillnet vessels would be required to carry an observer. Says Steele, “For now, we are urging the public to contact NOAA Fisheries Service and ask them to keep the existing restrictions in place.” With leatherbacks near the brink, this is no time to give up.
Contact:
Write letters to William Hogarth, Director, NOAA Fisheries Service, 1315 East West Highway, SMC3; Silver Springs, MD 20910
Or call or email (301) 713-2379; Bill.hogarth@noaa.gov
