for National Geographic News
They are the longest-living marine species to ever ply the world's oceans. They survived catastrophic asteroid impacts and outlived the dinosaurs. But the leatherback sea turtle, the largest turtle in the world, is on the brink of extinction, and scientists question whether the animal will survive into the next decade.
"Over the last 22 years their numbers have declined in excess of 95 percent," said Larry Crowder, a marine scientist at Duke University in Durham, North Carolina. Crowder detailed the plight of the turtle during last week's annual meeting of the American Association for the Advancement of Science in Denver, Colorado.
Leatherback turtles roam tropical and sub-tropical waters of the Pacific, Atlantic, and Indian Oceans. They are found as far north as the British Isles to as far south as Australia. The turtles grow as large as nine feet (2.7 meters) long, six feet (1.8 meters) wide and weigh over 1,000 pounds (454 kilograms). Leatherback turtles are covered in a namesake rubbery shell and can dive 4,922 feet (1,500 meters) deep in search of soft-bodied prey like jellyfish.
Leatherback sea turtles have lived for 150 million years. If the species is allowed to vanish, scientists believe it will foreshadow the extinction of a host of other marine species. Scientists estimate there are less than 5,000 nesting female leatherbacks in the Pacific Ocean today, down from 91,000 in 1980.
Crowder has joined more than 400 international scientistsincluding marine biologist and National Geographic Society Explorer-in-Residence Sylvia Earlein calling on the United Nations to issue a moratorium on destructive fishing practices in order to save the turtle.
"Recent studies warn that unless immediate and significant steps are taken, the world's largest and most wide-ranging sea turtle will soon become extinct," signatory scientists said in a statement issued last week in advance of a meeting by UN's Food and Agriculture Organization's Committee on Fisheries which begins today in Rome, Italy.
Hooked, Tangled, Harvested
Leatherback sea turtle populations have been decimated by a fishing technique known as longlining, in which fishing vessels lay out 40- to 60-mile-long (64- to 97-kilometer) lines of vertically hanging baited hooks.
"An individual vessel will put out 3,000 hooks at a time. It is a curtain of baited hooks," said Todd Steiner, director of the Save the Leatherback Campaign for the Sea Turtle Restoration Project in San Francisco, California.
Leatherback sea turtles get caught up and tangled in these hooks, causing them to drown. Scientists are uncertain as to what attracts the leatherbacks to the hooks, which are used primarily to catch swordfish and tuna.
According to a recent study conducted by the Pew Charitable Trusts (a non-profit philanthropic organization based in Washington, D.C. and Philadelphia, Pennsylvania), longline fishing fleets set on the order of 1.5 billion baited hooks in the world's oceans each year. "That's 4.5 million hooks per night," said Crowder. A number, he adds, which is too high to sustain.
To help remedy this problem, U.S. longline fisheries already have been restricted or closed in areas where leatherback sea turtles are known to swim. But scientists believe that this will not be enough to save the leatherbacks from extinction.
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