It weighs a ton and it has outlived the dinosaurs by 65-million years. But the leatherback sea turtle — one of the largest, oldest and widest-ranging marine animals ever to cruise the oceans — could be heading for extinction.
Leatherbacks have become the world’s most endangered sea turtle. The creatures, which can measure up to 2,7-metres long and 1,8-metres wide, are caught by gill nets and longlines at sea, their eggs are raided on land and their nesting habitat is being destroyed.
”They survived over 100-million years, through climate change and asteroid impacts, but they could become extinct in 10 to 20 years unless sufficient international cooperation is mounted to reverse this dramatic decline,” Larry Crowder of Duke University, North Carolina, told the American Association for the Advancement of Science conference in Denver, Colorado. ”There are probably fewer than 1 500 females nesting throughout the Pacific rim.”
In the rainforests and the savannahs, and in mangrove swamps and coral reefs, wild things are threatened on such a scale that zoologists now refer to the modern era as a period of mass extinction.
Less visibly, ocean-going creatures are also disappearing. Sharks, marine mammals such as dolphins, and even Atlantic cod are at risk from overfishing.
But information is hard to come by. Oceans are huge and deep, and scientists can only guess at species numbers.
Turtles, however, come ashore to lay eggs, using the same nesting sites again and again. Researchers can count them as they go out, and as they come back. Leatherback numbers have declined by 90% in the past 22 years to about 900 in Indonesia, 45 in Mexico, 55 in Costa Rica and two in Malaysia. But, Dr Crowder said, extinction need not be inevitable. International cooperation had managed to reverse the decline of another sea turtle called Kemp’s ridleys. These were reduced to 300 nesting females in the 80s.
Then their nesting beaches in Mexico were protected and trawlers were fitted with turtle excluder devices, metal grids that allowed the turtles to slip away instead of being trapped.
Last year conservationists counted 6 200 Kemp’s ridleys.
Conservationists are looking at ways to prevent turtles being snared on the longlines set for swordfish. They are trying to work out where the turtles go, and when, so fishermen can avoid the most vulnerable grounds.
And they are hoping to put pressure on international fish markets by informing consumers.
Sea turtles get caught on swordfish lines 10 times more often than on hooks baited for tuna. ”So simply choosing to consume less swordfish could reduce market demand and reduce the impact on critically endangered leatherbacks,” Crowder said.
”Leatherbacks have been on earth 25 times longer than humans but we are the cause of the decline. We have been here about 4-million years, they have been here 100-million. Measured in evolutionary terms, leatherbacks are one of the most successful organisms in the sea, but unless things change they are not likely to be here much longer.
”They will disappear if things don’t change. The only disagreement is exactly how long it will take.” – Guardian Unlimited Â