Tsunami Pushes Leatherback Turtles Toward Brink
NEW DELHI — They survived the dinosaurs, but leatherback turtles may have moved one step closer to extinction when last December’s tsunami washed away some of their most important nesting beaches in India’s Nicobar islands.
The remote Nicobars, more than 1,300 km (800 miles) east of the Indian mainland, are one of the world’s four most important nesting sites for the critically endangered leatherback, the largest living marine reptile.
“We have lost three major beaches which are globally significant,” said Harry Andrews of the Madras Crocodile Bank, who has been surveyeing the population for years.
“I am not sure whether those beaches will form again because water has gone far inland. If that is the case, leatherback turtles are going to have a major problem.”
The leatherback is fast losing its battle with man, the global population of adult females falling from 115,000 in 1980 to fewer than 25,000 today. It is already close to extinction in the Pacific, and could disappear entirely in a matter of decades.
Fishing is a major culprit, with nets snagging the turtles and propellers slicing through their flesh. Development and disturbance of their nesting sites is even more of a threat.
That is why the relatively undeveloped Nicobars are so important. A recent survey found at least 3,000 nesting there.
Major Population May Go
But the islands, close Indonesia’s Sumatra, sank up to 2 meters (six feet) into the sea after the tectonic shifts which caused the Dec. 26 earthquake.
The world-renowned Galathea beach on Great Nicobar, where tourists would come to watch the leatherbacks haul themselves up onto the sand every year to nest, has been largely washed away.
Three other turtles, including the hawksbill and the olive ridley, also nest on the islands.
Andrews said those could find new beaches to nest, to replace the ones lost. The monsoon may also create new beaches this year.
But the larger leatherback, which can grow to more than 2 meters (six feet) long and weigh up to 500 kg (1,100 lb), could find it harder finding new nesting sites.
“They wont be able to find other beaches because the beaches are too small or too close to reefs,” said Andrews. “They need deep water and nest at the mouth of rivers or creeks. For some reason they also don’t swim over reefs for nesting.”
“We may lose one of three largest populations in the world.”
Leatherbacks have been around for at least 65 million years. They can dive up to 1,000 meters (3,300 feet) in search of their favorite food, jellyfish, migrate hundreds of kilometers (miles) every year and even can in arctic waters.
Even before the tsunami, Andrews and other experts were increasingly worried about the future of marine turtles in the Nicobars and their sister islands, the Andamans to the north.
Fishing kills up to 3,000 of them every year in the archipelago. One survey found 40 percent of leatherbacks nesting on Great Nicobar had propeller gashes, some bleeding profusely.
Sand mining for buildings has also destroyed 16 nesting beaches in the Andamans alone since 1981. Feral dogs, domestic pigs and tourism are also deadly threats.
While the Nicobars sank, the Andaman group was raised by the earthquake, exposing reef flats around many islands. That has made several important nesting sites inaccessible.
On the Indian mainland coast of Tamil Nadu, the tsunami was better news for the olive ridley, whose numbers had been steadily increasing recently thanks to strenuous conservation efforts.
Every year, turtles were killed by trawlers or snagged in nets, but the decline in fishing after the tsunami allowed more to nest safely in Tamil Nadu than for many years.