In India, leatherback turtles nest mainly in the Andaman and Nicobar islands. But where they go from there is not known.
Leatherback turtles are the largest of living sea turtles, growing up to two metres and weighing as much as 900 kg. They are known for their remarkable migrations, travelling several thousands of kilometres from breeding to feeding grounds. These animals can dive as deep as 1200 metres, and range into sub-arctic waters in search of their favourite food, jellyfish.
In India, leatherback turtles nest mainly in the Andaman and Nicobar islands, but nothing is known about where they go once they have finished nesting. The Indian Institute of Science (IISc), Bangalore has been conducting a long-term tagging and monitoring programme on Little Andaman Island in collaboration with the Andaman and Nicobar Environment Team (ANET) and the Andaman and Nicobar Forest Department since 2008.
In January 2011, we from the Centre for Ecological Sciences, IISc, and the ANET field team tagged three leatherback turtles with satellite transmitters to track the post-nesting movements of these animals. This study, funded by the Space Technology Cell at IISc, is the first telemetry study of leatherback turtles in South Asia. Initial results show the turtles swimming southwards in the Indian Ocean. Turtle 103335 has already covered 2500 km, and is currently south of Sumatra.
Adult leatherbacks are excellent swimmers, capable of swimming continuously at an average 45-65 km per day. Clumsy and laborious looking on land, these animals are designed for the water, with streamlined bodies and powerful front flippers. Remarkably, they can also regulate their body temperatures to a certain extent, unlike most reptiles.
Leatherback sea turtles nest at intervals of two to three years. They nest between four to seven times per season, with an average of nine days between each nesting. Each nest contains an average of 80-100 eggs. Eggs incubate for about 60-65 days before the hatchlings emerge.
Leatherback nesting beaches in Great and Little Nicobar Island were washed away during the December 2004 tsunami. This nesting population, particularly the Nicobar population, is considered to be the largest in the southern Asian region. Recent surveys by Naveen Namboothri and Saw Agu indicate that the beaches are forming again, and that there is a fair amount of nesting at these beaches.
There is great concern over the drastic declines in the nesting populations of this species throughout the world, especially in the Pacific. In the Andamans, leatherback turtles are subject to a variety of threats on land, such as depredation of eggs by feral dogs and pigs, and at sea, mainly fisheries. Ongoing studies using genetics and telemetry will provide insights into the biology of these animals which will help in their conservation.
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Keywords: Leatherback turtles