KENDRAPARA: A new study has found that Olive Ridley sea turtles nesting in Odisha are genetically distinct from global populations, and significantly differ from those in Sri Lanka.
The study, jointly by Wildlife Institute of India (WII), Dehradun and the Centre for Cellular and Molecular Biology (CCMB), Hyderabad, was published in a report ‘Monitoring Sea Turtles in India 2008- 2024’ by the Indian Institute of Science (IISc) and Dakhin Foundation of Bengaluru.
Scientists of WII and CCMB examined the molecular genetics of sea turtles along the mainland coast and islands of India. It suggested the Indian Olive Ridley sea turtles and Kemp’s Ridley sea turtles could be remnants of a global population which was otherwise extirpated following climatic changes before and after the closure of the Isthmus of Panama. The Indian Ocean region, thus, may have served as a source for Ridley re-colonisation following the extirpation of populations in other ocean basins.
Long-term monitoring of nesting and foraging populations is vital to detect biologically significant trends and patterns for species like sea turtles. The Dakhin Foundation, in collaboration with IISc and Forest department, initiated research and monitoring in the late 2000s for Olive Ridley sea turtles in Odisha and leatherback turtles in the Andaman and Nicobar Islands.
“We conduct long-term monitoring and tagging of leatherback turtles in Little Andaman Island accompanied by periodic surveys of the entire island group, including the Nicobar Islands. In the Lakshadweep Islands, Dakhin Foundation has been monitoring green turtles and their foraging habitat in the lagoons of several islands,” said Muralidharan Manoharakrishnan, noted turtle biologist and a senior wildlife researcher of WWF- India.
Following the surveys by noted turtle researcher Satish Bhasker, the Andaman Nicobar Environment Team (ANET) initiated monitoring of the leatherback sea turtles nesting beach at Galathea, Great Nicobar in 2001 which involved tagging and monitoring leatherback turtles. However, these beaches were destroyed by the 2004 tsunami and many other important nesting beaches were also severely affected. These beaches have since reformed and nesting numbers have returned to pre- tsunami levels.
Research of Green and Hawksbill sea turtles has been minimal up to this point, primarily due to their low abundance and limited distribution range in India. Past studies have primarily focused on nesting surveys but in the last decade, the Nature Conservation Foundation (NCF) has been studying the effects of increased herbivory by green turtles on sea grass meadows in the lagoons of the Lakshadweep Islands and as well as consequent conflict with fishers, added Manoharakrishnan.
The studies revealed that while some of the turtles remain in the offshore sea waters of Odisha, many others migrate to Sri Lanka and the Gulf of Mannar, said BC Chaudhury, noted turtle biologist and the former wildlife scientist of WII.