Olive Ridley turtle lays eggs in Maharashtra after Odisha; experts say feat recorded for first time

An Olive Ridley turtle has opened up a plethora of research avenues for experts after becoming the first recorded instance of a member of the species laying eggs on the east and west coasts of the country.

The Olive Ridley turtle, tagged at Wheelers Island in Gahirmatha Marine Sanctuary on Odisha coast on March 18, 2021, has swam around 3,600 km through the Bay of Bengal to lay eggs in Guhagar beach in Maharashtra, prompting experts to emphasise the need for an elaborate scientific study of their migration behaviour.

The turtle, which had dug a hole at Guhagar beach with its flippers and laid 120 eggs, was spotted during a routine drill by turtle nest managers on January 27 this year when it was on its way back to the ocean, an official said. It was noticed that the turtle had been tagged with the initials ZSI and the number 03233, he said. Basudev Tripathy, a senior Zoological Survey of Indian scientist, said this was first recorded instance of a turtle that had previously nested on Odisha's coast migrating such a long distance to lay eggs.

"Generally, turtles tagged at Odisha nesting grounds to study their migration behaviour do not travel such long distances. Earlier, some tagged turtles were rescued from the northern coast of Sri Lanka by fishermen.

However, there has been no history of turtles tagged in the eastern state nesting in Sri Lanka," he pointed out. What makes the development significant is that for the first time it has been recorded that an Olive Ridley turtle has laid eggs on both the coasts of India, said Manas Manjerakar, the deputy director at Mangrove Foundation.

"It has also debunked the assumption that the turtles that lay eggs on the east coast do not go to the west coast. Earlier there was no such scientific evidence. This is why the development assumes significance," he told PTI. The Mangrove Foundation operates under the Mangrove Cell of the Maharashtra government and works for turtle conservation in the western state.

Tripathy said sea turtles typically migrate between foraging and nesting grounds, adding that male and female turtles migrate to breeding areas, usually returning to the beaches where they were born. "Given that a tagged turtle from the Odisha coast was found nesting for the first time on Maharashtra's coast, a more elaborate scientific study into the behaviour of these itinerant marine species is now in focus," Tripathy added.

He said earlier tagged Olive Ridley sea turtles have travelled around 1000 km in the sea to reach north Sri Lanka sea within a month from Gahirmatha Marine Sanctuary but they did not nest there. "This female turtle undertook an arduous journey of not less than 3,600 km to nest at the Maharashtra site. 'Arribada' (mass nesting) has only been recorded at Gahirmatha, Rushikulya and Devi river beaches in the state. This makes it crucial to undertake large-scale tagging of nesting turtles annually to further understand their behaviour," Tripathy said.

Explaining why the development is remarkable, Manjerakar said it is an established fact that Olive Ridley turtles nest across multiple beaches in a season or across years. "But this turtle nesting across the two ocean basins is the first of its kind. This is very important information which shows that the turtles that arrive to nest solitarily along the Maharashtra coast also join in to mass-nest along the Odisha coast," he said.

Of the 120 eggs laid by the turtle, 100 have hatched and baby turtles have been released in the sea, he said, adding it usually takes 50-60 days for the eggs to hatch. Manjerakar said the turtle had come to the Gahirmatha beach during the mass nesting phenomenon observed there. It was tagged by the Zoological Survey of India.

These metal tags were photographed and the details on these tags were sent to the research team from Wildlife Institute of India who are undertaking a study of the population of turtles along the Maharashtra coastline since 2023 in collaboration with the Maharashtra forest department.

"When the turtle nest managers (locals roped in for conservation) at the Guhagar beach came across the tag on two of its flippers, they shared it with the department. The Maharashtra government has come up with a similar initiative to tag turtles with the help of Wildlife Institute of India," he said. "When we exchanged notes, we came to know that the turtle had laid eggs in Odisha some four years ago," Manjerakar said.

The forest department hopes that after Maharashtra starts tagging turtles it will throw light on the movement of the marine amphibians. Turtle nesting takes place in primarily three coastal districts of Maharashtra, led by Ratnagiri, and followed by Sindhudurg and Raigad.

The Odisha Forest Department began turtle tagging in 1999, tagging around 1,000 turtles. Between 2021 and 2024, around 12,000 turtles have been tagged at the Gahirmatha and Rushikulya river mouth nesting sites. Mass nesting on Odisha's coast remains impressive. This year alone, around 10 lakh turtles arrived at the state's nesting beaches for arribada. "Tagging needs to be conducted on a much larger scale.

Currently, around 3,000 turtles are tagged annually. But we believe at least one lakh turtles need to be tagged to gain deeper insight into their reproductive biology, movements, growth rates, migratory routes, and foraging zones," Tripathy added.