Over the past two weeks, numerous dead olive ridley turtles have washed ashore in Tamil Nadu, particularly in Chennai. Experts have estimated that so far, between 300 and 350 turtles have been found dead. Olive ridley turtles arrive near the Tamil Nadu coast around September-October to breed. Their nesting season begins in late November and ends in March. Although deaths during nesting season are not unusual, the large number of turtle carcasses found this early in the nesting period has sparked concerns among conservationists and citizens. Where have carcasses been found? Speaking to The Indian Express, Supraja Dharini, founder of the Tree Foundation, a non-profit which works on sea turtle conservation, said that dead olive ridley turtles have been found across Chennai and neighbouring Kancheepuram district. “Dead turtles have been reported in Neelankarai, Besant Nagar, Kovalam right up to areas of Kancheepuram district,” she said. Officials of the state Forest Department said that they were still collating exact data on the mortalities. Deaths have also been reported from Pulicat in Thiruvalluvar district, north of Chennai, according to officials. Volunteers of a few other conservation organisations said they have been getting calls from citizens in and around Chennai, reporting sightings of turtle carcasses from different beaches. What is the reason behind the deaths? Finding carcasses of olive ridley turtles is not uncommon during their mating season. The turtles mate near shore areas and females arrive in small batches for nesting on Tamil Nadu’s beaches. As a result, they often get trapped in long fishing nets of commercial trawlers as bycatch — the unintentional capture of non-target marine life — and die, according to experts. K Sivakumar, professor at the Department of Ecology and Environmental Sciences, Pondicherry University, said, “Olive ridley turtles have to swim up to the sea surface to breathe. If they get tangled in nets, they asphyxiate and die.” This year, however, the increase in the number of deaths could be because of a large availability of fish close to the turtle gathering areas, according to Sivakumar. Due to more fish near the turtle gathering areas, more trawlers would have been there, leading to the deaths of turtles, he said. Besides, since turtles are omnivorous, they might feed on fish in areas where the fishing vessels were operating, Sivakumar said. Post-mortem of a carcass has revealed lesions on the lungs, indicating suffocation of the turtles, Manish Meena, wildlife warden of Chennai said. Carcasses also had bulging eyes and swollen necks which indicated death due to drowning, Dharini said. Sivakumar suggested that there should be a comparative analysis of the fish catch landings from Chennai’s harbours of this year with the corresponding period of previous years to ascertain if there has been a spike in fish catch. He also said that authorities ought to strictly enforce the use of turtle-excluding devices, which are fitted into nets, allowing incidental bycatch to escape through a flap in the nets. How does the nesting season unfold? Olive ridley turtles lay eggs across several coastal states on India’s east coast and west coast. However, mass nesting takes place in Odisha, followed by Andhra Pradesh and Tamil Nadu. Odisha’s Gahirmatha and Rushikulya beaches witness the arrival of lakhs of female olive ridley turtles every year. They make nests in the sand using their flippers and lay between 100 and 110 eggs each. After laying the eggs, they cover the nests with sand to prevent predation and return to the sea. After 45-60 days, thousands of hatchlings make their way to the ocean. At nesting sites where human disturbance and predation are likely, Forest Departments create hatcheries. The eggs are retrieved from the nests with care and are placed in hatcheries. After the eggs hatch, the juveniles are placed in baskets and released near the sea.
