Olive Ridley turtles are seen at the Rushikulya river mouth beach in Ganjam district of south Odisha as they nest their eggs on their mass nesting season on the Bay of Bengal Sea’s Odisha coast.
| Photo Credit: Biswaranjan Rout

A 16-year-long assessment of trends in turtle populations in India says the numbers of the Olive Ridley species suggest a “steady or growing” population. However, rising sand temperatures due to climate change are causing a large proportion of these turtles to be females “raising questions” on the long-term viability of the population.

The report, spanning studies from 2008 to 2024, has been prepared by the Dakshin Foundation and is a long-term monitoring project carried out in partnership with the Indian Institute of Science (IISc), Bengaluru, and several State forest departments. It provides important information about population trends, threats, and conservation along India’s mainland and island coasts. Along with the Olive Ridley, the most populous of marine turtles, the study encompasses other species of sea turtles found in the Indian territory such as the leatherback turtles of Andaman and Nicobar islands and the green turtles of the Lakshadweep islands.

Sea turtles are long-lived, late-maturing, and highly migratory species. Any changes in their populations occur over years or decades, making long-term monitoring essential for understanding population trends and environmental impacts.

A striking natural phenomenon that evokes considerable public interest is the ‘arribada’ or mass nesting of the Olive Ridley turtle, when tens or hundreds of thousands of female turtles come ashore to nest simultaneously. Gahirmatha and Rushikulya in Odisha are two of the largest ‘rookeries’ or nesting grounds worldwide, with other similar sized ones found only in Mexico and Costa Rica. This month, Rushikulya witnessed one of the largest arribadas in recent years, with 400,000 to 500,000 turtles nesting in a span of just a few days. Some sections of the beach were so tightly occupied by the turtles that there was barely any room to walk.

“The overall trend from nearly two decades of monitoring is that the Ridley population is stable or increasing. The fact that arribadas don’t occur in some years is puzzling as our offshore monitoring indicates that there are large numbers of turtles in the water. However, it may not be a cause for immediate alarm. Nevertheless, we must remain wary of threats to both coastal and oceanic habitats,” Professor Karthik Shankar, who led the study and is associated with the Dakshin Foundation and the IISc, said in a statement.

Globetrotting turtles

Since the 2004 Indian Ocean tsunami, leatherback turtle nesting has steadily increased in Little Andaman Island. Telemetry studies, which analyse their migratory patterns, show that from 2011-2014, these turtles travelled as far west as Madagascar and Mozambique, while others headed as far east as Western Australia. In the Lakshadweep, an expanding green turtle population has brought about unexpected ecological changes, especially in the seagrass meadows, which are currently being overgrazed.

Turtle populations continued to face threats from causes such as coastal development, pollution and climate change. In India, sea turtle foraging and breeding sites overlap with important fishing grounds, affecting coastal livelihoods. “A key lesson from this nearly two-decade study is that local communities are primary stakeholders in monitoring and protecting sea turtles. Collaborations among fishers, researchers, and policymakers can lead to more sustainable conservation, benefiting both marine biodiversity and human well-being,” an accompanying press statement noted.