Research says

An olive raile turtle hatched. File | Image source: AP

A study based on large-scale nesting that monitors marine life for more than 15 years, with rising temperatures affecting the sex ratio of endangered olive Ridley turtles, with a higher number of female turtles found at the estuary of Rushikulya in Ganjam district of Odisha.

The study titled “Monitoring Turtles in India 2008-2024” said: “For the past 15 years, we have been monitoring the nest temperature and hatching gender ratios of Rushikulya Rookery. Determining hatched sex through gonadal histology helps monitor the primary gender ratio of isolated and Arribada nests.”

Ridley Turtles are known for their unique synchronous nesting strategy, known as Arribada (“arrival” in Spanish).

During these massive nesting events, thousands of female turtles nest on the beach in just a few days. Large olive Ridley Arribadas appear only on Central America and the east coast of India. The East Coast population of Indian Olive Ridge is particularly interesting because it is considered a genetically unique and is an ancestral source of the global Olive Ridge, the study said. Odisha is home to two largest mass nesting sites – Gahirmatha and Rushikulya.

“This data is useful for building a critical temperature for the population. Rushikulya’s gender ratio tends toward women, but is not biased in some global turtle populations,” it said.

The study shows that estimating the sex ratio of juveniles produced in this show is useful for understanding the future effects of climate warming. It says that as global temperatures rise, turtle populations may become increasingly feminine.

The study found: “The average gender ratio of the Arribadas in Rushikulya was found to be about 71%. Although the proportion of female bias in some years is extremely high due to high nest temperatures, the sex ratio of male bias has been generated over the years.”

The study observed: “Nevertheless, the types of data we can collect on rookies. However, with the help of additional temperature data, we aim to use an embryo growth model to examine the long-term trend of the incubation ratio of Rushibadas from Rushibadas.”

Since 2008, the Daksin Foundation and the Ecological Science Center, the Indian Academy of Sciences in Bangalore has partnered with the State Forest Ministry to monitor Olive Ridley Turtles in Odisha.

“Long-term monitoring and data generated from it can be used to understand trends in populations and predict the future impacts of climate change. They can also guide policy and determine consistency actions. In particular, they can help design strategies that are inclusive of local communities towards long term benefits for turtles, ecosystems and people,” said Kartik Shanker, one of India’s foremost researchers on Olive Ridley turtles.

Since 2008, large-scale nesting events held in Rushikulya almost every year have occurred within the range of one to two million Ulas. This suggests that the Ridley population in the region is either stable or increased. However, the average incubation temperature of the nest usually exceeds the critical temperature, resulting in a female biased hatching gender ratio.