Olive Ridley Turtles: Existential Paradox

Despite the relative abundance of the Olive Ridley today, their numbers have diminished by an astounding fifty percent during the last several decades. In the United States, they are labeled threatened or likely to come under danger of extinction in the foreseeable future. The International World Conservation Union (IUNC) has listed the species as endangered.
A primary threat to the Olive Ridley comes from human predation in the nesting habitat. 

The arribada with its large congregation of nesting females makes it possible for humans to collect huge quantities of eggs and kill or collect (to sell at market) hundreds or even thousands of turtles in one night.  This practice of mass harvesting and killing over the past sixty years has caused local populations to plummet in many areas of the globe. Another form of human intrusion that threatens sea turtles is the permanent destruction of the nesting habitat through coastal degradation and development.

Thousands of Olive Ridley are killed annually at sea, becoming collateral damage to the practices of shrimp trawling and commercial fishing. It is estimated that 60, 000 sea turtles—mostly Olive Ridley —die every year as incidental bycatch in shrimp trawls along the coast of Central America (Arauz 1996). These losses could be avoided if regulations requiring turtle excluder devices (TEDs) were enforced. Other fishing practices such as the use of longlines and gill nets also contribute to the decimation of the Olive Ridley and other sea turtles in the open ocean.

The Olive ridley turtles are the smallest and most abundant of all sea turtles found in the world, inhabiting warm waters of the Pacific, Atlantic and Indian oceans. These turtles, along with their cousin the Kemps ridley turtle, are best known for their unique mass nesting called Arribada, where thousands of females come together on the same beach to lay eggs. Though found in abundance, their numbers have been declining over the past few years, and the species is recognized as Vulnerable by the IUCN Red list.

Growing to about 2 feet in length, and 50 kg in weight, the Olive ridley gets its name from its olive colored carapace, which is heart-shaped and rounded. Males and females grow to the same size; however, females have a slightly more rounded carapace as compared to the male. They are carnivores, and feed mainly on jellyfish, shrimp, snails, crabs, molluscs and a variety of fish and their eggs. These turtles spend their entire lives in the ocean, and migrate thousands of kilometers between feeding and mating grounds in the course of a year. 

Interestingly, females return to the very same beach from where they first hatched, to lay their eggs. During this phenomenal nesting, up to 600,000 and more females emerge from the waters, over a period of five to seven days, to lay eggs. They lay their eggs in conical nests about one and a half feet deep which they laboriously dig with their hind flippers. The coast of Orissa in India is the largest mass nesting site for the Olive-ridley, followed by the coasts of Mexico and Costa Rica. 

After about 45-65 days, the eggs begin to hatch, and these beaches are swamped with crawling Olive-ridley turtle babies, making their first trek towards the vast ocean. During this trek they are exposed to predators like jackals, birds, hyenas, fiddler crabs, and feral dogs lurking around, waiting to feed on them. WWF-India, along with the fishermen community, has been involved in protecting the Olive ridley rookery at the mass nesting site at Rushikulaya, in Orissa, by fencing off the nesting area and patrolling it till hatching and ensuring a safe passage for the hatchlings to the sea. It is estimated that approximately 1 hatchling survives to reach adulthood for every 1000 hatchlings that enter the sea waters. This may also be the reason why arribadas happen and a single female can lay 80 to 120 eggs and sometimes even twice in a season; to increase the hatchlings survival rate.

Olive-ridleys face serious threats across their migratory route, habitat and nesting beaches, due to human activities such as turtle unfriendly fishing practices, development and exploitation of nesting beaches for ports, and tourist centres. Though international trade in these turtles and their products is banned under CITES Appendix I, they are still extensively poached for their meat, shell and leather, and their eggs, though illegal to harvest, have a significantly large market around the coastal regions. However, the most severe threat they face is the accidental killing of adult turtles through entanglement in trawl nets and gill nets due to uncontrolled fishing during their mating season around nesting beaches.

To reduce accidental killing in India, the Orissa government has made it mandatory for trawls to use Turtle Excluder Devices (TEDs), a net specially designed with an exit cover which allows the turtles to escape while retaining the catch. However, this has been strongly opposed by the fishing communities as they believe TEDs result in loss of considerable amount of the catch along with the turtle. WWF-India, along with its partners, disproved this theory by conducting a study to measure the loss of catch through TEDs, revealing the loss to be a very small percentage of the total catch. This result, along with regular meetings with the fishing communities, is slowly helping to change their mindset and encourage use of TEDs, thereby aiding the conservation of Olive ridley turtles.