Olive Ridley sea turtle- ECOLOGY

March 29, 2018

Did you know?

Olive Ridley babies grow on their own without their mothers around!

 

5 species of turtles are found in Indian waters: Leatherback, Loggerhead, Hawksbill, Green and Olive Ridley.

 

Why in news?

Despite Mumbai's polluted beaches, the Olive Ridley turtles seem to have found one beach clean enough to nest, with around 80 hatchlings making their way to the Arabian Sea in March 2018.

 

 

What are olive ridley sea turtles and where are they found?

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 spend their entire lives in the ocean, and migrate thousands of kilometers between feeding and mating grounds in the course of a year. 

Why the colour olive?

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. 

 

 

Status:

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.

 

Unique features:

  • 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.

  • 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. 

  • 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

 

Nesting grounds:

The coast of Orissa -Gahirmatha, Devi Nadi, (most preferred- Kendrapada & Rushikulya beach of Ganjam) in India is the largest mass nesting site for the Olive-ridley, followed by the coasts of Mexico and Costa Rica

Nesting occurs throughout tropical waters, except Gulf of Mexico.

Significance in marine ecosystem:

  • Sea turtles, especially the Leatherback, keep jellyfish under control, thereby helping to maintain healthy fish stocks in the oceans.

  • Green turtle feeds on sea grass beds and by cropping the grass provide a nursery for numerous species of fish, shellfish and crustaceans.

  • Hawkbill feeds on sponges in the reef ecosystem and opens up crevices for other marine life to live in.

  • Turtles are also transporters of nutrients and energy to coastal areas.

Concern:

  • Every year, thousands of turtles are accidently captured , injured or killed by mwchanised boats, trawl nets and gill nets operated and used by commercial fishermen. The process is called Bycatch.

    • It occurs when turtles begin migrating to their nesting grounds on beaches and in fishing areas that are their feeding grounds.

       

  • In 2003, nearly 6000 olive ridley turtles were found dead, of which more than 4,600 died outside the Gahirmatha Marine Sanctuary, near Astaranga

  • 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.

 

Threats:

  • 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.

  • Salination of beaches

  • 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.

  • The global net decline for the Olive Ridley is driven principally by population trends in just two arribada populations, Escobilla (México) and Ostional (Costa Rica), both in the Eastern Pacific.

Steps taken:

  • 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.

  • Odisha: Astaranga, near Puri, Odisha, a community-led initiative has provided the endangered Olive Ridley turtles a new nesting ground.

 

Suggestions:

  • Under current regulations, mechanised trawl boats are not allowed to operate within 8km of the shore in AP, 5.5km in TN, and 5km in Odisha.

NEED: Proper enforcement of the limits.

  • Net set for ray fish are banned under the law during the season. The ban needs to be enforced at all levels of fishing and monitored by the respective Fisheries departments, marine police and the Indian Coast Guard.

  • Use of TEDs: Turtle Excluder Devices.

These small but meaningful measures will help the sea turtles that are our marine heritage have another chance at survival.

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