Olive Ridley Turtles

Context:

Researchers of the Zoological Survey of India (ZSI) are carrying out tagging of Olive Ridley turtles at three mass nesting sites – Gahirmatha, Devi River mouth and Rushikulya.

About Olive Ridley Turtles:

• The olive ridley sea turtle also known commonly as the Pacific ridley sea turtle,
• It is a species of turtle in the family Cheloniidae.
• The species is the second-smallestand most abundant of all sea turtles found in the world. 
• L. olivacea is found in warm and tropical waters, primarily in the Pacific and Indian Oceans, but also in the warm waters of the Atlantic Ocean.
• This turtle and the related Kemp’s ridley turtle are best known for their unique mass nesting sites called arribadas, where thousands of females come together on the same beach to lay eggs
• Protection Status:
  
  
  • Wildlife Protection Act, 1972: Scheduled 1
  • IUCN Red List: Vulnerable
  • CITES: Appendix I

Tagging and its Significance:

• The metal tags affixed to turtles are non-corrosive, which can be removed later and they do not harm their body.
• The tags are uniquely numbered containing details such as the name of the organisation, country-code and email address.
• If researchers in other countries come across the tagged turtles, they will email their location in longitude and latitude to researchers in India. There is an established network working on turtles.
• It would help them identify the migration path and places visited by the marine reptiles after congregation and nesting.

Olive Ridley Turtle Mass Nesting in India

In India, Gahirmatha beach off the Bay of Bengal coast in Kendrapara district is acclaimed as the world’s largest nesting ground of these turtles.

According to the Indian Coast Guard, the following points are to be noted about the smallest sea turtles – Olive Ridley:

1. First Mass Nesting of these turtles was discovered in 1974. It was Gahirmatha rookery close to the mouth of Brahmani-Baitarani (Dhamra) River.
2. A second mass nesting was discovered in 1981 at the Devi River mouth.
3. The third mass nesting area was discovered at the Rushikulya river mouth in 1994.
4. The turtles come together at the Odisha Coast in November and December annually and stay up to April and March for nesting.
5. 100 to 140 eggs are laid by the adult female turtle at a time.

Other relevant facts about these turtles are:

1. The Odisha Coast has the right kind of nesting beaches around river mouths. The deltaic areas with sand pits in this coast is a suitable nesting site for turtles as they like it.
2. Olive Ridley seeks a specific latitude for nesting. A beach located at a latitude of around 25 degrees is what these turtles seek.
3. The olive ridley’s sense of magnetic field is responsible for their set behaviour. Environmental cues like sea currents, the sun’s position, surface winds, temperature, seasons and moon are taken into account by the turtles.
4. After hatching, adult turtles usually leave their eggs and swim away, and these hatchlings use these environmental cues only to get to foraging grounds.

Olive Ridley Turtles Conservation in India

Olive Ridleys in India are found from the Gujarat coast to the Andamans and Lakshadweep to Odisha and Bengal. These turtles make their journey from Australia to India of around 9000 km.

Read about India’s Operation Olivia concerning Olive Ridley Turtles in the linked article.

Threats to Olive Ridley Turtles :

The state government of Odisha has listed down the following threats to the Olive Ridley Turtles:

• Loss or modification of the nesting beaches due to Casuarina plantation
• Fishing by gill nets; and development of fishing bases at the potential nesting sites and breeding areas
• Strong illumination around nesting beaches greatly disorients the adult turtles as well as the hatchlings
• Large scale vessel movement in congregation zones severely disturb mating and breeding
• Nests and eggs are destroyed by predators like dogs, jackals, hyenas, etc., and by beach erosion.

These sea turtles have been given legal protection under Schedule 1 of the Wildlife Protection Act 1972.

The Olive Ridley Turtles are also protected by CITES under Appendix 1.

They are also listed in the Convention on Migratory Species (CMS), also called Bonn Convention.

Odisha Government Initiatives

In Odisha, the population that congregates yearly represents about 50% of the total world population of Olive Ridleys and about 90% of the Indian population of sea turtles.

To protect the nesting and breeding habitat of Olive Ridley Turtles, the waters around Bhitarkanika were declared as Gahirmatha (Marine) Wildlife Sanctuary in September 1997.

Odisha Marine Fisheries Regulation Act (OMFRA) 1982 and Odisha Marine Fisheries Regulation Rules, 1983 have declared the coastal waters off Devi and Rushikulya rookery as a no-fishing zone during the sea turtle breeding season. Indian Coast Guard has been authorized to enforce the provisions of these acts.

Turtle Excluder Devices (TEDs)

These are 2-D net inserts that have large escape openings for turtles. These are compulsory to be used by the trawlers while shrimp fishing.

Zoological Survey of India (ZSI)

• It is a subordinate organization of the Ministry of Environment, Forest and Climate Change, established in 1916.
• It is a national centre for faunistic survey and exploration of the resources leading to the advancement of knowledge on the exceptionally rich faunal diversity of the country.
• It has its headquarters at Kolkata and 16 regional stations located in different geographic locations of the country.

Source: The Hindu

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