Why dead Olive Ridley turtles are washing ashore in Tamil Nadu?

Why in the NEWS?

• About 300 to 350 dead Olive Ridley turtles have washed up on the beaches of Tamil Nadu, especially Chennai, in the last two weeks, and experts estimate that the number could rise.

Key Points:

• Olive Ridley turtles come to Tamil Nadu coasts every year in September-October to breed. Their nesting season begins in November and ends in March.
• Though the death of turtles during nesting is not uncommon, this time the discovery of a large number of dead turtles in the initial stages of nesting has raised concerns.
• The dead turtles have been found in various places in Chennai and Kanchipuram district. The major locations include Neelankarai, Besant Nagar, Kovalam, and areas in Kanchipuram district.

What will you read next in this topic?

1. Causes of Olive Ridley Turtle Deaths:
2. Olive Ridley Turtle Nesting Season:
3. Olive Ridley Turtles: A Detailed Introduction
4. Tagging and Conservation of Olive Ridley Turtles
5. Zoological Survey of India (ZSI)

Causes of Olive Ridley Turtle Deaths:

• Deaths common during breeding season: 
  • Olive Ridley turtles come to coastal areas during breeding season, and their deaths during this time are not an uncommon occurrence.
• Deaths due to trawling: 
  • Turtles come to beaches for breeding, and during this time they get caught in the nets of commercial fishing trawlers, which also catch non-target marine life. This often leads to turtle deaths.
• Deaths due to suffocation: 
  • According to K Siva Kumar, professor of Pondicherry University, turtles have to swim to the surface of the sea to breathe, but they get suffocated to death when they get caught in the nets.
• Fish availability and number of trawlers: 
  • Due to the large availability of fish near the turtle aggregation areas, more fishing trawlers were active there, which has led to increased turtle deaths.
• Feeding habits of turtles: 
  • Turtles are omnivorous and eat fish, so they may also visit areas where fishing vessels are active.
• Post-mortem report: 
  • Post-mortem of turtle carcasses revealed lesions on their lungs, indicating suffocation. 
  • The carcasses had bulging eyes and swollen necks, indicating death by drowning.
• Comparative study of fishing numbers: 
  • A comparative study of fishing numbers from Chennai ports this year with previous years should be done to find out the increase in catches.
• Need for turtle-deterrent devices: 
  • Authorities should strictly enforce the use of turtle-deterrent devices to avoid accidental by catch and turtles to escape from the nets.

Olive Ridley Turtle Nesting Season:

• Olive Ridley turtles nest in many coastal states of the east and west coast of India, but Odisha is the largest breeding site, followed by Andhra Pradesh and Tamil Nadu.
• Lakhs of female turtles come to nest every year on the Gahirmatha and Rushikulya beaches of Odisha.
• The female turtles build nests in the sand using their fins and lay 100 to 110 eggs in each nest.
• After laying eggs, the female turtles cover their nests with sand to avoid predators and then go back to the sea.
• After 45-60 days, thousands of babies head towards the sea.
• In places where there is a possibility of human disturbance and hunting, the forest department builds hatcheries.
• The eggs are carefully removed from the nests and placed in hatcheries. After hatching in the hatcheries, the babies are placed in baskets and released near the sea.

Olive Ridley Turtles: A Detailed Introduction

• Olive Ridley turtles are the most commonly found sea turtles. The shell of these turtles is olive in colour, which is why they are called "Olive Ridley".
• A unique feature of these turtles is that they collectively make nests, which is called Arribada.
• Olive Ridley turtles are mainly found in warm waters of the sea.
• They live especially in coastal areas located along the Pacific, Atlantic and Indian Oceans.
• Their main breeding site is Gahirmatha Marine Sanctuary (Odisha), which is considered to be the world's largest sea turtle breeding site.
• Every year millions of female Olive Ridley turtles come to this area of ​​Odisha to lay eggs.

Conservation status:

• The Olive Ridley turtle species needs conservation at the global level.
• Concerns have been expressed by various conservation organizations and institutions regarding the status of this turtle.

IUCN Red List:

• Olive Ridley turtles are classified as Vulnerable, that is, this species is endangered and needs protection.

CITES (Convention on International Trade in Endangered Species):

• This species is listed in CITES Appendix-I, which means that the trade of this species is completely banned so that it can be protected from hunting and trade.

Wildlife Protection Act, 1972:

• In India, this turtle is included in Schedule-1, which gives it full protection by Indian law.

Tagging and Conservation of Olive Ridley Turtles

Tagging Process:

• Researchers from the Zoological Survey of India (ZSI) have tagged Olive Ridley turtles in various coastal areas of Odisha, such as Gahirmatha, Devi River Estuary and Rushikulya.
• In 2021, about 1,556 turtles were tagged in Odisha, after nearly 25 years.

Features of the tags:

• The metal tags applied on these turtles are non-corrosive, i.e. they do not cause any harm to the turtles' bodies and can be easily removed.
• The tags contain details such as the organization's name, country-code, and email address.
• When researchers from other countries find tagged turtles, they send the information about the turtles' location (longitude and latitude) to researchers in India, thereby creating a network at the global level.

Purpose of tagging:

• Migration routes and nesting sites of turtles are revealed through tagging.
• It helps in identifying the places visited by turtles following their travel and congregation, thereby helping towards conservation.

Conservation Initiatives

Operation Olivia:

• Operation Olivia is conducted annually by the Indian Coast Guard.
• Its main objective is to protect Olive Ridley turtles, especially when these turtles congregate for breeding and nesting on the Odisha coast.
• This operation helps in preventing illegal trapping activities.

Turtle Excluder Devices (TED):

• The Odisha government has made the use of TED mandatory in fishing trawlers.
• TED provides a special exit cover, which helps turtles trapped in the net to exit. This is an important step to prevent accidental deaths of turtles in the nets.

Zoological Survey of India (ZSI)

• ZSI was established in 1916 and functions under the Ministry of Environment and Forests, India.
• The main objective of ZSI is to survey and study natural resources and fauna, to understand their status and conservation measures.
• ZSI is headquartered in Kolkata, and has 16 regional stations located at different geographical locations in India, facilitating conservation work across the country.