Olive Ridley Turtles
Context:
Over the past two weeks, around 300 to 350 olive ridley turtle carcasses have washed ashore along Tamil Nadu’s coastline, particularly in Chennai, raising alarm among conservationists.
Early Spike in Mortalities
- Olive ridley turtles typically arrive near the Tamil Nadu coast between September and October to breed, with their nesting season spanning late November to March.
- While some deaths during this period are expected, the unusually high number of carcasses this early in the season has raised red flags.
The olive ridley turtle (Lepidochelys olivacea) is the smallest and most abundant species of sea turtle, known for its distinctive heart-shaped, olive green carapace. Adults typically measure between 2 to 2.5 feet (62-70 cm) in length and weigh between 77 to 100 pounds (35-45 kg). These turtles inhabit tropical and subtropical waters across the Pacific, Atlantic, and Indian Oceans. A notable feature of the olive ridley is its unique nesting behaviour known as arribada, where thousands of females come ashore simultaneously to lay eggs, with each clutch averaging over 110 eggs that incubate for approximately 52 to 58 days. Despite their abundance, olive ridley turtles are classified as Vulnerable by the International Union for Conservation of Nature (IUCN) due to threats such as direct harvesting, incidental capture in fisheries, and habitat loss. Their diet consists mainly of crustaceans, molluscs, jellyfish, and fish, and they are capable of diving to depths of around 500 feet (150 m) in search of food.
Causes of Death
- The primary cause of olive ridley turtle deaths during mating and nesting season is accidental entanglement in fishing nets.
- These turtles, which mate in nearshore waters, often get caught in the long fishing nets of commercial trawlers. Unable to surface for air, they asphyxiate and die.
- Post-mortem examinations of carcasses revealed lesions on the lungs, indicating suffocation.
- Other signs include bulging eyes and swollen necks, consistent with drowning.
Preventive Measures
- Experts suggested that a comparative analysis of fish catch data from Chennai’s harbours this year versus previous years could help determine whether a spike in fish landings has contributed to the increased deaths.
- There is a need for stricter enforcement of turtle-excluding devices (TEDs) in fishing nets.
- These devices allow turtles and other bycatch to escape through a flap in the net.
Olive Ridley Nesting Process
- Olive ridley turtles nest along several coastal states in India, with mass nesting primarily occurring in Odisha, Andhra Pradesh, and Tamil Nadu.
- In Odisha, beaches like Gahirmatha and Rushikulya witness the arrival of lakhs of female turtles annually.
- Each turtle lays between 100 and 110 eggs in nests made using their flippers.
- After covering the nests with sand to protect them from predators, they return to the sea.
- Hatchlings emerge after 45-60 days and make their way to the ocean.
- In areas with high human disturbance or predation, Forest Departments set up hatcheries where eggs are carefully relocated, incubated, and later released as hatchlings near the sea.
The recent deaths underscore the urgent need for conservation efforts and stricter regulations to protect olive ridley turtles.
