In News:

The Rushikulya river mouth in Odisha is witnessing the anticipated mass nesting of Olive Ridley turtles — a critical event for the survival of this vulnerable marine species. This phenomenon, known as arribada, highlights the ecological significance of India’s coastal biodiversity and the urgent need for marine conservation.

About Olive Ridley Turtles (Lepidochelys olivacea)

• Taxonomy:
  • Scientific Name: Lepidochelys olivacea
  • Class: Reptilia
  • Family: Cheloniidae
• Physical Features: These turtles are the smallest and most abundant of all sea turtle species. They are recognized by their olive or grayish-green heart-shaped carapace. Males and females are similar in size, though females have slightly rounder shells.
• Habitat and Distribution: Olive Ridleys are found in warm, tropical waters of the Pacific, Atlantic, and Indian Oceans, inhabiting both open ocean (pelagic) and coastal waters.

Mass Nesting: The Arribada Phenomenon

• Arribada (Spanish for "arrival") refers to the synchronized mass nesting behavior where thousands of females gather on a single beach to lay eggs.
• Nesting occurs annually between December and March, after long migrations of up to 9,000 km. Each female may lay 90–120 eggs, 1 to 3 times per season.
• Temperature-dependent sex determination influences hatchling sex ratios.
• After nesting, females return to the sea, leaving eggs buried in sand.

Major Nesting Sites in India

• Odisha Coast is the most significant nesting ground in India and globally:
  • Gahirmatha Marine Sanctuary: World’s largest mass nesting site.
  • Rushikulya River Mouth: Second-largest nesting beach in India.
  • Devi River Mouth: Another key nesting site in Odisha.
• Andaman and Nicobar Islands have recently emerged as a new mass nesting area, with over 5,000 nests reported in one season.

Ecological Role and Behavior

• Diet: Omnivorous — they feed on jellyfish, crabs, snails, prawns, molluscs, algae, and small fish.
• Behavior: These turtles undertake long migrations annually between feeding and breeding grounds, spending most of their lives at sea.

Protection Status

• IUCN Red List: Vulnerable
• CITES: Appendix I
• Wildlife (Protection) Act, 1972 (India): Schedule I (highest protection)

Threats to Survival

• Bycatch in Fishing Gear: Accidental entanglement in trawls, gillnets, and longlines.
• Habitat Loss: Coastal development for ports, tourism, and industry disrupts nesting beaches.
• Poaching: Turtles and their eggs are harvested for meat, shell, and leather.
• Pollution: Plastic ingestion and marine debris pose severe health risks.
• Climate Change: Rising sea levels and increased sand temperatures impact nesting and hatchling sex ratios.

Conservation Initiatives

• Operation Olivia: Initiated by the Indian Coast Guard in the 1980s to protect turtles during nesting and prevent illegal fishing.
• Turtle Excluder Devices (TEDs): Mandated by the Odisha government in trawl nets; allow turtles to escape while retaining fish catch.
• Tagging Programs: Use of non-corrosive metal tags to study migration patterns and inform conservation strategies.