Olive ridley turtle (Pacific ridley)

Common name: olive ridley turtle (Pacific ridley)

Scientific name: Lepidochelys olivacea

Family: Cheloniidae

Description

Olive ridley turtles are grey or olive-grey above, usually without any conspicuous markings and whitish below. Their head is large and massive. The carapace (shell) is broad and heart-shaped, usually with six or more costal scales. They can grow to a total length of 1.5m. Their hatchlings are blackish above and dark brown below.

Habitat and distribution

Olive ridley turtles occur in shallow, protected waters, especially in soft-bottomed habitats. They are distributed across the tropics but are rarely found around oceanic islands. Major breeding aggregations occur in Mexico, the west coast of Costa Rica, in Surinam, and the east coast of India. In Australia, they occur along the coast from southern Queensland and the Great Barrier Reef, northwards to Torres Strait, the Gulf of Papua, Gulf of Carpentaria, Arafura Sea and Joseph Bonaparte Gulf in Western Australia. Low density nesting has been recorded at a limited number of sites over recent decades. Within Queensland, breeding is known only from isolated nesting sites at five locations within the Gulf of Carpentaria: Crab Island, Edward River, north of Weipa, Scrutten River mouth and the Wellesley Islands.

Life history and behaviour

No large rookeries of olive ridley turtles have been recorded in Australia. Olive ridley turtles nest all year round, although most nesting occurs during the dry season from April to November. Females lay on average 109 large round, parchment-shelled eggs. Hatchlings emerge from the nests about two months after laying.

Threatening processes

All marine turtle species are experiencing serious threats to their survival. The main threats to the olive ridley turtles are climate change, marine debris entanglement and terrestrial predation of eggs and hatchlings (Cape York population). Other threats include domestic fisheries bycatch and chemical and terrestrial discharge (Northern Territory population).

Recovery actions

A national Recovery plan for marine turtles in Australia exists and identifies the management actions necessary to recover marine turtle species in Australia.

Management to conserve this species include:

• Reduce the impacts from marine debris through improved source reduction, collection and management – particularly ghost nets.
• Minimise chemical and terrestrial discharge through best practice industrial, urban and agricultural run-off and stormwater management
• Reduce impacts of terrestrial predation through targeted predator control programs
• Reduce domestic fisheries bycatch through best practice and continued innovation of turtle bycatch mitigation in all Australian fisheries.
• Invest in climate change research and monitoring programs to assist adaptive management of likely climate change impacts.