Pacific ridley turtle (olive ridley)
Pacific ridley turtle hatchling. Photo: Dr. M Guinea
Common name: Pacific ridley, Olive ridley turtle
Scientific name: Lepidochelys olivacea
Family: Cheloniidae
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and Endangered nationally (Environment Protection and Biodiversity Conservation Act 1999). It is ranked as a critical priority under the Department of Environment and Resource Management Back on Track species prioritisation framework.
Description
Pacific 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 1.5 m. Their hatchlings are blackish above and dark brown below.
Habitat and distribution
Pacific ridley turtles occur in shallow, protected waters, especially in soft-bottomed habitats. They occur across the tropics in distribution 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 nestings 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
Pacific ridley turtle sub-adult. Photo: Col Limpus (DERM)
No large rookeries of Pacific ridley turtles have been recorded in Australia. Pacific ridley turtles nest all year round, although most nesting occurs during the dry season from April to November. Females lay on average about 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 are pollution and changes to important turtle habitats, especially coral reefs, seagrass beds, mangrove forests and nesting beaches. Other threats include accidental drowning in fishing gear and, over-harvesting of turtles and eggs.
Recovery actions
- To conserve current populations it is imperative that major existing feeding and nesting sites are protected so that urban and industrial development can no longer threaten them;
- The control of feral animals and domestic dogs is essential at nesting sites along Queensland's coast to protect eggs from predation;
- Increase public awareness about the effect of light sources around nesting sites and promote the use of alternative lighting and protection of nesting sites to local councils;
- Encourage traditional hunters to comply with harvesting conditions;
- Fishing activities need to be monitored, in particular the use of Turtle Excluder Devices (TEDs) and the need for commercial fishers to check longlines, gillnets and lobster/crab pots frequently to disentangle any turtles caught accidentally.
What can you do to help this species?
- Remembering that rubbish you throw away can find its way to the sea, where turtles can mistake things such as plastic bags for jellyfish. Plastic swallowed by mistake can cause blockages of the stomach and intestines of marine animals such as turtles.
- Being on the lookout to avoid turtles when out in your boat. Many turtles are struck by propellers of speeding boats and this can cause injury and death.
- Following the regulations relating to Personal Water Craft (jet skis, waveriders and waverunners), avoid travelling over seagrass beds and shallow water, staying in the navigation channel when travelling in conservation zones and operating off the plane in "turtle and dugong go-slow areas".
Related information
A Biological Review of Australian Marine Turtles: 1. Pacific ridley turtle Lepidochelys olivacea
Carpentaria Ghost Net Programme
Department of the Environment and Heritage 2005. Protected marine species identification guide. Department of the Environment and Heritage, Canberra.
Environment Australia and Marine Turtle Recovery Team 2003. Recovery plan for marine turtles in Australia. Department of Environment and Heritage, Canberra.
Spotila, JR 2004. Sea turtles. The John Hopkins University Press, London.
Last updated 26 August 2011