Chelonia mydas

Conservation status

International: ‘Endangered’ [World Conservation Union]

Description

Adults: Smooth, high-domed carapace; olive green with occasional brown, reddish-brown or black mottling; carapace length ~ 1.0 m

Hatchlings: Black carapace with white edges; white edges on flippers and plastron

Distribution and habitat

Green Turtles are found in tropical, subtropical and temperate waters around the world. They occur in seaweed rich, subtidal and intertidal coral and rocky reefs and seagrass meadows.

Diet

Immature Green Turtles are carnivorous. As adults they are principally herbivorous, feeding mostly on algae, seagrass, mangrove fruit and jellyfish.

Breeding

Nesting season – Australia: Between October and February in eastern Australia. Hatchlings emerge December to May.

Years between breeding 2-8 years

Average clutch size ~115 eggs

Average hatching success ~85%

Native predators on hatchlings Crabs, herons, dingoes, fish.

Breeding areas – Australia:

Four major breeding areas:

• Southern Great Barrier Reef – 13 major rookeries, including NW Island, Wreck Island, Hoskyn Island, Heron Island, the Coral Sea cays; approx 8,000 females.

• Northern Great Barrier Reef – 5 major rookeries, including Raine Island and nearby cays, Bramble Cay in the Torres Strait; approx 30,000 females.

• Gulf of Carpentaria – in the southeast, 3 major rookeries at Bountiful, Pisonia and Rocky Islands; in the southwest, adjacent to the Sir Edward Pellew Islands

• Western Australia– widely spread major rookeries on NW Shelf, including the Lacepede Islands, north of Broome, Barrow and Monte Bello Islands

Small numbers also nest on the National Nature Reserves in the Indian Ocean.

The proportion of Green Turtles nesting each year varies considerably and is influenced by variations in the El Nino Southern Oscillation (ENSO). They are the only species of sea turtle for which this has been shown, and it may be based on nutrition.

Main threats

Incidental capture in fishing and shark control program gear; ingestion of synthetic material; boat strike; predation of eggs or hatchlings; unsustainable indigenous hunting of adults and collecting of eggs; increased incidence of disease (fibropapilloma).

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