Green turtle
Chelonia mydas.
The conservation status of the green turtle, Chelonia mydas is:
- Nature Conservation Act 1992: Vulnerable
- Environment Protection and Biodiversity Conservation Act 1999: Vulnerable
- IUCN Red List of Threatened Species: Endangered.
General information
Green turtles can be found throughout the tropical and subtropical Pacific, Atlantic and Indian Oceans in the coastal waters of at least 140 countries. There has been some debate among scientists whether the 'black' green turtle in the East Pacific is in fact a separate species, being darker, smaller and having a different shaped carapace. Recently the argument appears to have been put to rest as DNA data and skull morphology studies indicate that the populations are too similar to be considered different species.
Australia's Raine Island has one of the largest green turtle nesting populations in the world with around 18,000 females nesting in a single season. Female greens can lay between one and seven clutches in a season, although most commonly three with an interval between each of 12-14 days. On average a clutch contains 110 eggs and the female rarely returns the following year but may wait as long as four to seven years before nesting again.
In undisturbed nests Green turtles have a high hatching success (up to 90%) and hatchlings enter the sea as omnivores, eating almost any food they encounter small enough to eat. In Australia young Greens stay at sea until they are around 35cm long when they move into shallower seagrass areas. Some juveniles in the southern Great Barrier Reef have been recorded in the same feeding grounds for more than 20 years.
While Moreton Bay is an important green turtle feeding ground due to the abundant seagrass meadows, the region is not an important breeding area, with only occasional greens nesting within the boundaries of the Moreton Bay Marine Park.
Further reading
Limpus, C. (1980) in Limpus, C.J., Couper, P.J., Read, M.A. (1994) "The green turtle, Chelonia mydas, in Queensland: population structure in a warm temperate area", Memoirs of the Queensland Museum 35:139-154