Marine turtles have lived in the oceans for over 100 million years. They are an integral part of the traditional culture of many coastal indigenous peoples throughout the world.
Marine turtles migrate long distances between their feeding grounds and nesting sites. They have a large shell called a carapace, four strong, paddle-like flippers and like all reptiles, lungs for breathing air. The characteristic beak-like mouth is used to shear or crush food.
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, over-harvesting of turtles and eggs, and predation of eggs and hatchlings by foxes, feral pigs, dogs and goannas.
There are only a few large nesting populations of the green, hawksbill and loggerhead turtles left in the world. Australia has some of the largest marine turtle nesting areas in the Indo-Pacific region and has the only nesting populations of the flatback turtle.
Of the seven species of marine turtles in the world, six occur in Pacific waters: Flatback turtle (Natator depressus), Green turtle (Chelonia mydas), Hawksbill turtle (Eretmochelys imbricata), Leatherback turtle (Dermochelys coriacea), Loggerhead turtle (Caretta caretta) and Olive Ridley turtle (Lepidochelys olivacea).
All species of sea turtles are listed as threatened or endangered. Marine turtles appear to have the potential to reproduce abundantly: females can lay hundreds of eggs in one nesting season. But even under "natural" conditions, relatively few young turtles survive their first year of life.
Predators such as crabs, foxes, and birds often kill the hatchlings as they make their way from the nest to the sea, and when they reach the shallows, many more small turtles are taken by fish. When humans harvest turtle eggs, disturb or degrade nesting beaches, the scales become tipped even more heavily against young turtles. It takes decades for surviving juveniles to reach maturity and start to breed, and adult turtles must live to reproduce over many years if the population is to thrive. But escalating mortality on the high seas, in the nets and long-lines of fishing fleets, and from pollution and disease, means fewer and fewer turtles are living long enough to reproduce.