Common name: leatherback turtle
Scientific name: Dermochelys coriacea
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and nationally (Environment Protection and Biodiversity Conservation Act 1999). It is ranked as a critical priority under the department's Back on Track species prioritisation framework.
The leatherback turtle is the largest marine turtle, growing up to a length of 3m. The carapace (upper part of the shell covering the back of the turtle) of the adult is covered by a thick, smooth, leathery skin and is strongly pointed at the rear. It is usually a uniform dark brown or black above, sometimes with paler marbling on the back or with longitudinal rows of small, fine dots and usually with pale white, pink or cream spots and blotches on the sides. The throat and lower sides of neck are white, pale cream or pink mottled and blotched with dark brown or black and whitish or pinkish-white below. A series of seven prominent longitudinal ridges occur on the carapace (including the outer lateral pair) and four ridges along the plastron. The front flippers are large and lack claws. Breeding males and females are similar in appearance, but males have a longer tail. The Queensland Marine Turtle Field Guide shows how to identify a leatherback turtle.
The hatchlings are black with five distinct ridges on the shell. The average carapace length of a hatchling is 5.8cm and each hatchling weighs about 46g.
Habitat and distribution
The leatherback turtle has the widest distribution of any marine turtle, occurring in tropical, temperate and sub-polar waters from the North Sea and Gulf of Alaska in the Northern Hemisphere, to Chile and New Zealand in the Southern Hemisphere. Leatherback turtles occur in tropical and temperate waters of Australia. Large numbers of leatherback turtles feed off the southern Queensland and New South Wales coasts and off Western Australia's coast, south of Geraldton, but they are less abundant in the tropical waters of northern Australia. The best place in Queensland to see leatherback turtles is Wreck Rock, north of Bundaberg.
Most sightings are along the more heavily populated eastern seaboard of Australia where large adults are found year round in larger bays, estuaries and rivers. The frequency of sightings suggests that the species actively seeks out temperate feeding grounds, rather than simply straying to the south.
Life history and behaviour
Most leatherback turtles found in Australian waters breed in neighbouring countries, particularly in Java and along the northern coast of Irian Jaya, Papua New Guinea and the Solomon Islands. This species is thought to live for at least 30 years or more.
No large rookeries have been recorded in Australia. Scattered nesting previously occurred along the southern Queensland coast from Bundaberg to Roundhill Head and along the coast of Arnhem Land from Coburg Peninsula to Maningrida, including Croker Island. Breeding in Australia occurs mostly during December and January. Females lay on average about 83 large eggs and 47 small yolkless eggs per clutch. Turtle eggs require temperatures in the range of 23-33°C throughout incubation. As with other species of marine turtles, the sex of the hatchlings is determined by nest temperature. Males result from cooler temperatures and females from warmer temperatures.
Leatherback turtles are carnivorous and feed mainly in the open ocean on jellyfish and other soft-bodied invertebrates. Casual observers have seen these turtles feeding on unidentified jellyfishes (apparently Catostylus mosaicus) and on bluebottles or Portuguese Man'o'War Physalia utriculus along the coast of New South Wales. These turtles have a number of adaptations which allow them to venture into cold water to forage for food. These include a large adult body size, a thick layer of fatty tissue and some ability to regulate their temperature to prevent excess cooling. Foraging occurs throughout the water column, from the surface layer to depths of several hundred metres. Deep diving in leatherback turtles is assisted by other adaptations that conserve oxygen, such as the ability to slow their heart rate and to direct blood flow away from non-vital body organs while diving.
Leatherback turtles have been known to sporadically nest in low numbers in Australia but have not been recorded nesting on the east coast since 1996. The main threats to leatherback turtles are climate change, marine debris ingestion, international take and domestic and international fisheries bycatch.
A national recovery plan for marine turtles in Australia identifies the priority management actions necessary to recover marine turtle species in Australia, including:
- Liaise at a regional scale to address and reduce the source of marine debris.
- Promote best practice bycatch mitigation and innovation in all Australian fisheries and continue to meet international obligations including conservation management measures under regional fisheries management organisations.
- Determine genetic affiliations of leatherback turtles nesting in Australia.
- Monitor nesting activity in historically known nesting areas.Raising awareness of marine turtles and involving the community in their protection.
The department also provides turtle biology and conservation training to Indigenous Groups. Indigenous rangers in a number of communities are now collecting turtle monitoring data to help with the conservation of marine turtles.
The Queensland Government responds to stranded marine animals as a high priority, and this work involves active partnerships with volunteer and rehabilitation centres. Information is collected on each stranding event and an annual report on marine strandings is available.
What can you do to help this species
- Report sick, injured, dead and/or tagged marine turtles to the RSPCA Qld on 1300 ANIMAL (1300 264 625). Queensland Government officer in the relevant region will be contacted with your information and will determine the appropriate response.
- 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 turtles.
- Follow the regulations relating to "go slow areas for turtles and dugong" including operating vessels off the plane and not undertaking motorised water sports in these areas. Many turtles are struck by propellers of speeding boats and this can cause injury and death.
- Take care when fishing, don’t leave behind discarded fishing lines and use non-stainless steel hooks.
- Check crab pots regularly. Set your pots to avoid loose rope floating about in the water and ensure your pot entrances are not large enough to trap a turtle. Familiarise yourself with the guidelines on how to make a new crab pot, or learn how to correctly modify an existing one.
Commonwealth of Australia 2017. Recovery plan for marine turtles in Australia. Department of the Environment and Energy, Canberra.
Queensland Parks and Wildlife Service 2016. Queensland Marine Turtle Field Guide . Former Department of National Parks, Sport and Racing, Brisbane.
Department of Environment and Energy, 2017. Dermochelys coriacea Leatherback turtle: in the Species Profile and Threats Database. Department of the Environment and Energy, Canberra.
Limpus, C 2009. A biological review of Australian marine turtles: 6. Leatherback Turtle Dermochelys coriacea (see availability) Former Environmental Protection Agency, Brisbane