Australia State of the Environment Report 2001 (Theme Report)
Australian State of the Environment Committee, Authors
Published by CSIRO on behalf of the Department of the Environment and Heritage, 2001
ISBN 0 643 06751 5
Australia's marine reptiles include sea snakes, turtles and the Saltwater Crocodile. Of the 30 species of sea snakes, 15 are endemic. While one family inhabits reefs, with many located in the Great Barrier Reef Marine Park, a second group inhabits inter-reef areas and is more likely to be caught by prawn trawling.
Turtle populations in Australian waters are not known with any confidence due to their migratory nature (Figure 10). This also makes them susceptible to pressures in international waters and in Australian waters and is reflected in their listings under several international conventions.
Figure 10: Distribution of turtles.
Source: Environment Australia (2000)
Six of the world's seven species of turtles breed in Australia. The eastern Australian stock of Loggerhead Turtles (Caretta caretta), breeds almost exclusively in the southern Great Barrier Reef region and is considered to be endangered. Its nesting population has declined by 70 to 90% since the 1970s, from about 1000 to about 300. Fox predation of eggs and hatchlings and mortality due to fisheries interactions are thought to have contributed most to the decline.
Three genetic stocks of Green Turtle (Chelonia mydas) breeds in Queensland locations, in the southern and the northern Great Barrier Reef regions and the Wellesley group of islands. The estimated breeding population on the Wellesley group is between 2000 and 7000 females. There are signs that the southern Great Barrier Reef stock may be in the early stages of decline.
Green Turtles eat algae and seagrasses.
Source: G Carter, Great Barrier Reef Marine Park Authority
Australia is the stronghold for Flatback Turtles (Natator depressus), but they are also found in Papua New Guinea and Indonesia. The Hawksbill Turtle (Eretmochelys imbricata), internationally 'critically endangered', has its last stronghold in the northern Great Barrier Reef region, where there is an annual nesting population of several thousand females.
Pressures on turtles arise from their being caught as bycatch in prawn fishing and other fishing activities. Queensland studies suggest that about 5000 turtles are caught accidentally by the East Coast Trawl Fishery per year and 5700 by the Northern Prawn Fishery (EPA 1999b). However, over 90% of these are estimated to be released alive and are assumed to be unharmed.
They are also traditionally hunted by Indigenous people and this hunting is regulated by permits. It is estimated that 2000 to 4000 Green Turtles are caught by Indigenous people per year (Caton and McLoughlin 2000).
All species are protected in Australia under Commonwealth and State legislation. All six of the species are protected under the EPBC Act 1999, and a draft (as at May 2001) National Recovery Plan for Marine Turtles has been prepared. A nomination for otter trawling as a threatening process for marine turtles under the EPBC Act 1999 was (as at February 2001) being considered.
Bycatch Action Plans for two Commonwealth-managed fisheries have been prepared. The use of turtle exclusion devices (TEDs) in the Northern Prawn Fishery from 2000 is mandatory. In 2000, turtle exclusion devices were made compulsory for the entire Great Barrier Reef Marine Park and Hervey Bay for all trawling, with the exception of scallop and deep-sea trawling. Large areas of the Park are closed to trawling, and the number of boats in the trawl fishery has been reduced. From mid 2001, turtle exclusion devices have been mandatory for scallop and deep-sea trawling.
Early indications from a Fisheries Research and Development Corporation project by the Bureau of Rural Sciences, CSIRO, the Australian Fisheries Management Authority and the Northern Prawn Fishery fishing industry are that turtle catch and mortality rates in the Northern Prawn Fishery have decreased significantly since the introduction of TEDs (C. Robins pers comm.).
The fishing industry in Queensland has developed a voluntary code of ethics with respect to the capture of turtles, first adopted in 1994 by the East Coast Trawl Fishery. The Australian Seafood Industry Council has released a manual on reducing bycatch. It is expected that the catch of turtles should significantly decrease in the future.
In some areas, Indigenous Councils have been established by communities to regulate turtle and Dugong hunting in their regions with the support from the Great Barrier Reef Marine Park Authority (GBRMPA). The Guugu Yimithirr peoples of Hopevale north of Cooktown, have produced a management plan for turtles and Dugong and embarked on a major research project with James Cook University scientists focussed on a sustainable harvest.
Within the Great Barrier Reef region, important turtle nesting sites have been protected against human interference, but predation by feral animals is more difficult to control.
States are also addressing turtle conservation through:
- a marine turtle management plan, operating since 1985 in Western Australia,
- the commercial development of Hawksbill Turtles though captive husbandry in the Northern Territory, and
- the protection of the most significant breeding sites for turtles in eastern Queensland.