Natural factors such as predators, old age, cyclones and disease have always caused deaths of marine wildlife. In addition, Indigenous people have hunted marine resources including dugongs and marine turtles in the Great Barrier Reef region for thousands of years. In a natural balance, sufficient numbers of animals survive to replace those that die, which maintains the population. When the number of deaths is greater than the number of animals surviving to adulthood and breeding, the population declines. As dugongs and turtles are long-lived and slow-breeding, any population decline will require many, possibly hundreds, of years to recover.

Changes in human activities in the past 100 or so years have created new causes of mortality in marine wildlife and have increased the number of dugongs and turtles dying, thus threatening the survival of their populations. Australian marine wildlife and that of nearby countries is now under threat from a combination of human-related factors, such as habitat degradation and habitat loss, incidental take in fishing nets and subsistence and commercial harvesting.

For many Great Barrier Reef species, there is insufficient information to assess the status of their populations. Over 40 species in the Great Barrier Reef World Heritage Area are listed as threatened under various legislation. Refer to Tables 1-6 in Fauna and Flora of the Great Barrier Reef World Heritage Area.

Two of the most threatened species on the Great Barrier Reef are the dugong and the loggerhead turtle. Dugong numbers in the southern Great Barrier Reef, south of Cooktown, appear to be about three per cent of that present in the early 1960s. Human related threats implicated in this decline are loss and degradation of seagrass habitat, incidental catch in large mesh nets (commercial, traditional, shark nets at bathing beaches, illegal), Indigenous hunting, illegal take and boat strikes.

All six species of marine turtles in the Great Barrier Reef are threatened. Most threatened is the loggerhead turtle population, which breeds in the southern Great Barrier Reef and southeast Queensland and has declined by up to 90 per cent since the 1960s. The primary threats that have caused this decline include depredation of nests by foxes and incidental capture in fisheries gear.

Action is underway to prevent further declines in dugong and turtle numbers in Queensland and Torres Strait waters including the Great Barrier Reef Marine Park. The threats are being addressed in a systematic and coordinated way that will benefit marine wildlife, their habitats and the health of the marine environment.

To implement these actions the Great Barrier Reef Marine Park Authority (GBRMPA) is working with various management agencies including the Commonwealth Department of the Environment, Water, Heritage and the Arts, the Environmental Protection Agency/Queensland Parks and Wildlife (EPA/QPW), and the Queensland Department of Primary Industries and Fisheries (DPI&F), interest groups including local governments, Aboriginal and Torres Strait Islander people, commercial and recreational fishermen, conservation groups and local communities.

• Management
• Education and information
• Research and monitoring
• Boatstrikes
• Climate change
• Defence activities
• Disease
• Dredging
• Feral animals
• Fishing
• Habitat degradation and disturbance
• Pollution and marine debris
• Traditional Use of Marine Resources