Dugongs in Australian waters | wwf

Dugongs in Australian waters

Northern Australian waters between Shark Bay, in Western Australia, and Moreton Bay in Queensland contain most of the world’s remaining dugongs (about 85,000 individuals1). This is likely to represent at least three-quarters of the global population, so our waters comprise a vitally important stronghold for this species.

The second-largest dugong population occurs in the Arabian Gulf, where about 7,000 remain2. Elsewhere, populations are small and fragmented and in some areas, such as Mauritius, the Maldives and parts of Cambodia and Laos, dugongs may already have become extinct3.

Dugongs on the Great Barrier Reef

The Great Barrier Reef region supports globally significant dugong populations and this was one of the reasons behind its World Heritage listing4.

Aerial surveys of dugong populations commissioned by the Great Barrier Reef Marine Park Authority (GBRMPA) have been carried out by James Cook University since 1984. North of Cooktown, population estimates have ranged from 7,000–10,000 individuals. South of Cooktown, the population is estimated to be 10% of what it used to be during the mid 19th century5 – less than 5,000 individuals6.

Dugongs in Western Australia and the Northern Territory

Aerial surveys between 1980 and the 1990s counted about 10,000 individuals in the large Shark Bay dugong population. Another 1,000 were living within the Ningaloo Marine Park and Exmouth Gulf.

However, subsequent surveys showed changes in dugong distribution. The population in Shark Bay had increased to 14,000 individuals and less than 200 remained in Ningaloo and Exmouth Gulf. This shift is thought to have been caused by Cyclone Vance, which hit Exmouth Gulf in 1999.

In the Northern Territory, from Daly River to Millingimbi, about 13,000 dugongs are resident. A further 8,000 ply the waters between Limmen and east of the Sir Edward Pellew Groups of Islands, and 4,000 are thought to live in Blue Mud Bay.

1. Marsh & Lefebvre, 1994
2. al-Ghais & Das, 2001
3. Bryceson, 1981; Marsh & Lefebvre, 1994; Marsh et al., 2001
4. http://www.gbrmpa.gov.au/corp_site/key_issues/conservation/natural_values/dugongs
5. MarshH., Dea’th G., Gribble, N. & Lane, B. 2005. Historical marine population estimates; triggers or targets for conservation? The dugong case study; Ecological Applications 15: (2) 481-492
6. Great Barrier Reef Outlook Report 2009