The Great Barrier Reef World Heritage Area contains an estimated 15% of Australia’s known populations of dugongs (Dugong dugon). Although the dugong is listed on the IUCN Red List as ‘Vulnerable to Extinction’, the status of its populations around the Australian coast appears to vary from relatively secure to under threat of disappearing from some regions. The first data indicating a significant decrease in dugong population numbers in the Great Barrier Reef World Heritage Area was in 1992. Dedicated aerial surveys of dugong populations showed that dugong numbers south of Cooktown in 1992 were less than half of those recorded in 1986–87. A follow-up survey in 1994 confirmed this trend, suggesting that the decline was real and not a result of temporary movement of dugongs out of the Great Barrier Reef World Heritage Area. North of Cooktown however, populations remained stable over three separate surveys in 1985, 1990 and 1995.

Sources of pressure on dugong populations are thought to come from habitat degradation and loss, mesh-nets, shark nets set for bather protection, hunting, boat strikes and defence activities.

Concern over the decline in dugong numbers south of Cooktown has led to a voluntary moratorium on hunting of dugongs by a number of traditional owners and other Aboriginal and Torres Strait Islander groups south of Cooktown. Shark nets, which have killed at least 486 dugongs in this region between 1960 and 1996, have also been reduced in number, being replaced by baited hooks in most locations. At the time of writing, shark nets are deployed at eleven locations in the Great Barrier Reef World Heritage Area (near Cairns, Townsville and Mackay).

The most recent management action to protect dugongs from further decline has been the introduction of Dugong Protection Areas (DPAs). In total 16 DPAs were declared in January 1998 (figure 1). The DPAs include seven 'Zone A' areas where most forms of mesh netting are not be permitted and nine 'Zone B' areas where specialised netting practices can continue with modification.

Selection of the DPAs and the determination of their boundaries were on the basis of advice from the Scientific Working Group: an advisory group to the Great Barrier Reef Ministerial Council. The criteria used by the Scientific Working Group to determine these boundaries included the following.

1. Dugong abundance — an area was considered suitable as a DPA if it correlated positively with present high dugong abundance.
2. Seagrass status — the suitability of lower density dugong areas was elevated if it contained seagrass species known to be favoured by dugongs (especially Halophila and Halodule).
3. Size of DPA — the area of DPAs were intended to include most, if not all, of a typical home range as identified in dugong tracking studies at that time.
4. Spacing or regional issues — DPAs were to be spaced so that they could facilitate gene flow, recolonisation of depleted areas and access to remote food sources in the event of local fluctuations.

In providing its recommendations, the Scientific Working Group noted the difficulty it faced in formulating its advice due to the paucity of relevant scientific information. This research strategy arose from the need to: (a) ensure that future management decisions can be made on the basis of better scientific information, (b) assess the effectiveness of the DPAs and dugong management in general, and (c) assist the dugong in its recovery.