Direct threats to dugongs along the urban coast include incidental capture in commercial fishing and shark control program nets (see Section 5.4.3), illegal fishing nets and poaching (see Section 5.4.3), vessel strike, legal take (see Section 5.9) and ingestion of marine debris. Some Traditional Owner groups have voluntarily ceased hunting dugongs along the developed coast in recognition of the pressure this species is under from a range of other threats (see Section 5.9). It is unknown how projected increases in recreational use of the Region will affect dugongs. Management A number of management measures to reduce the direct and indirect impacts on dugongs are in place in the Region, including: • Protection of the species under Commonwealth and Queensland environmental legislation for example, ‘listed migratory species’ under the Environment Protection and Biodiversity Conservation Act; ‘protected species’ under the Great Barrier Reef Marine Park Regulations; ‘vulnerable’ under the Queensland Nature Conservation Act. • Spatial protection of coastal and some estuarine areas through zoning plans, trawling closures, Dugong Protection Areas and Queensland Fish Habitat Areas. • Traditional Use of Marine Resources Agreements and Indigenous Land Use Agreements. • Improvement of water quality that enters the Region through the implementation of Reef Plan. • Implementation of a dugong and turtle protection plan from July 2014, under the Australian Government’s Reef Trust. • Voluntary vessel ‘go-slow’ transit lanes in important dugong habitat in the Hinchinbrook area. Since the Outlook Report 2009, based on evidence provided by the Marine Wildlife Stranding program, specific regulations were enacted to address deaths to dugongs from commercial nets in Bowling Green Bay. Knowledge about the Region’s dugong population continues to provide evidence for its condition. Specific programs include: the Sightings Network component of Eye on the Reef where dugong observations by community members and others are collected135; the Marine Wildlife Strandings program reports on dugong strandings and causes of mortality136; and regular aerial surveys to estimate dugong populations along the urban and remote coasts137,138,139,140. Evidence for recovery Population modelling suggests that even with the most optimistic combinations of life history parameters (for example, low natural mortality and no human-induced mortality), the dugong population is unable to increase by more than four to five per cent per year.141 The Outlook Report 2009 reported that the urban coast dugong population may take more than a century to recover and is subject to many continuing pressures. Dugong mortalities recorded by the Marine Wildlife Strandings program in 2011 were the highest since the commencement of the publication of the program’s annual reports in 1998. The 2011 aerial survey results for the urban coast of Queensland showed the lowest recorded presence of dugongs since the surveys began in 1986 (see Figure 2.15).137 This is in contrast to the previous survey in 2005, when the population was considered to have stopped declining.137 The recovery of dugong populations is strongly dependent on the condition of seagrass meadows, their primary food source, and reducing direct mortality, such as from incidental catch, marine debris and boat strike. Reducing fecundity is one response by dugongs to reduced habitat quality (available seagrass).133,142 Significant losses of seagrass habitats were recorded following higher than average rainfall (and associated flooding) during the summer of 2010–11 and the category five cyclone Yasi in 2011.143 The effects of these events were compounded by a number of previous years of extreme weather including cyclones and freshwater flooding.144,145,146,147,148
Urban coast dugong populations are the lowest since surveys began.
8.3.7 Humpback whales