ABSTRACT
The dugong (Dugong dugon) is a herbivorous marine mammal that occurs in, but is not restricted to, the GBRWHA, including the nearshore waters of the Great Barrier Reef which are considered to be one of the species’ strongholds (Marsh et al., 2002, 2005, 2011). The dugong is listed as vulnerable to extinction due to various factors, including variations in seagrass availability, incidental drowning in shark nets set for bather protection, accidental by-catch in commercial gill nets, vessel strikes, habitat loss and over-fishing (IUCN, 2013). Since the animal is long-lived and slow-reproducing, with considerable investment in each dugong calf, the species is vulnerable to over-exploitation by humans. Consequently, the maintenance of dugong numbers, and the recovery of depleted dugong populations, is now difficult to achieve. Furthermore, dugongs are highly mobile animals that sometimes migrate across large distances, and in remote waters, with the result that impacts on dugongs are difficult to detect and assess (Marsh and Lawler, 2001; Marsh et al., 2004). Some previous assessments of the magnitude of European impacts on marine wildlife species, including dugongs, have been based on relatively uncritical use of secondary sources; those studies have been challenged recently on the basis of modern scientific methods and improved understanding of the ecology of marine mammals. Given the current conservation threats to dugongs, there is a need to use historical sources more critically to reconstruct the operation and likely impacts of the human activities that exploited those animals (Marsh et al., 2005).
