A conservation strategy for dugongs: implications of Australian research

The dugong (Dugong dugon) is listed as vulnerable to extinction at a global scale. It has a large range that spans some forty countries and includes tropical and subtropical coastal and island waters from east Africa to Vanuatu. A significant proportion of the world’s dugongs is found in northern Australian waters where most modern dugong research has been conducted. Dugongs are long-lived animals with a low reproductive rate, long generation time, and a high investment in each offspring. Population simulations indicate that even with the most optimistic combinations of life-history parameters (e.g. low natural mortality and no human-induced mortality) a dugong population is unlikely to increase by more than 5% per year. Dugongs are vulnerable to anthropogenic impacts because of their life history and their dependence on seagrasses that are restricted to coastal habitats. Even a slight reduction in adult survivorship as a result of habitat loss, disease, hunting or incidental drowning in nets can cause a chronic decline in a dugong population. The optimum management strategy is to identify areas that consistently support large numbers of dugongs and to set these aside as dugong sanctuaries in which dugong mortality is minimized and their habitat protected.