Vulnerable Species: The Dugong

The Dugong is a majestic marine mammal that is one of four species in the Sirenia order. As the other three species are Manatees, the Dugong represents the last of the once diverse family of Dungongidae; their closest modern relative, Steller’s Sea Cow, was hunted to extinction in the eighteenth century. As all Manatee use fresh water to some degree, the dugong is strictly speaking the only marine herbivorous mammal.

They are well known as the ‘sea cow’ which is somewhat understandable with their cumbersome size. Reminiscent of a dolphin without the dorsal fin, they propel themselves using their fluked tail and manoeuvre using their paddle-like forelimbs. Their snouts have downturned, an evolutionary trait that has better enabled them to eat their preferred food source of sea grasses.

They can be found in warm coastal waters from the Pacific Ocean to the eastern coast of Africa. Accurate numbers of dugong populations are hard to come by as they are shy creatures that do not approach humans, so it is believed that the current estimate could be lower than the actual total owning to this uncertainty in data. It is known that Australia is home to the largest populations of dugong, with the Great Barrier Reef itself supporting a population of around 10,000, with larger populations spread around the country’s many bays and estuaries.

Dugongs can be long lived, with the oldest known specimen reaching 73 before death. With only a few natural predators which include crocodiles, killer whales and sharks, the dugong is a species that should have been able to proliferate well and maintain a healthy level of population, even including disease and infection that affects the species. In Queensland alone it is estimated that 30% of the dugong that have died since 1996 have died due to disease.

The largest impact on the dugong is, unfortunately, from humans. Like Steller’s Sea Cow, they were seen as easy prey and were hunted for their meat and oil – they are such easy prey as they must surface to breathe quite frequently, an adult only able to hold their breath for up to six minutes at most. They are prone to over-exploitation, as their slow rates of reproduction are not enough to counteract intensive hunting, disease spread or pollutant threats that are killing the sea grasses which the dugong so heavily relies.

To save the dugong we must turn a more economical mind to our oceans and look to preserve those environments where we see less of the effects from our pollutants and other interferences that interrupt how the environment works. Once their habitat has been secured, we should minimise our interactions with the dugong to allow them to re-establish themselves, potentially by increasing the numbers of countries in which the hunting of a dugong is illegal. Whilst it may seem like changing how we affect the environment is a huge deal, if we all aspire to make a little change each day then we should easily meet our goal and help save the dugong.