Dugong

The Dugong is a large, grey brown bulbous animal with a flattened fluked tail, like that of a whale, no dorsal fin, paddle like flippers and distinctive head shape.

Identification

The Dugong is a large, grey brown bulbous animal with a flattened fluked tail, like that of a whale, no dorsal fin, paddle like flippers and distinctive head shape. The broad flat muzzle and mouth are angled down to enable ease of grazing along the seabed. Eyes and ears are small reflecting the animal's lack of reliance on these senses.

Habitat

Dugongs prefer wide shallow bays and areas protected by large inshore islands. Vagrant animals will occasionally appear as far south as southern New South Wales and near Perth in Western Australia.

Distribution

The Dugong is found over a broad range of the coastal and inland waters of the western Indo-Pacific region. In Australia, they occur in an arc from Moreton Bay in southern Queensland across northern Australia to Shark Bay in northern Western Australia.

Feeding and diet

Dugongs are herbivores, feeding exclusively on seagrasses, cropping the leaves and roots by using their broad muzzle to move the food into the mouth. Dugongs tend to occur in groups or herds and their movement over an area can be followed by the sand plume disturbances to the sea floor.

Life history cycle

Like their relatives, the manatees of the Americas, female Dugongs in season attract the attention of a number of males, one or two of which will eventually mate with her. One young is born after a gestation period of 12-14 months and will continue to suckle from the mother for about 18 months. They may remain with the female for a number of years, as she will not calve again for periods of between 2.5 to 7 years. This low reproductive rate has implications for their conservation worldwide and leaves them vulnerable to dramatic declines due to the impact of human activities.

Conservation status

Dugongs are considered relatively abundant in Australian waters where they are legally protected by all States and the Commonwealth. Their populations are not so secure in other parts of the world and they are listed as vulnerable by the International Union for the Conservation of Nature (IUCN) and protected by the Convention on International Trade in Endangered Species (CITES).

References

• Reynolds, J.E. and Odell, D.K. 1991. Manatees and Dugongs. Facts on File. New York, USA, and Oxford, United Kingdom.
  Marsh, H. (ed.) 1981. The Dugong. James Cook University, Townsville, Australia.
  Bryden, M., Marsh, H. and Shaughnessy, P. 1998. Dugongs, Whales, Dolphins and Seals. A guide to the sea mammals of Australasia. Allen & Unwin, St Leonards, Australia.