Great Sandy Strait

Many scientists today believe the myth of the mermaid was inspired by dugongs. The name of the scientific order to which the species belongs—Sirenia—was taken from the word ‘siren’ (for those who don’t know—a beautiful sea creature of classical mythology that looked like a woman and whose song was capable of luring lonely sailors to their deaths).

Dugongs (Dugong dugon) are also—and perhaps more suitably—known as the ‘sea cow’, because, not unlike their land-based bovine counterparts, they are shy and slow moving, and spend their days grazing seagrass beds in warm, shallow waters.

The Great Sandy Strait is recognised as the most important habitat for dugongs in South-East Queensland. But this status will very likely be lost if a dam is built on the Mary River.

Threatened Status

The dugong is an internationally vulnerable species—it is listed as such under the Nature Conservation Act 1992, and as threatened by the International Union for the Conservation of Nature and Natural Resources (IUCN). This is simply because dugongs can only live where there is sufficient seagrass to eat, and seagrass habitats throughout the world are being destroyed by such things as dredging and pollutants being washed into the sea. The dugong is a protected species in Australia, and is only still hunted traditionally by some Aboriginal groups.

Reports indicate there are only around 1700 of the species left on our Great Barrier Reef. There are differing accounts of dugong numbers in Hervey Bay, ranging from 800 to 2000. Some permanently inhabit the area; for others it is a critical migratory habitat. Their numbers have certainly declined in the region largely due to the disappearance of seagrass, but also through accidental drowning in nets and boat strikes. The Hervey Bay-Tin Can Bay Dugong Protection Area covers most of the strait, and the aim of this zoning has been to promote awareness and help the dugong population recover.

Features

Perhaps surprisingly, dugongs are more closely related to hippopotamus and elephants than to other marine mammals like whales and dolphins. They are a large mammal, with an average length of 2.5 metres—although they sometimes reach up to 3 metres—and an average weight of 500 kilograms. Although their skin looks smooth, at close inspection the surface is rough and covered in short, thick bristles. Beneath this skin is a thick layer of fat which gives the animal a chubby appearance. Their tail is broad and forked, not unlike the shape of a whale’s, and the flippers toward the front of their body are small.

Dugongs, like all sea mammals, breathe through their lungs and can spend up to fifteen minutes at a time underwater before surfacing for air. They have large lips which are curled up to breathe easier on the surface. These lips are also useful for tearing off seagrass, of which an adult dugong can consume 30 kilograms in one day, leaving telltale feeding trails through the beds. They are usually found in pairs or small groups and are mainly night feeders.

Females give birth to a single calf only every three to seven years, and after giving birth a mother will nurse and nurture her baby for one to two years—the calf will suckle from a nipple in its mother’s armpit for up to a year and a half. Being mammals, dugong calves suckle milk. A dugong matures at between 10 to 17 years of age and can live for up to 70 years!