Dugong on the Kimberley coast of WA
Dugong or sea cows (Dugong dugon) are large sea mammals, and one of only four species of the order Sirenia. Although Dugong are found in the waters of at least 37 countries in the Indo-Pacific, their main range is the waters off northern Australia, between Shark Bay in Western Austrlaia and Morton Bay in Queensland.
The dugong has a fusiform body with no dorsal fin or hind limbs, instead possessing paddle-like forelimbs used to manoeuvre. Heavily reliant on seagrass as food, the Dugong is largely found in wide, shallow bays such as Roebuck Bay near Broome, mangrove channels, and the lee side of large inshore islands. A 2009 study found Roebuck Bay to be a particularly important location for Kimberley Dugong.
The Dugong is the only strictly herbiverous marine mammal, and its range is limited by the distribution of seagrass species. Although social animals, Dugong are usually found as solitary animals or in pairs, due to the limitations of the seagrass beds to support larger populations of foraging animals. Dugong are most abundant in the marine waters of northern Australia that support the Halodule and Halophyla seagrass species. The animals are estimated to consume 28–40 kg of seagrass per individual per day (Limpus and Chatto 2004).
Dugong have small eyes and limited vision, but acute hearing which aids in navigation and communication in the turbid Kimberley waters. Communication between individuals is through chirps, whistles, barks, and other sounds that echo underwater.
Growing to a length of 3m and weighing approximately 420kg as adults, the animals can live up to 73 years. A Dugong’s body is cylindrical, with two short paddle-like flippers and horizontal tail flukes, similar to a dolphin’s. Short hairs, especially around the mouth, may aid in foraging and navigation.
Dugong dugon is the only extant species of the Dugongidae family, and is listed as Vulnerable under IUCN 3.1. Dugongs have traditionally been hunter for both meat and oil, and some populations are now in danger of extinction. The main dangers to Dugong are hunting, habitat degradation, and fishing-related fatalities.