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About Dugongs

The Dugong 

Family: Dugongidae

Genus: Dugong

Species: Dugong dugon (Müller, 1776) 

The dugong (Dugong dugon) is the only herbivorous mammal that is strictly marine and it is the only extant species of the Family Dugongidae, Order Sirenia. 

This species is a seagrass specialist and its historical distribution has been broadly coincident with the distribution of the tropical Indo-Pacific phanerogamous seagrasses (Potamogetonaceae and Hydrocharitaceae).

Life History 

The dugong is a highly specialized and large-sized mammal (e.g. adults can grow up to 3,5m long and weight up to 400kg). This species is also long-lived, with an average lifespan of 50-60 years, with low rates of mortality as individuals mature. 

Being a k-strategist the dugong has a low reproductive rate, producing a calf every 2.5 to 5 years, after a gestation period of 14 months. They also present high levels of parental care (e.g. lactation may last for 1 year and a half) and a long generation time (about 30 years) population.

Dugongs in East Africa 

Historically were plentiful in the Western Indian Ocean and ranged from Somalia in the north, through Kenya, Tanzania and Mozambique, and off the islands of the Comoros, Seychelles, Madagascar and Mauritius. 

Almost three decades of research in the region suggest that dugongs are now reduced to scattered remnant populations. Past surveys and anecdotal information suggest that although most populations in the region appear to have suffered a steep decline since the 1960s, dugongs may still occur in the coasts of Mozambique, Tanzania and Kenya. They were considered locally extinct in the Mascarene Islands of Mauritius and Rodrigues. 

Research in Mozambique, Tanzania and Kenya are currently being carried out to determine the status of the dugongs in East Africa. 

Threats to Dugongs 

Due their dependence on shallow water seagrasses for foraging, dugongs are usually restricted to the coastal zones, where they are frequently exposed to a number of antropogenic threats, such as hunting, incidental drowning in nets, boat strikes, pollution, sand mining and oil and gas exploration. An increase in adult mortality resultant from human-induced impacts or habitat loss, can lead to a chronic population decline. 

These pressures combined with their life history make the dugong a species extremely vulnerable to over-exploitation and extirpation from several areas of its range.