Less than 100 dugongs in Sarawak today

Dugong

What do you know about dugongs, also known as sea cows?

In the past, they were often associated with the legend of the mermaids because of their similar silhouettes when swimming in the distance.

According ancient beliefs, dugong tears can cure various diseases and can be used as a love spell.   

The International Union for Conservation of Nature (IUCN) in 2015 said the number of dugongs around the world was declining, that they were extinct in some areas and had placed on the red list for the past 40 years due to the risk of extinction on a global scale.

It is estimated that the dugong population has declined by 20 percent over the past 90 years and they are expected to survive for another 50 years before they disappear totally from this earth.

Long life span

Dugongs are medium-sized marine mammals that have a long-life span of around 70 to 80 years.

Female dugongs reach sexual maturity at six years of age and may have their first calf between the ages of six and 17. Males reach sexual maturity between six and 12 years of age. Because breeding occurs year-round, males are always waiting for a female in oestrous.

The reproductive rate of dugongs is very low and they only produce one calf every 2.5 to seven years, depending on the locations. This may be due to the long gestation period, which is between 14 and 15 months.

Male and female adult dugongs usually can grow to 2.7m long with an average weight of 250 to 300kg while the calf is around 20 to 35kg with a length of less than one metre.

Female dugongs have one calf after a year-long pregnancy, and the mother helps her young reach the surface and take its first breath. A young dugong remains close to its mother for about 18 months, sometimes catching a ride on her broad back.

Dugongs are known as sea cows because they graze on underwater grasses (around 20 to 30kg a day) day and night, rooting for them with their bristled, sensitive snouts and chomping them with their rough lips.

These mammals can stay underwater for six minutes before surfacing. They sometimes breathe by “standing” on their tails with their heads above water.

Dugongs are large, grey brown bulbous animals with flattened fluked tails, like those of whales, no dorsal fins, paddle-like flippers and distinctive head shapes. The broad flat muzzles and mouths are angled down to enable ease of grazing along the seabed.

Their vision is somewhat less clear, causing a relatively slow movement with a maximum speed of around 25km/h over short distances. However, they can dive up to 100 feet or 30m to find food.

Dugongs inhabit tropical waters from East Africa to Vanuatu, about 26 degrees both north and south of the equator; these waters span at least 48 countries and about 140,000km of tropical coastline.  

They live in shallow areas, typically located in protected bays, wide mangrove channels and in sheltered areas of inshore islands. Seagrass beds consisting of phanerogamous seagrasses, their primary source of nourishment, coincide with these optimal habitats.

Dugongs, however, are also observed in deeper water where the continental shelf is broad, neritic and sheltered.

Dugongs use different habitats for different activities. For example, tidal sandbanks and estuaries that are quite shallow are potential areas suitable for calving.

To find out more about this mammal, Suara Sarawak interviewed Sarawak Forest Corporation (SFC) Fauna Research and Conservation (Marine) head James Bali, who has been conducting research on dugongs in the state for more than 20 years.

James Bali in an interview with Suara Sarawak.

Dugongs migrate

According to James, dugongs migrate to find food and to breed.

“They require a large area. If the area has a lot of seagrasses, then that is where the dugongs will be found. If a certain seagrass bed is depleted, they move on to the next one.

“Each dugong has different habits. They like to move individually or in groups of two to three with their own families. 

“So, it can be said that the dugong is an animal with a mysterious personality. It is quite difficult to track their movements and determine the actual number of dugongs in Sarawak,” he said.

Elaborating further, James said, only one species of dugong was found in the state and before 1998, they were considered extinct (in Sarawak) as they were last found in Tanjung Datu to Teluk Serabang before the Second World War, in the 1940s.

“Believe it or not, there are less than 100 dugongs in Sarawak today.

“They may decrease and increase. But it must be remembered that the dugongs are not just ours as they can swim up to hundreds of kilometres moving from the state waters to the waters of Labuan, Sabah, Brunei and maybe even the Philippines.

“Among the countries with high dugong populations are Bahrain, Papua New Guinea, Qatar, United Arab Emirates and Australia.

“The largest dugong population is found in the northern waters of Australia between Shark Bay (Western Australia) and Moreton Bay (Queensland).

“In Southeast Asia, dugongs can be found in Myanmar, Thailand, Cambodia, Vietnam, the Philippines, Indonesia and Malaysia.

“In Sarawak, dugongs are found in Kuala Lawas area near the Gulf of Brunei where the largest stretch of seagrasses bed with an area of 30km is found,” he said, adding dugongs were one of four living species of the order Sirenia, which also included three species of manatees (West Indian Manatee, West African Manatee and Amazonian Manatee).

In Malaysia, dugongs are found in the waters of Johor (Straits of Johor, Teluk Mersing, Pulau Rawa, Pulau Seribuat, Pulau Besar, Pulau Tengah, Pulau Hujung), Sabah (Tawau, Kunak, Lahad Datu, Sandakan, Beluran, Kudat, Semporna) as well as Labuan and Sarawak (Tanjung Datu and Lawas) as these states have a lot of seagrasses.

However, it is reported that there are three to five dugong deaths each year.

“According to a study conducted by Universiti Malaysia Sabah (UMS) undergraduate students in Lawas, a total of 100 respondents who had found dugongs, said that the death rate of dugongs a year was around nine, with most of them caught in fishing nets.

“Of the nine, six died because they were caught in drift nets. The dugongs will drown if they cannot rise to the surface of the water.

“Besides that, these could be due to predators such as stingrays, being hit by ship propellers and so on,” he explained.

Therefore, he said, the SFC, with the collaboration of several agencies, has carried out several research and conservation projects on dugongs and seagrasses in Kuala Lawas.

Further descriptions of these projects will be touched in the next series.

Dugong found caught in a fishing net in Kuala Lawas.

Dugong myths

Some believe that dugongs were the inspiration for ancient seafaring tales of mermaids and sirens.

The term dugong is taken from the Tagalog language, duyung or duyong, which means lady of the sea, based on an old fairy tale about sea creatures in the shape of half human, half-fish.

In the past, the main threat of dugong extinction was due to human hunting for dugong tears. There are still people who believe these tears have mystical values such as bringing them wealth and helping them to seduce women.