China’s Sea Cow Believed to Be ‘Functionally Extinct’: Research Report

An official of the Department of Marine and Coastal Resources hugs Marium, a baby dugong separated from her mother, near Libong island, Trang province, southern Thailand. The baby dugong that has developed an attachment to humans after getting lost in the ocean off southern Thailand is being nurtured by marine experts in hopes that it can one day fend for itself. May 23, 2019. Sirachai Arunrugstichai via AP

A recent study has concluded that the dugong, a marine mammal commonly known as the sea cow, is now “functionally extinct” in China’s coastal waters.

The study by the UK’s National Academy of Sciences was conducted through large-scale interview surveys in the fishing communities along the four Chinese coastal provinces—Hainan, Guangxi, Guangdong, and Fujian. The researchers also collected all available historical dugong records on the dugong in China for analysis.

The research article was published in the peer-reviewed science journal Royal Society Open Science on Aug. 24. It suggests that out of the 788 professional fishermen surveyed, only five percent, or 37 fishermen, reported sightings of dugongs. Furthermore, only three of the sightings occurred within the past five years, and the average last-sighting date was 23 years ago.

The researchers concluded that dugongs in Chinese waters have experienced a dramatic population collapse since 1975 and that this decline is unlikely to be reversed even if some of the species remain in the area, making them “functionally extinct” in China.

According to the research, dugongs in China reached their peak population around the 1960s before starting to decline in 1975, and no evidence of their presence in China has been documented since 2008.

As the only strictly herbivorous marine mammal, the dugong’s main diet consists of seagrass, the beds of which are found in shallow coastal waters. Adult dugongs can consume up to 40 kilograms (88 pounds) of seagrass per day, and average around 3 meters (10 feet) in length and 420 kilograms (926 pounds) in weight.

Dugongs are known for their gentle temperament and long lifespan of around 70 years. However, dugongs are one of the slower marine species, with a typical swimming speed of around 10 kilometers per hour (6 miles per hour) and a top speed of 22 kilometers per hour (13 miles per hour). Additionally, dugongs can only stay underwater for two to six minutes at a time before needing to come up to breathe.

Because their habitat is coastal waters, dugongs have historically been hunted and killed for their meat, skin, teeth, and bones. Additionally, archeological evidence suggests that dugongs were a significant part of the diet of people living close to the Persian Gulf 4,000 years ago.

Researchers believe that hunting, combined with the degradation of seagrass beds and accidental entanglement, may have contributed to the rapid collapse of China’s dugong population.

Researchers also stated that since approximately one-third of the world’s marine mammal species reside in Chinese waters, the degree to which Chinese marine ecosystems have deteriorated over the years, as shown in the functional extinction of dugongs, requires more sustainable regional marine stewardship practices and marine conservation efforts.

However, the good news is that sea cows are not unique to China, as they inhabit the coastal waters of 37 tropical and subtropical countries around the world, from East Africa to Vanuatu in the Pacific.