Pour one out for the dugong today — the bulbous yet endearing undersea mammal has hit a worrying new benchmark of species decline. Scientists have declared the animal “functionally extinct” in part of the South China Sea, in a study published in the journal Royal Society Open Science. Hunting, the fishing industry, aquaculture, and other human activity that’s degraded the seagrass habitat is to blame, according to the researchers.
Dugongs are the last surviving species in their scientific family; their closest living relatives are manatees. They are thought to have been the inspiration for some of the Pacific’s mermaid mythology. (Though the Pokémon Dewgong was probably named after the real-world dugong, the animated critter seems to have more in common with seals.) Dugongs also the world’s only known marine mammal to be exclusively vegetarian, as even manatees have been recorded occasionally eating fish. The gentle seagrass grazers live and breed in the tropical and sub-tropical coastal waters of multiple regions, from East Africa and the Middle East into the South Pacific.
Now though, these singular “sea cows” seem to be swimming around in one less region, according to the study authors. By designating dugongs functionally extinct there, the scientists are saying the species is no longer able to reproduce and maintain a long-term population in the area.
The research team — composed of scientists from the Chinese Academy of Science, England’s Zoological Society of London, and Aristotle University in Greece — reported that records of dugongs in the waters along the southernmost coast of China have declined sharply over the past 50 years. Notably, they wrote, there are no documented records of dugongs in the area after 2008, and there are no “verified field observations” of the mammal after 2000. It’s “the first reported functional extinction of a large vertebrate in Chinese marine waters,” they added.
To come to this dismal conclusion, the study authors reviewed the historic records. They also worked with a team of volunteers and interviewed 788 local fishermen. Only 5% of those surveyed reported ever having seen a dugong in the wild, and only three responded that they’d seen one in the past five years, though those reported sightings couldn’t be verified. The scientists also noted that two of those three recent sightings occurred in an area lacking the seagrass beds necessary to support dugongs and that the individuals may have been drifters from the Philippine population.
“We acknowledge the possibility that a few surviving dugongs in Chinese coastal waters might have been undetected by respondents,” wrote the researchers. “However, our comprehensive assessment suggests that even if some individual dugongs still remain in Chinese waters, the dramatic population decline experienced by the species in recent decades is highly unlikely to be halted or reversed under current conditions.”
Habitat decline, seagrass loss, and hunting are likely to blame for the species’ disappearance, according to the scientists. Previous research has noted that fishing and fish farms have degraded critical seagrass ecosystems in the northern South China Sea. And globally, an estimated 7% of seagrass habitat is being lost every year, according to a 2020 UN report.
And the researchers reported that, between 1958 and 1976, 257 dugongs were killed in the northern South China Sea for food. Records cited by the scientists also indicated the animals are often caught and killed as fishing industry bycatch.
Dugongs are listed as globally vulnerable to extinction by the International Union for Conservation of Nature (IUCN), and are they legally protected in many countries. Individuals can live for more than 70 years, but the species breeds slowly, making their recovery and protection extra challenging.
Though dugongs live on in other places, the disappearance of this unique species from one area is a sobering reminder of how easily and silently extinction can progress. “The message is alarming,” wrote the study scientists. It’s a reminder that “effective population and habitat management are critically needed within dugong habitats elsewhere.”