Researchers from Zoological Society of London (ZSL) have declared a mammal related to the manatee, extinct in China.
Only three people surveyed from coastal communities in China reported seeing the dugong in the past five years, reports BBC.
Known as the ocean's most gentle giant, the dugong's slow, relaxed behaviour is likely to have made it vulnerable to overfishing and accidents due to shipping.
It still exists elsewhere in the world but is facing similar threats.
Prof Samuel Turvey, from ZSL, who co-authored the research study, said, "The likely disappearance of the dugong in China is a devastating loss."
Scientists at ZSL and the Chinese Academy of Science reviewed all historical data on where dugongs had previously been found in China.
They found there had been no verified sightings by scientists since 2000.
In addition, the researchers turned to citizen science to interview 788 community members living in those coastal regions identified, to determine when local people had last seen Dugong.
On average, residents reported not having seen the animal for 23 years. Only three people had seen one in the past five years.
This has led the researchers to declare the dugong functionally extinct, meaning "it is no longer viable... to sustain itself", said Heidi Ma, postdoctoral researcher at ZSL.
The dugong is a unique character of the sea. Weighing in at almost half a tonne, it is the only vegetarian marine mammal.
Bd-pratidin English/Tanvir Raihan
