Declared functionally extinct in China just three years ago, the dugong — a marine mammal famously associated with mermaid legends — has been sighted again in the nearshore waters of the South China Sea.

After a month of tracking an unidentified “big fish,” Chinese marine experts confirmed last week that a large animal spotted near Yongshu Reef along Nansha Islands, an archipelago in the South China Sea, is a dugong, state broadcaster CCTV reported.

Patrol teams first reported sightings in July. Since then, researchers have gathered photos and videos as evidence.

Unlike most dugongs, which travel in small family groups of two or three, this individual appeared alone, prompting calls for further monitoring.

The discovery marks the first confirmed dugong sighting in the Chinese mainland since 2008, when a carcass was found off the island Hainan province.

In 2022, researchers from the Zoological Society of London and the Chinese Academy of Sciences declared the species functionally extinct in China — meaning too few remained to sustain a viable population.

Dugongs are among the oldest marine mammals, with a history dating back 50 million years. Considered marine megafauna, they can grow up to three meters long and weigh up to 450 kilograms. Dugongs primarily inhabit shallow waters of the Indian Ocean and western Pacific, where they feed on seagrass, playing a crucial role in maintaining the health and biodiversity of coastal ecosystems.

The species is currently listed as vulnerable on the International Union for Conservation of Nature’s Red List of Threatened Species and is under Grade 1 protection in China — the country’s highest.

The news came after sightings of two other endangered species — hawksbill and green sea turtles — at Yongshu Reef over the past six months. It also marks the first scientific footage of a live dugong in the Nansha Islands and the central South China Sea in nearly 30 years, filling a crucial gap in the region’s species records, marine experts said.

Song Xingyu, a researcher at the South China Sea Institute of Oceanology, told CCTV that green sea turtles depend on beaches for nesting, while hawksbill sea turtles rely on coral reefs. Dugongs, he added, signal healthy seagrass ecosystems.

“The sightings of these three species at Yongshu Reef highlight the unique ecological value of the reef and demonstrate the significant achievements of China’s ecological construction and protection efforts in the area,” he told Sixth Tone.

Editor: Marianne Gunnarsson.

(Header image: VCG)