Populations of three endangered turtle species in Hong Kong have declined drastically, a study has found, with researchers warning they could become extinct within three to five years if wildlife trafficking is not brought under control.

Researchers from Lingnan University published their findings on Tuesday, noting the city was the last stronghold in the world for the three species of freshwater turtles.

The golden coin turtle and big-headed turtle are considered critically endangered, with their global population having dropped by 80 per cent or more, while the number of Beale’s eyed turtles has fallen by an estimated 50 to 70 per cent.

A golden coin turtle. No golden coin turtle hatchlings were found during the survey.

“Wild freshwater turtles have disappeared across most of mainland China,” said Jonathan Fong, an assistant professor of conservation science at the university.

“The small populations that remain in Hong Kong represent a unique opportunity for conservation collaboration across the Greater Bay Area.”

The bay area refers to the central government’s scheme to integrate Hong Kong, Macau and nine southern Chinese cities into an economic and business hub.

The researchers released their findings on World Turtle Day, which aims to help raise awareness of the urgent need to protect the animals as their habitats diminish.

The university carried out distribution surveys and population detections at about 100 sites across the city that could be habitats for the turtles, such as country parks, rivers and streams.

Sung Yik-hei, an assistant herpetology professor at the university, said no golden coin turtle hatchlings were found during the survey.

Professor Sung Yik-hei holds a golden coin turtle (left) and a beale’s eyed turtle.

He said the species could have become functionally extinct in Hong Kong, meaning the surviving turtles were no longer viable and able to play a role in the city’s ecosystem.

At nearly 90 per cent of the study sites, there were either no sightings of the wild big-headed and Beale’s eyed turtles or only one was detected, down from a few dozen when the project started in 2009.

Poachers and turtle traps were found in all the study sites using infrared cameras, Sung added.

“There could be only several hundred adult big-headed turtles and fewer than a hundred adult Beale’s eyed turtles left in the wild in Hong Kong,” he said. “If the current hunting activities continue, Hong Kong’s freshwater turtle population could become extinct within three to five years.”

Researchers observed a “drastic decline” in the populations of the three species over the past five years. Sung said that could be due to an increased interest in the turtles as food or pets.

Such shelled reptiles, especially the golden coin turtle, are believed to have healing and aphrodisiac properties in Chinese folk medicine. They are usually consumed as soup or gelatin dessert.

Sung explained that the turtle population had faced difficulties recovering from poaching, because the animal’s reproductive rate was low and they needed at least eight years to reach sexual maturity.

Michael Lau Wai-neng, the executive director of the Hong Kong Wetlands Conservation Association, said: “These small populations are probably among the most robust populations across Asia.

“Protection of the freshwater turtle population in Hong Kong is of global importance.”

Earlier this month, several NGOs, academics and legal experts penned a letter to the city government to highlight their concerns about wildlife poaching.

Co-author Sophie Le Clue, of environmental group ADM Capital Foundation, said: “Urgent action is essential to strengthen investigation, enforcement and deterrent of wildlife poaching. Otherwise, the imminent extinction of freshwater turtles in Hong Kong is inevitable.”

The letter suggested establishing an operational protocol between the Agriculture, Fisheries and Conservation Department and police, setting up an anti-poaching enforcement unit to carry out regular, targeted night patrols and a revision of present legal shortcomings.

The department said it was examining the feasibility of the measures proposed in the letter. It added it planned to work with city experts to draw up an action plan to protect the turtle populations.