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Conservation
AsiaSoutheast Asia

As Chinese-built dams multiply, 1 in 5 Mekong fish species face extinction, report finds: ‘biggest threat is hydropower’

  • Some 19 per cent of the 1,148 or more fish species in Southeast Asia’s longest river are heading towards extinction, according to a new report
  • Proliferating Chinese-built hydroelectric dams upriver have blocked much of the sediment that provides essential nutrients

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An aerial view of the Mekong River at the Thai-Laos border in 2019. Among the river’s fish species facing extinction are 18 listed as “critically endangered” by the International Union for Conservation of Nature. Photo: AFP
Reuters

Unsustainable development threatens the health and diverse fish populations of the Mekong river, with one-fifth of fish species in Southeast Asia’s main artery facing extinction, a report by conservation groups said on Monday.

The Mekong, stretching nearly 5,000km (3,000 miles) from the Tibetan Plateau to the South China Sea, is a farming and fishing lifeline for tens of millions of people in China, Laos, Myanmar, Thailand, Cambodia and Vietnam.

Threats to its fish include habitat loss, conversion of wetlands for agriculture and aquaculture, unsustainable sand mining, introduction of invasive species, worsening climate change and hydropower dams fragmenting the flow of the river and its tributaries, according to the report compiled by the WWF and 25 global marine and wildlife conservation groups.

A fisherman is seen next to a Giant Barb, the world’s largest species of carp, in Tonle Sap, part of the Mekong River system in Cambodia. Photo: Zeb Hogan USAID Wonders of the Mekong/Handout via Reuters
A fisherman is seen next to a Giant Barb, the world’s largest species of carp, in Tonle Sap, part of the Mekong River system in Cambodia. Photo: Zeb Hogan USAID Wonders of the Mekong/Handout via Reuters

“The biggest threat right now, and a threat that’s still potentially gaining momentum, is hydropower development,” said fish biologist Zeb Hogan, who heads the USAID-partnered Wonders of the Mekong, one of the groups behind the report.

Dams alter the flow of the world’s third-most biodiverse river, change water quality and block fish migration, he said.

Proliferating Chinese-built hydroelectric dams upriver have blocked much of the sediment that provides essential nutrients to tens of thousands of farms in the Mekong River Delta, Reuters reported in 2022.

Some 19 per cent of the 1,148 or more fish species in the Mekong are heading towards extinction, said the conservationists’ report, “The Mekong’s Forgotten Fishes”, adding that the number may be higher as too little is known about 38 per cent of the species to gauge their conservation status.

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