Mekong River Dam Threatens Four of World's Top 10 Biggest Fish Species

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Photo by Schristia via Flickr CC

A hydropower dam project planned for the lower Mekong River is getting greater attention from conservationists as it nears the final stages of an approval process. The project would cut off the migration route for the Mekong giant catfish, an iconic fish within the culture, severing off the spawning grounds located upriver in northern Thailand and Laos. The species is already critically endangered due to overfishing and poor water quality. The dam would also impact three other species of the world's top ten largest, as well as cut off sediment flow from the river to the delta which provide nutrients to one of the world's most productive regions for fisheries and agriculture. The report, titled River of Giants: Giant Fish of the Mekong, studies the impact the dam will have on four of the largest fish species in the world, which call the Mekong home. They include the Mekong giant catfish, the Giant freshwater stingray, the Giant pangasius (or dog-eating catfish), and the Giant barb.

The report states that Mekong giant catfish populations have plummeted 90% in the last 20 years, and the giant dog-eating catfish is almost never seen anymore in the wild. Their biggest threat to survival now is the hydropower dam projects in the lower Mekong, which stop their migration. If the new dam is built, it could be the final nail in the coffin.

"Like tigers, the giant fish of the Mekong are flagship species, immense in size, unique and culturally significant. Being flagship species also means that as they rely on a number of different habitats and are so vulnerable to changes to the river ecosystem, their status is an important gauge of the health, ecological integrity and sustainable management of the Mekong and its many habitats. Successful management and conservation of these flagship species will therefore also benefit many other species which share similar habitats or face similar threats."

The WWF suggests a delay in the approval of the mainstream dams and instead prioritising dams on rivers that already have hydropower dams developed on them, which would buy time for more thorough impact studies on the Mekong dam project. Right now, there are 11 hydroelectric dam projects planned for the lower Mekong, the impact of which could result in immense boosts in hydroelectric power, but immense damage for these species as well as many others that rely on the delta (including humans, since the delta is known as the "rice bowl" of Vietnam).