Small dams threaten fish species on the Mekong River

According to the latest research published by US scientists, plans to build hydropower dams along small tributaries of the Mekong River could cause unmatchable harm to millions of people who depend on fish stocks. in Southeast Asia's longest river.

Projects to build 11 large dams along branches of the 4,600-kilometer Mekong River flow through the territory of China, Myanmar, Laos, Thailand, Cambodia and Vietnam, which are currently of great interest to international scientists.

In December, ministers of Cambodia, Thailand, Vietnam and Laos postponed the decision on the first dam, the Xayaburi dam valued at $ 3.8 billion in Laos, due to environmental concerns.

However, a new international study published in the Proceedings of the US National Academy of Sciences, examining the effects on dam construction on many tributaries of the Mekong, warned of a "catastrophic" future .

Some dam projects may prevent more than 100 species of fish from swimming upstream

'We have found that 78 dams that are about to be completed in the tributaries of the Mekong have not yet been analyzed, which will affect the catastrophe of fishery production and biodiversity ,' 'the study said. Save writing.

Since this area is the area of ​​many migratory fish species, the study found that some dam projects could prevent more than 100 species of fish swimming upstream, causing great losses in biodiversity and fish stocks. river.

Tens of millions of people living in impoverished rural areas along the Mekong River depend heavily on fish as their main source of protein, according to scientists at Cambodia's Freshwater Fisheries Research and Development Institute, as well as Stanford and Princeton University.

'We found that there was a big trade-off between creating energy and influence on the food chain as well as biodiversity ,' the research leader, Guy Ziv of Stanford University told AFP.

Ziv said scientists focused on 27 of the 78 hydroelectric dam projects in the tributaries of the Mekong, because 27 projects are planned to be built in the period 2015-2030.

In addition, these dams also need an international agreement to be built, although it will certainly affect fish species in countries without dams.

'The overall impact of these dams is greater than some of the dams in the main section of the river that have attracted international attention in the past time ,' Ziv said.

'The most profitable country could be Laos, producing energy to export to Thailand and Vietnam, while the bad effect will happen to Cambodia and partly to Vietnam when losing a large amount of fish.'

The researchers said that every year, fishermen in Cambodia and Vietnam alone capture more than one million tons of freshwater fish from the Mekong River and the entire river basin is home to about 65 million people, two-thirds. many of which rely heavily on fisheries.

In total, the researchers identified 877 fish species in the Mekong basin, 103 of which could be threatened if unable to migrate due to the construction of hydropower dams. In particular, there are four dams that can cause heavy losses to fish stocks, including the Se San 2 dam in Cambodia, which can cause fish stocks to drop by 9.3%. Followed by the dams in Laos, Se Kong 3d (2.3%), Se Kong 3u (0.9%) and Se Kong 4 (0.75%).

Although the figure seems small, Ziv says the effect will be more serious when other species rely on these fish in the food chain and 1% of the fish lost is equivalent to 10,000 tons of food.