Proposed dams along Mekong River threaten migratory fish

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An international study on the impact of a plan to build 11 dams along the Mekong river has warned of catastrophic consequences to fish biodiversity in the area.

The study found used modelling to estimate the loss in fish biodiversity that would come from the proposed construction of 27 hydropower dams on the tributaries of the Mekong River, scheduled to begin in 2015.

They found that dams placed in the tributaries could block more than 100 kinds of fish from swimming upstream, causing massive losses to diversity and fish supply. This could also be particularly worrying for the number of communities that rely on fishing for their livelihoods.

In all, researchers identified 877 fish species in the Mekong River Basin, 103 of which would be potentially blocked from making their upstream migrations by hydropower development. In particular four planned dams were found to create the largest fish biomass losses, including the Lower Se San 2 in Cambodia, causing a 9.3% drop in fish biomass basin-wide.

Lead author Guy Ziv from Stanford University pointed out that the disappearance of just 1% of fish in the basin would be akin to losing 10,000 tons of food. He emphasised that these impacts needed to be weighed up against the potential benefits of the hydropower.

For more information see: "Trading-off fish biodiversity, food security, and hydropower in the Mekong River Basin,” by Guy Ziv, Eric Baran, So Nam, Ignacio Rodríguez-Iturbe, and Simon A. Levin
10.1073/pnas.1201423109

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