The construction of the massive Xayaburi dam in Laos could force the Mekong giant catfish, one of the world’s largest species of freshwater fish, into extinction, according to a new study commissioned by the World Wildlife Fund.
Like many of Southeast Asia’s largest indigenous species, giant catfish were once abundant in the region, but the “megafish” is now an elusive creature and the new study sheds some light on its outlook if the controversial dam project gets the green light.
“The Mekong giant catfish symbolizes the ecological integrity of the Mekong River because the species is so vulnerable to fishing pressure and changes in the river environment,” Lifeng Li, director of WWF’s global freshwater program, said in a statement accompanying the report.
According to the study, there could be as few as 200 adult Mekong giant catfish left in the Lower Mekong. The study says that the 1260-MW Xayaburi dam—which Cambodia and Vietnam are against—may ultimately apply too much pressure on the threatened species for it to survive.
“A fish the size of a Mekong giant catfish will simply not be able to swim across a large barrier like [the Xayaburi] dam to reach its spawning grounds upstream,” the study’s author, professor Zeb Hogan from the University of Nevada, said in the statement.
Finish firm Poyry, which is advising construction of the Xayaburi dam, has argued that fish passages, or ladders, can be constructed to enable fish to get past the dam’s turbines. However, such techniques would not help fish the size of the Mekong giant catfish to migrate.
According to a paper published in 2000 in scientific journal BioScience, such measures are not appropriate for the Mekong River.
“Fish ladders, which may serve as a means to mitigate the impacts of dams on migratory fishes, are unlikely to be successful in the Mekong because most species in the river do not jump,” the paper authored by David Dudgeon says.
Despite the fact that a 2011 agreement was reached to delay construction on Xayaburi dam in order to assess the long-term social and environmental costs, Laos is reportedly pushing ahead with the project without the consensus of neighboring Cambodia and Vietnam—as was stipulated by the 1995 Mekong Agreement.
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