A planned dam on the Mekong River in Laos promises to disrupt the reproductive cycle of the giant catfish, one of the world’s largest freshwater fish, but experts disagree on how best to help it.
The Xayaburi hydroelectric dam will stand in the way of the Pangasianodon gigas, thought to migrate hundreds of kilometres from the Tonle Sap Lake in Cambodia to spawn near Chiang Khong in northern Thailand, after passing through Xayaburi province in northern Laos.
Cambodia and Vietnam, downstream of the project, have expressed concern over potential impact on fish migration and sediment flows.
Both countries have urged that the $3.5-billion dam — the first on the Lower Mekong — be postponed until the impact has been thoroughly evaluated.
Studies are under way, but Laos and its Thai partners are proceeding with construction, scheduled for completion in 2019.
The design includes a fish ladder: a series of watery shelves alongside the dam that allow migrating species to make their way upstream and past the obstacle.
But experts fear the giant catfish, which can grow to 3 metres and 300 kilograms, will be unable to use it.