Wild populations of the iconic Mekong giant catfish will be driven to extinction if hydropower dams planned for the Mekong River go ahead, says a new report by WWF. Current scientific information suggests the Mekong giant catfish migrate from the Tonle Sap Lake in Cambodia up the Mekong River to spawn in northern Thailand and Laos. Any dam built on the lower Mekong River mainstream will block this migration route.