PNNL

Abstract

The development of hydropower throughout the world is set to address the global increase in energy needs. However, the impact to the riverine ecology systems, including native fauna and flora, is not well understood. The Mekong River Basin is one of the world’s largest waterways and is the target of hydropower expansion. It is also one of the most biodiverse rivers; serving as home to many species which undergo large-scale migrations that are blocked or hindered by the development of hydroelectric dams. One source of injury and mortality for downstream migrating fishes is passage through the turbine environment. During passage, fishes native to the Mekong River Basin may be exposed to a number of physical stressors (e.g., shear forces, rapid decompression, blade strike, turbulence). The goal of the current study was to understand the susceptibility of two key species for the Mekong River, blue gourami (Trichopodus trichopterus) and iridescent shark (Pangasianodon hypophthalmus) to shear forces. Fishes were exposed to an underwater jet with velocities up to 21.3 m/s (equating to strain rates of up to 1,185 s-1) and were assessed for behavioral effects, injuries, and mortality. Overall, it was determined that both species were susceptible to shear forces and the effects were more pronounced at higher strain rates, and gouramis were more susceptible than sharks. The results of this study can be used in the Mekong River Basin to inform the design and operation of hydroturbines to minimize the impact for native species.