Turbine Survival of Silver Eels: What Do We Know and How Can We Improve It?

Due to relatively high mortality rates, turbine entrainment of silver eels is a major issue that is being addressed by hydro project owners and resource agencies throughout the world.  Eels have unique morphological, physiological, and behavioral characteristics that differentiate them from other species with respect to turbine mortality and the effects of various injury mechanisms (e.g., strike, pressure, shear). Consequently, existing turbine survival field data and established strike probability and mortality models used to estimate turbine survival of more typical teleost species generally are not applicable to silver eels.  Available field and laboratory data from turbine survival studies conducted with eels indicate they have higher survival rates for their size than would be expected for other species.  We are currently conducting an assessment of these data and alternative predictive methods for estimating eel turbine survival to provide a better understanding of how turbine design and operation affect eel injury and mortality rates.  Based on this assessment, potential design and operational modifications will be identified and eel-specific theoretical approaches for predicting strike probability and mortality will be developed.