Downstream Passage of Adult European Eel with a Hybrid Fish Guidance System at a Large Hydroelectric Installation in Europe

The lack of available technologies in Europe to exclude downstream migrating silver eels from hydroelectric turbine intakes has resulted in the need for collection and transport of these fish around hydropower installations.  As an alternative, we propose a novel downstream guidance system that combines: (1) an electrical guidance system (EGS) and (2) a flow velocity enhancement system (FVES) with (3) a natural stream-like bypass channel.  The combined EGS and FVES would be deployed upstream of the intake for a hydropower headrace canal and regulating weir.  The guidance system would direct downstream-migrating silver eels to the bypass channel around the regulating weir.  Eel guidance is hypothesized to result from their repulsion from the low-level electric field deployed upstream of the headrace canal intake followed by directional guidance by the FVES-induced flow into the new bypass.  This concept has been developed with facilities on a particular European river in mind, but should be adaptable to other sites.  Eels should benefit from less handling stress than with collection and transport, while hydropower companies should benefit from an installation having low labor costs and more freedom to generate on the demand cycle.