Mortality assessment for adult European eels (Anguilla Anguilla) during turbine passage using CFD modelling

Collisions, shear events and barotrauma are severe causes of fish mortality in a hydroelectric turbine. Fish-adapted turbine management and environmentally enhanced turbines can be mitigation measures. To use those measures efficiently, knowledge about turbine mortality is needed. In this study, a combination of CFD modelling, fish passage modelling and mortality assessment was used to evaluate mortality for different operating points of a Kaplan bulb turbine for adult European eels (anguilla anguilla). Calculated mortality due to collisions varied from 22% to 37%, due to shear events from 7% to 14% and due to barotrauma from 0% to 18%. The operating points with discharges between 70% and 85% of maximum discharge yielded the lowest mortality values. This supports the idea that a fish-adapted turbine management is possible that gives preference to operating points that are less hazardous to fish than others. Based on this approach it is possible to distinguish the locations within a turbine where hazardous hydraulic conditions occur making it a valuable tool in the design process and the biological performance evaluation of a turbine-management plan without needing to implement it first. Furthermore, no animal experiments are necessary for this approach. (c) 2019 Elsevier Ltd. All rights reserved.