Research Document - 2016/039
Upstream passage and entrainment of fish at hydropower dams: lessons learned from NSERC’s HydroNet 2010-2015
By Lee F.G. Gutowsky, Philip M. Harrison, Ana Silva, Eduardo G. Martins, Michael Power, David Z. Zhu, Steven J. Cooke
River ecosystems require connectivity to sustain productive habitats whereas hydro -electric generation requires river flows be stored, diverted and passed through turbines. Clearly these two requirements are at odds. However, advancements in technology, engineering and biology have collectively helped toward reconciling these issues. HydroNet, a National Science and Engineering Research Council of Canada Strategic Network Grant and Collaborative Research and Development Grant, was designed in part to investigate the key variables related to hydropower that affect the productive capacity of fish habitats around hydropower facilities. This included investigating the behavioural and ecological correlates of upstream fish passage (as occurs at fishways designed to afford bidirectional movement of fish past barriers including dams) and adult fish entrainment (the process by which fish are displaced from reservoirs by water diversion structures at dams). Here we summarize and synthesize results from a number of studies generated under the HydroNet grant. From this synthesis we generate a list of lessons learned to help direct future studies on fish passage and entrainment in Canada and abroad. Research was performed in the Vianney-Legendre fishway on the Richelieu River in Quebec and the Mica Dam on Kinbasket Reservoir in British Columbia, Canada. From the beginning both research problems were tackled through collaborations with engineers and biologists who generated results under the assumption that informed assessments require a complete understanding of both the physical and biological components related to upstream passage and entrainment. Using a number of techniques including radio telemetry and Computational Fluid Dynamics modeling (CFD), fishway passage efficiency was found to be strongly dependent on species-specific physiology and the hydraulic conditions present throughout the structure. In addition, there was also evidence that some fish species were spawning downstream of the dam such that fish passage may not always be needed. Future fishway research would benefit from collaborative relationships between engineers and biologists to help design fishways and improve passage efficiency. In addition, there is need to consider under what conditions fish passage is necessary and what passage efficiency targets are necessary for a given system. CFD modeling and acoustic telemetry showed that entrainment was dependent on species’ spatial ecology and behaviour. Fish were entrained during winter when the system was isothermal and dam operations would have minimal effect on thermal regimes. Similar to our recommendations on fishway research, studies on entrainment should include collaborative relationships, utilize new technologies, and consider how hydropower operations and design of water diversion structures influence entrainment. This research synthesis should provide a considerable contribution toward understanding the physical and behavioural correlates of fishway passage and entrainment at dams. We hope that some of the lessons learned will help to direct future research to better align the objectives of energy development with the hydraulic and ecological conditions necessary to maintain the productive capacity of fish habitats around hydropower facilities.
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