Downstream effects of hydroelectric dam operation on thermal habitat use by Brook Trout ( Salvelinus fontinalis ) and Slimy Sculpin ( Cottus cognatus )

• Published in: Ecology of Freshwater Fish
• Main Authors: Kelly, Brianne, Smokorowski, Karen E., Power, Michael
• Other Authors: Fisheries and Oceans Canada, Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Ecology; Aquatic Science; Ecology, Evolution, Behavior and Systematics; Cottus cognatus; Slimy sculpin
• Online Access: http://dx.doi.org/10.1111/eff.12299; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Feff.12299; https://onlinelibrary.wiley.com/doi/pdf/10.1111/eff.12299

Abstract Hydroelectric dams can alter downstream water temperatures, impacting thermal habitat available for fishes. Decreases in river water temperatures resulting from hydroelectric dam operations may be beneficial to coldwater species and could potentially offset warming resulting from climatic trends. We used two coldwater fish species, Slimy Sculpin ( Cottus cognatus ) and Brook Trout ( Salvelinus fontinalis ) to assess the impact of a cool water draw below a 15 MW hydroelectric dam on fish thermal habitat use relative to a nearby naturally flowing river. Cooler water temperatures below the dam corresponded with significantly cooler mean growth season temperature use for Slimy Sculpin, but not Brook Trout, relative to the natural river. As well, mean growing season temperature use by Slimy Sculpin was significantly cooler relative to Brook Trout in both rivers, and significantly different amongst studied sites in the regulated river. Fish condition was significantly correlated with temperature use for Slimy Sculpin in the naturally flowing river only. Our results indicate that manipulating river water temperatures through hydroelectric dam operations to benefit multiple fish species will be difficult given the complexity of riverine thermal habitat and species‐specific differences in thermal preferences and behaviour.