Evaluating the Effects of Dam-Altered Flow Regimes on the Swimming Activity, Behaviour and Survival of Adult Sockeye Salmon (Oncorhynchus nerka)

Anadromous adult Pacific salmon (Oncorhynchus spp.) encounter hydraulically challenging areas of difficult passage (high-gradient reaches, dams) during their reproductive migration. While the direct effects of dam operations on wild fishes are well documented (e.g., delayed movements, excessive energy-use), comparatively little is known as to the delayed, post dam passage effects of these barriers. Using acoustic accelerometer transmitters and model selection analyses, Chapter 2 assessed how managed flow releases from a dam influenced the swimming activity, behaviour and passage success of sockeye salmon (O. nerka). Building on this framework, Chapter 3 explored the potential for high-flow-induced burst swimming below the dam to predict the mortality of sockeye salmon. Findings from this research provide novel insight into the mechanisms that contribute to the delayed mortality of migratory fishes. Future studies investigating the indirect effects of dams will improve our ability to provide effective passage solutions to watersheds that are impacted by hydropower development.