Conservation behaviour in action: using fish behaviour to understand and mitigate the impacts of hydropower development

The impacts that hydropower facilities have on non-anadromous downstream migrants and other resident freshwater fish are increasingly being recognized by environmental managers. The overall goal for my thesis was to apply conservation behaviour and risk analysis approaches to inform decision making for avoiding/mitigating common hydropower-related hazards faced by freshwater fish. Specifically, the thesis considers the risks of injury and mortality from entrainment and exposure to supersaturated total dissolved gasses (TDG). Many studies have quantified entrainment-related mortality and injury, but these studies generated site-specific data. To address this knowledge gap, I conducted a systematic review to quantify the risk associated with common hydropower infrastructure. My results revealed an increased overall injury and mortality risk resulting from entrainment relative to control fish. An increased risk was also revealed for several infrastructure types and fish taxa. To examine the re-entrainment risk of a freshwater resident fish, I tracked the movements of salvaged Kokanee salmon in the forebay area of a large hydropower facility. Telemetry data revealed minimal re-entrainment risk for salvaged Kokanee at the facility. Several studies have examined spatial-temporal movements of diadromous fish relative to TDG levels, but few have examined resident fish species. To examine the TDG exposure risk of resident fish, TDG was modeled in an impounded hydro-affected river system, and I tracked Rainbow Trout and Mountain Whitefish movement and depth use. Telemetry data revealed patterns in MW reach and depth residency that corresponded to spawning, foraging, and refuge behaviour whereas RT exhibited high site fidelity in one area of the system. The risk assessment revealed that Rainbow Trout had a higher TDG risk exposure relative to Mountain Whitefish, and that risk was highest in both species at locations near one of the hydropower facilities. The results presented in this thesis are novel in that they provide some of the first empirical data to quantify the risk of common hazards associated with hydropower facilities and will, therefore, be useful from a hydropower management perspective. Moreover, this thesis provides an example of how to incorporate fundamental behavioural research into hydropower management regimes and frameworks through the use of risk analysis.