The Spatial Ecology and Entrainment Vulnerability of Adult Bull Trout in a Large Hydropower Reservoir

To date, the majority of research on fish entrainment in hydropower reservoirs has focused on downstream migrating smolts with comparatively little known about the entrainment vulnerability of adult fish. Given that vulnerability to entrainment is likely to fluctuate with seasonal changes in adult behaviour (e.g., spawning migrations), the first step to quantifying entrainment vulnerability is to examine spatial ecology over multiple seasons. Here we describe an ongoing study to examine the spatial ecology of adult bull trout (Salvelinus confluentus) in Kinbasket Reservoir, British Columbia. Kinbasket Reservoir is 210 kilometres long and was created after the completion of the Mica Dam, a large earth fill structure designed to impound the upper Columbia River to control flooding and generate hydroelectricity. In the spring of 2010 we deployed 43 acoustic telemetry receivers and tagged 187 bull trout to detect their presence throughout the system including a number of key spawning tributaries. Transmitters were also equipped with depth sensors to provide additional information on seasonal depth distribution. Data were downloaded after monitoring fish movements for a year including under ice conditions. The results from this study provide the first year round assessment of bull trout spatial ecology in a large lentic system. This study will also lay the ground work for a sophisticated entrainment vulnerability assessment that will examine high-resolution movement in conjunction with hydrodynamics at the dam/forebay interface.