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Lower Columbia River Rainbow Trout Spawning Assessment and Egg Mortality Study

Department: Environmental
  • Client: BC Hydro
  • Location: Lower Columbia River (LCR) downstream of the Hugh L. Keenleyside Dam to the Canada-U.S. border, and the Lower Kootenay River (LKR) downstream of the Brilliant Dam.
  • Timeline: 2019 - 2024
  • Purpose:

    The primary goal was to assess the effects of flow management on Rainbow Trout egg mortality and population abundance in the Lower Columbia and Lower Kootenay Rivers, focusing on evaluating the impact of alternating the Rainbow Trout Spawning Protection Flows (RTSPF).
  • Services:
    • Monitoring of redd and spawner counts via aerial, boat, and drone surveys.
    • Environmental data collection, including temperature and water levels.
    • Statistical modeling and analysis of Rainbow Trout spawning and recruitment trends.
    • Egg and alevin mortality surveys and incubation assessments.
    • Integration of drone-based monitoring for habitat and spawning data.
  • Outcome:

    The project assessed the effectiveness of RTSPF, with key findings on the rate of redd dewatering and its limited impact on subsequent recruitment. It highlighted a ten-fold increase in spawner abundance since 1999 and the potential impact of density-dependent factors on egg mortality. The study's outcomes aim to guide future water use planning and management strategies.