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Subyearling Chinook Survival and Environmental Factors at Lower Granite to McNary Dam, 1998-2007

This study examines the survival and travel time of PIT-tagged hatchery subyearling Chinook passing Lower Granite Dam, and evaluates the effect of environmental variables such as flow, spill, temperature, and water transit time on their survival. The study also compares the timing of subyearling fall Chinook in 2006 with historic timing, and analyzes environmental conditions and their impact on survival.

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Subyearling Chinook Survival and Environmental Factors at Lower Granite to McNary Dam, 1998-2007

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  1. Hatchery Subyearling Survival Lower Granite to McNary Dam 1998 to 2007(preliminary results) Fish Passage Center

  2. Overview • PIT-tagged Hatchery Subyearling Chinook passing LGR dam during two-week blocks from May 20 to July 15 each year • Estimate Survival and Travel Time for blocks • Assign average environmental variables during passage such as Flow, Spill, Temperature and Water Transit Time • Show bivariate plots of Reach Survival and environmental variables.

  3. Lower Granite to McNary Dam Reach

  4. Timing of Subyearling fall Chinook at LGR Dam in 2006 compared to Historic Timing

  5. Survival for Hatchery Subyearling Chinook LGR to McN 1998 to 2006 with 95% CI’s

  6. Comparison of Environmental conditions at LGS 1998 to 2007 Flows in 2007 were low from late May through the end of July; similar to 2001 Spill proportion was high in 2007 but volumes were low Temperatures were warm in 2007 similar to 2005 and 2006

  7. Hatchery Subyearling Chinook Survival vs Avg Spill Pct LGS, LMN, IHR, McN

  8. Water Transit Time • WTT--Avg Time for Water Particle to Transit Reservoir • Q -- discharge at dam

  9. Converting Flows to Water Transit Time

  10. Hatchery Subyearling Chinook Survival vs sum WTT LGS, LMN, IHR, McN

  11. Hatchery Subyearling Chinook Survival vs Avg Temp LGS, LMN, IHR, McN

  12. Hatchery Subyearling Chinook Survival vs WTT and Spill Proportion

  13. Conclusions • For actively migrating subyearling Chinook, increased spill and decreased water transit time (higher flows) appear to improve survival, while higher temperatures decrease survival

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