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First Generation Results Published in:

• First Generation Results Published in:
• Knudsen, C. M., S. L. Schroder, C. A. Busack, M. V. Johnston, T. N. Pearsons, W. J. Bosch, and
• D. E. Fast. 2006.
• Comparison of life-history traits between first-generation hatchery and wild Upper Yakima River spring Chinook salmon.
• Transactions of the American Fisheries Society 135:1130–1144.

First Phase Objective: Compare first generation hatchery and wild origin fish returning from broodyears 1997 to 2000.

Phase 1 Conclusions

• Wild fish were larger at age (grew faster) in all years, differing by as much a 1 SD from hatchery fish
• The differences in body size were significant in all comparisons accept BY2000 age 4’s
• Differences observed in age-3 fish had to occur sometime over the ~16 months after release

Phase 1 Conclusions - cont’d

• Age Composition – increasing proportion of hatchery age 3 returns.
• Sex Ratios – increasing proportion of hatchery male returns.
• Passage timing at RAMF - Hatchery and wild was significantly different in some years, but the differences were relatively small with no trend.
• Spawn timing at CESRF - Hatchery fish consistently spawned earlier by 5.1 days on average.

First Phase Objective: Compare first generation hatchery and wild origin fish returning from broodyears 1997 to 2000. Second Phase Objective: Compare second generation Hatchery- and Natural-origin fish returning from broodyears 2001 to 2004.

Yakima River Basin

Age Composition

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Size-at-Age (reflecting growth rates)

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POHP (+ 1 sd) Age 4 Females and Males 2006

High and Low Growth Treatments

High and Low Growth Juvenile Body Weight

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ANOVA: High vs Low POHP

Spawn Timing At CESRF

Spawn Timing At CESRF

Conclusions

• Hatchery fish continue to return at smaller size-at-age than Natural origin fish
• Increased proportions of age 3 jacks continues
• Age 4 fish from all Yakima River populations have significantly declines in size since 2001
• 2006 was the first year we observed significant sexual dimorphism (females>males)
• Spawn timing of hatchery fish at CESRF was once again earlier than natural origin fish

Acknowledgements

• Yakama Nation Roza Adult Monitoring Facility Crew
• Cle Elum Supplementation and Research Facility Crew
• Bonneville Power Administration for providing funding

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