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Impact of Hatchery Strays on Steelhead Recruitment in Mid-Columbia Subbasins

This study by Steve Cramer & Brent Lister examines hatchery-wild interbreeding and its effect on steelhead recruitment in Mid-Columbia subbasins. Findings highlight the differences in hatchery fish percentages among natural spawners and the implications for steelhead populations. The study focuses on the Umatilla and Deschutes rivers, noting the impact of hatchery spawners on key production areas. Analysis of steelhead abundance trends and correlations provide valuable insights for fisheries management.

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Impact of Hatchery Strays on Steelhead Recruitment in Mid-Columbia Subbasins

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  1. Effects of Hatchery Strays On Recruitment of Steelhead in Mid Columbia Subbasins Steve Cramer & Brent Lister Funded byYakima Joint Board S.P. Cramer & Associates, Inc. Fisheries Consultants www.spcramer.com

  2. Mid – Columbia Study Area

  3. Miles of stream inhabited by O. mykiss in subbasins of the Mid Columbia Steelhead ESU

  4. Hatchery & Wild Interbreeding • Only Umatilla and Deschutes show >10% hatchery fish among natural spawners • % Hatchery spawners is much lower in key production areas than at passage monitoring stations.

  5. % Wild Steelhead on Spawning Grounds

  6. Adult summer steelhead collected at the fish trap on Birch Creek (Umatilla River)

  7. Average Wild Steelhead Recruits per Parent Spawner, 1978-97 broods

  8. Average Wild Steelhead Recruits per Parent Spawner, 1985-97 broods

  9. Warm Springs River as Control • Major tributary of Deschutes River • USFWS operates a weir where nearly all fish entering the river are trapped • Only unmarked steelhead are released above the weir

  10. Correlation Matrix of Naturally Produced Steelhead Abundance Trends

  11. *Index includes all of John Day, Yakima and Warm Springs

  12. *Index includes all of John Day, Yakima and Warm Springs

  13. Conclusions • Population productivity per wild spawner was not measurably affected by hatchery spawners • Trends in abundance of Mid-Columbia steelhead are driven by factors common to all populations • Hatchery strays do not fully mix with wild fish and produce fewer recruits • Hatchery strays should be treated as a separate population when estimating stock recruitment parameters

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