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

Mid – Columbia Study Area

Miles of stream inhabited by O Miles of stream inhabited by O. mykiss in subbasins of the Mid Columbia Steelhead ESU Life history type Basin Mixed Rainbow Steelhead Totals Deschutes 121 1,665 396 2,182 John Day 17 3,196 3,213 Klickitat 80 185 264 Umatilla 736 417 1,154 Walla 107 638 745 Yakima 302 500 457 1,260 423 3,105 5,289 8,817

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.

% Wild Steelhead on Spawning Grounds

Adult summer steelhead collected at the fish trap on Birch Creek (Umatilla River)   Wild Htchry % Htchry Birch Ck % Htchry 3-Mi Dam 1995-96 143 6 4% 43% 1996-97 109 5% 38% 1997-98 85 1 1% 59% 1998-99 73 0% 51% 1. mark/recapture study in 1995-96 that approximately 30% of the wild steelhead counted at Three-Mile Dam were accounted for in Birch Creek that year. 2. clear evidence that assumptions employed Chilcote (2001) about mixing of hatchery and wild fish when he estimated the probability of extinction for steelhead in the Umatilla Basin are false. Chilcote (2001) found there was a high probability of extinction in the Umatilla Basin

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

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

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

Correlation Matrix of Naturally Produced Steelhead Abundance Trends

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

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

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