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The Problem
Supplementation is the release of artificially propagated fish to maintain or increase natural production (through natural spawning by hatchery) while maintaining the long-term fitness of the target population. Supplementation has been identified as a major tool for the restoration of salmonids in the Columbia River system as well as other streams throughout the Pacific Northwest, yet data suggest that its biological and economic efficacies may be far less than generally expected. This study evaluates costs and benefits for alternative sources of broodstock for supplementation, and tests for domestication in hatchery programs. The study tests for genetic differences in the migration, growth, and survival of hatchery and wild steelhead (Oncorhynchus mykiss) and of hatchery and wild spring chinook salmon (O. tshawytscha) in both natural streams and hatcheries. Steelhead will be from Idaho's Clearwater River, and spring chinook salmon from Oregon's Warm Springs River. Results from this study should be extremely valuable to those planning or managing supplementation or its evaluation because rigorous quantitative genetic comparisons of hatchery and wild salmon have been available only for steelhead, and the general applicability of these data to steelhead as well as other species of salmon has been seriously challenged. Objectives The 5-year research goals of the Fisheries and Aquatic Resources Program addressed are to: understand relationships between and among aquatic species habitats; provide science for restoring and maintaining declining species and their required habitat; and investigate aquatic species diversity. Objectives for steelhead are:
Objectives for spring chinook salmon are:
Methodology The methods involve crossing adult fish to produce genetically marked progeny of hatchery x hatchery, hatchery x wild, and wild x wild parentage. The different groups of progeny are incubated in identical conditions in the hatchery until button-up when the groups are mixed together. Mixed populations are divided; some are released into natural streams, others are reared in the hatchery. The progeny are sampled before or during their downstream migration or as returning adults to determine relative growth and survival of the treatment groups. The relative performances will be used to infer effects on stock productivity from using offspring of wild fish in the hatchery and hatchery fish in streams and to design evaluations. Highlights and Key Findings 4/19/02 - During the past 12 months we have been trapping downstream migrants and sampling juvenile
4/30/01 - Completed trapping and monitoring of experimental juvenile steelhead in Idaho, but continue to monitor and evaluate returns of experimental adult steelhead. Evaluation of reproductive success for returning adult steelhead was abandoned because only seven adults returned to the study stream in 2000. Approximately 200 returning adult spring chinook salmon from the 1996 year-class were sampled from the fisheries and the hatchery and were genetically assayed to determine relative survival and growth. Final results must await the return of age-5 adults in 2001; however, preliminary results indicate
3/28/00 - Experimental groups of steelhead are rearing in two natural streams, and at sea. Experimental groups of spring chinook salmon are rearing in a stream and in Warm Springs National Fish Hatchery. Preliminary results indicate genetic differences such that progeny of WxW matings survive better in streams than do progeny of HxH matings. HxH steelhead survive and grow better in the hatchery than do WxW steelhead. 2/2/00 - Downstream recoveries of PIT-tagged steelhead smolts after release from Clearwater Hatchery indicated substantially reduced survival of progeny from wild fish, compared to progeny from hatchery fish, and intense selection for "hatchery-type" fish. Recovery rate was positively related to smolt size, and the HxH fish grew faster in the hatchery than did WxW fish, but recovery of HxH fish also was greater than recovery of WxW fish of the same size. Survival of HxH chinook salmon from swim-up to smolt in
Where Are We Headed In 2003 DNA and parentage analyses, data analysis, and report preparation will continue during FY 2003, and should be complete for all but Objective II.2 by 2004. Project Contact Reg Reisenbichler Email: reg_reisenbichler@usgs.gov Publications |
