Program in Ecological Physiology
Capability/Technical Service - Evaluation of hatchery/wild fish interactions.
Definition. Many hatchery programs can pose genetic and/or ecological risks to wild stocks due to adverse interaction for food, habitat, and/or mates. Decisions regarding conservation priorities and conservation actions can be difficult to make in the absence of knowledge of the interactions between hatchery fish and their wild counterparts. This underscores the need for comprehensive studies which examine this issue from a variety of view points, for example, juveniles interactions for prey items and habitat, outmigration timing and freshwater juvenile survival and adult return rates.
Development of a Native Broodstock for Use in Restoration and Recovery
Many hatchery programs for steelhead pose genetic or ecological risks to natural populations because those programs release or outplant fish from non-native stocks. As a result, the USFWS and the NOAA Fisheries have recommended a policy that discourages the use of non-native hatchery stocks and encourages development of native broodstocks. To meet Service goals and a NMFS BiOp, Abernathy Fish Technology Center (AFTC) staff are establishing a native broodstock of natural spawning steelhead to recover wild steelhead populations. The study is evaluating the effects of integrated hatchery practices on wild ESA populations for application throughout the Columbia River basin. The objective is to develop methods to produce hatchery fish that do not involve the use of ESA-listed adults that in turn will be used to develop a native broodstock. Results should produce a means to produce self-sustaining stocks of steelhead that have applicability for use in salmon recoveries throughout the Pacific Region. We initiated our steelhead broodstock program by captively rearing wild juveniles to sexual maturity. 500 naturally spawned juvenile steelhead from the locally adapted population were collected over 3 years (1999-2001). 20,000 juveniles have been released from AFTC yearly since 2003. We successfully produced and released steelhead smolts and evaluated their behavior, morphology, physiology, and reproductive success relative to wild fish. Our data suggest that wild smolt production has not been effected by hatchery releases. Hatchery and wild steelhead differ morphologically and physiologically. Genetic diversity among the broodstock and progeny has been maintained. Hatchery returns have reproduced naturally. Hatchery and wild fish produced equivalent numbers of offspring.
Partners NOAA Fisheries and the Washington Department of Fish and Wildlife
Hill M. S., G. B. Zydlewski, and W. L. Gale. 2006. Comparisons between hatchery and wild steelhead trout Oncorhynchus mykiss smolts: Physiology and habitat use. Canadian Journal of. Fisheries and Aquatic Sciences 63:1627-1638.
Kennedy B. M., W. L. Gale, and K. G. Ostrand. 2007. The relationship between smolt development and migration timing to avian predation risk of steelhead (Oncorhynchus mykiss) in a large estuary. Canadian Journal of Fisheries and Aquatic Sciences 64:1506-1516.
Incidence and Effects of Hatchery Steelhead Piscivory Upon Juvenile Salmonids
As the roles of NFHs shift from fisheries supplementation to that of conservation and restoration it becomes paramount to assess the effects that hatchery production has upon threatened and endangered native populations. Hatchery juvenile steelhead may directly predate upon native fish compromising conservation efforts. The initial incidence of fry predation by hatchery fish is assumed to be low; however, it is unknown whether individuals failing to emigrate utilize native fry as a food source and effect native populations. We assessed fry predation rates by hatchery steelhead during emigration following their release and among those that failed to migrate. Emigrating steelhead were captured on Abernathy Creek in using a rotary screw trap and resident steelhead were captured by electrofishing and angling. Stomach contents were collected and identified. Our results suggest hatchery fish have less impact upon native salmonid fry as compared to naturally produced juvenile steelhead. Piscivory appears to more relate to native fry emergence and subsequent emigration timing as opposed to hatchery production. Nevertheless, we advocate that hatchery releases consider salmonid communities and their stream specific life histories.
Partner: Bonneville Power Administration