New hatchery management strategies in the Columbia River Basin focus on conservation of naturally spawning populations as an equal priority to providing fish for harvest—a difficult halance to achieve. The Hatchery Scientific Review Group (HSRG) assessed 178 hatchery programs and 351 salmonid populations to determine how to achieve managers’ goals for conservation and sustainable fisheries. Modeling determined the best strategy, using an approach based on best available science, goal identification, scientific defensibility, and adaptive management to refocus from an aquaculture paradigm to a renewable natural resource paradigm. We concluded that hatcheries and natural populations must be managed with the same biological principles. HSRG solutions improved the conservation status of many populations (25% for steelhead trout, more than 70% for Chinook and coho salmons) while also providing increased harvest. Natural‐origin steelhead trout and coho salmon spawners increased by 6,000 to 10,000; Chinook salmon increased by more than 35,000 compared to current numbers. Hatchery juvenile production decreased slightly, and in most cases production shifted from populations of concern. Overall harvest potential increased from 717,000 to 818,000 fish by focusing on selective fishing and by reheating some in‐river harvest closer to where the fish originate. With habitat improvements, often the number of natural‐origin fish nearly doubled.
A genetic investigation of anadromous trout populations in the Puget Sound area revealed numerous juvenile individuals from two streams with electrophoretic phenotypes consistent with those expected for hybrid descendents of steelhead trout (Salmo gairdneri) and coastal cutthroat trout (S. clarki clarki). The likelihood of hybridization was evaluated with a hybrid index measuring the relative probability that the combined genotype for a particular fish at several diagnostic loci could have arisen by random mating within each of the two Salmo species. The distribution of hybrid index scores among fish from the two creeks clearly demonstrated the genetic distinctness of the two species and the intermediate genotypic composition of the unknown fish. We concluded that these electrophoretically intermediate fish were natural steelhead–cutthroat hybrids based on their restricted occurrence at specific sample sites in only 2 of 23 streams surveyed, the linear distributions of juveniles from the two parental species within each stream, and the distribution of hybrid index values for a hatchery population of known mixed ancestry. Further, from estimates of gametic disequilibria and the absence of a consistent excess of heterozygotes we suggest that backcrossing may have occurred. The existence of these natural hybrids raises many questions concerning the biological bases for maintaining species integrities in regions of sympatry and indicates the need to fully understand the biological consequences of present and future management practices.
To determine the genetic origin of individual sturgeon that are morphologically intermediate to pallid (Scaphirhynchus albus) and shovelnose (Scaphirhynchus platorhynchus) sturgeon, we combined previously published mitochondrial DNA (mtDNA) and microsatellite data with additional microsatellite data. Two sympatric populations of pallid and shovelnose sturgeon from the upper Missouri River and a sympatric population containing pallid, shovelnose, and putative pallid-shovelnose hybrids from the Atchafalaya River were analyzed using an index of hybridization and a principle components analysis of individual relatedness scores. The addition of new microsatellite data improved our ability to genetically differentiate individual pallid and shovelnose sturgeon collected in both areas. Our methods distinguished morphologically intermediate Atchafalaya River sturgeon, which appear to be genetically intermediate between pallid and shovelnose sturgeon. The results support a hybrid origin for morphologically intermediate individuals, although it is unclear whether they are all first-generation hybrids or if some are the result of subsequent backcrossing with the more common shovelnose sturgeon.
Hatcheries support nearly all major fisheries for Pacific salmon (Oncorhynchus spp.) and steel‐head (anadromous O. mykiss) in the Pacific Northwest. However, hatcheries have been a major source of controversy for over 30 years. The Hatchery Scientific Review Group (HSRG) was tasked by Congress to identify solutions to well‐known problems so hatcheries could better meet their goals of supporting sustainable fisheries and assisting with the conservation of natural populations. We reviewed over 100 facilities and 200 programs and identified three principles of hatchery reform: (1) goals for each program must be explicitly stated in terms of desired benefits and purposes; (2) programs must be scientifically defensible; and (3) hatchery programs must respond adaptively to new information. We also identified several emerging issues critical to the success of hatcheries. We concluded that hatcheries must operate in new modes with increased scientific oversight and that they cannot meet their goals without healthy habitats and self‐sustaining, naturally‐spawning populations.
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