Supplementing natural fish populations with artificially propagated (hatchery) fish is a common practice. In evaluating supplementation, it is important to assess the relative fitness of both hatchery-produced and naturally produced fish when they spawn together in the wild and to evaluate how the absolute fitness of the natural population changes after many generations of supplementation. We evaluated the relative fitness of naturally produced and hatchery-produced coho salmon (Oncorhynchus kisutch) in Minter Creek, Washington, USA. We also evaluated longterm changes in natural smolt production in this stream after several decades of intensive hatchery supplementation. Total smolt production was estimated to be 14 660 and 19 415 in 2002 and 2003, respectively, compared with the average value of 28 425 from 1940 to 1955. We found no significant difference in relative fitness between hatchery and natural fish, probably because the natural population consists largely of fish produced from the hatchery a generation or two previously. There has been a long-term trend for adults to return to the stream earlier in the spawning season. We estimated standardized selection differentials on run timing, with results indicating stabilizing selection with an optimum run timing later than the mean contemporary run timing but earlier than the historical mean run timing. Résumé :On ajoute couramment des poissons élevés artificiellement en pisciculture aux populations naturelles de poissons. En évaluant ces ajouts, il est important de mesurer la fitness relative tant des poissons de pisciculture que des poissons élevés en nature lorsqu'ils fraient ensemble dans le milieu et de déterminer comment la fitness absolue de la population naturelle change après plusieurs générations de ces ajouts. Nous évaluons la fitness relative de saumons coho (Oncorhynchus kisutch) élevés en pisciculture et en nature à Minter Creek, Washington, É.-U. Nous déterminons aussi les changements à long terme de la production naturelle de saumoneaux dans ce cours d'eau après plusieurs dé-cennies d'ajouts importants de poissons de pisciculture. Nous estimons la production totale de saumoneaux à respectivement 14 660 et 19 415 en 2002 et 2003, alors que le nombre moyen était de 28 425 de 1940 à 1955. Nous ne trouvons aucune différence significative de fitness relative entre les poissons de pisciculture et les poissons sauvages, probablement parce que la population naturelle est composée en grande partie de poissons produits en pisciculture il y a une ou deux générations. Il y a chez les poissons une tendance à long terme à retourner au cours d'eau plus tôt dans la saison de fraie. Nous estimons les différentiels standardisés de sélection dans le calendrier de la montaison qui indiquent l'existence d'une sélection stabilisante; la montaison optimale se situe plus tard que la montaison actuelle, mais plus tôt que la période moyenne de montaison dans le passé.[Traduit par la Rédaction] Ford et al. 2355

We used genetic parentage analysis of 6200 potential parents and 5497 juvenile offspring to evaluate the relative reproductive success of hatchery and natural steelhead (Onchorhynchus mykiss) when spawning in the wild between 2008 and 2011 in the Wenatchee River, Washington. Hatchery fish originating from two prior generation hatchery parents had <20% of the reproductive success of natural origin spawners. In contrast, hatchery females originating from a cross between two natural origin parents of the prior generation had equivalent or better reproductive success than natural origin females. Males originating from such a cross had reproductive success of 26–93% that of natural males. The reproductive success of hatchery females and males from crosses consisting of one natural origin fish and one hatchery origin fish was 24–54% that of natural fish. The strong influence of hatchery broodstock origin on reproductive success confirms similar results from a previous study of a different population of the same species and suggests a genetic basis for the low reproductive success of hatchery steelhead, although environmental factors cannot be entirely ruled out. In addition to broodstock origin, fish size, return time, age, and spawning location were significant predictors of reproductive success. Our results indicate that incorporating natural fish into hatchery broodstock is clearly beneficial for improving subsequent natural spawning success, even in a population that has a decades-long history of hatchery releases, as is the case in the Wenatchee River.

-For at least 15 years, multiple Pacific Rim Laboratories have cooperated to standardise the collection of Pacific salmon genetic data. For species such as Chinook salmon and chum salmon, allozyme electrophoretic data sets now include hundreds of populations sampled over multiple years throughout the north Pacific. More recently, microsatellite DNA markers have emerged as a new cornerstone of Pacific salmon genetic research. The allozyme experience provides at least two important lessons regarding shared, standardised databases. First, interlaboratory standardisation is sufficiently costly and time consuming that little progress is typically made in the absence of specific fishery management and conservation needs; thus immediate needs will direct future standardisation. Secondly, justified or not, there are significant concerns regarding intellectual propriety and other perceived privileges associated with unpublished genetic data that are shared among laboratories. This article describes challenges to genetic standardisation relative to new research goals, along with specific suggestions for meeting those challenges.