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

a measurable impact on the population dynamics of C. magister.1 Schweitzer and Feldmann (2010) proposed elevating the Cancer subgenus, metacarcinus, outlined by Nations (1975) to the generic level re-classifying the Dungeness crab as Metacarcinus magister based solely on the shape of carapace teeth. Due to a lack of molecular evidence (Harrison and Crespi 1999) to support Nations' subdivisions, the lead author elected to maintain the use of Cancer magister.

Saving valuable time in genetics research has been thoroughly addressed by the biotechnical industry in the form of ever‐faster and safer DNA isolation and genotyping systems, such as solvent‐free robotic DNA isolation stations, fast polymerase chain reaction (PCR) machines, and semiautomated genetic analyzers. As a result, the time bottleneck has shifted to the tissue‐processing phase of many projects. We developed and tested a fish tissue collection method that reduces this bottleneck by replacing liquid preservative with chromatography paper, thus providing important time‐saving advantages and greater convenience while removing hazardous material constraints from tissue handling. The results show that genomic DNA isolated from caudal‐fin tissue samples collected on chromatography paper is similar in mean total yield, gel appearance, and PCR performance to DNA from tissues collected with ethanol in tubes. This collection method also reduces tissue‐processing time to a small fraction of the time traditionally required.

Captive breeding is a commonly used strategy for species conservation. One risk of captive breeding is domestication selection--selection for traits that are advantageous in captivity but deleterious in the wild. Domestication selection is of particular concern for species that are bred in captivity for many generations and that have a high potential to interbreed with wild populations. Domestication is understood conceptually at a broad level, but relatively little is known about how natural selection differs empirically between wild and captive environments. We used genetic parentage analysis to measure natural selection on time of migration, weight, and morphology for a coho salmon (Oncorhynchus kisutch) population that was subdivided into captive and natural components. Our goal was to determine whether natural selection acting on the traits we measured differed significantly between the captive and natural environments. For males, larger individuals were favored in both the captive and natural environments in all years of the study, indicating that selection on these traits in captivity was similar to that in the wild. For females, selection on weight was significantly stronger in the natural environment than in the captive environment in 1 year and similar in the 2 environments in 2 other years. In both environments, there was evidence of selection for later time of return for both males and females. Selection on measured traits other than weight and run timing was relatively weak. Our results are a concrete example of how estimates of natural selection during captivity can be used to evaluate this common risk of captive breeding programs.