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  • 1
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Electrophoretic studies of proteins remain a primary source of insight into genetic diversity in many species including the Atlantic salmon Salmo salar, one of the most culturally and economically important fish species of the North Atlantic region. Since 1966, 〉350 scientific papers on protein variation have been published encompassing 25 000+ salmon from over 400 locations in 〉200 river systems across the species’ distribution. Variation has been detected at 30% of the 110 protein loci screened, though most studies examine 〈40. The method has been applied largely to the investigation of population structure and differentiation, but work has also led to the systematic revision of the genus Salmo and remains the primary source of insight into hybridization in the wild with brown trout Salmo trutta. Spatial patterns of differentiation show temporal stability, both within and among river systems, and strongly support structuring of the species into river and tributary specific populations and the designation of European and North American populations as distinct sub-species. They also show widespread regional differentiation within both continents, beyond the marked subcontinental differences between Baltic Sea and Atlantic Ocean populations in Europe. Most of the differentiation probably reflects gene flow and founder events associated with colonization following the retreat of the glaciers from much of the species’ modern range. However, variation at MEP-2* shows strong correlations with environmental temperature, both within and among rivers, and associations with phenotypic performance. This suggests selection is acting on the locus and provides compelling evidence for the local adaptation of populations. Protein studies have led to more population centred management of the species and have been exploited in the discrimination of regional stocks in mixed stock analysis in high seas fisheries, particularly in the Baltic Sea, and as markers for the assessment of stocking success. They have also advanced insight into how the genetic character of populations can be changed in cultivation and the potential impact of salmon aquaculture and stocking on wild populations. The method has been largely superseded by DNA based analyses, but the results remain highly relevant to Atlantic salmon management and conservation and are an irreplaceable data set for studying genetic stability of populations over time.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 67 (2005), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Genetic evidence for the selective exploitation by anglers of early running fish was examined in four Iberian Atlantic salmon populations using protein and mtDNA markers. The populations studied had been exploited exclusively by anglers since 1949 during a fixed fishing season that ran approximately from March to July. Genetic variation at six protein loci was small and was accounted for by the MEP-2* and MDH-3,4* polymorphisms, which generally remained stable over time and were in Castle–Hardy–Weinberg equilibrium during the fishing season. Early running fish that had spent multiple winters at sea (MSW) generally had higher frequencies of the common MEP-2*(100) allele than did late running, one sea winter (1SW) grilse that were significantly smaller and tended to escape the fishery. Spawners differed from angler caught fish in their mtDNA frequencies and consistently had a lower sea-age and a smaller body size. Spawners also smolted at an older age and displayed lower frequencies of the MEP-2*(100) allele in three of the four populations studied. These results suggest that in these rivers anglers selectively exploit a distinct component of the population and inadvertently cause a differential mortality of genetic types that is likely to be detrimental to population viability.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Journal of fish biology 65 (2004), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Compared to wild populations, cultured Atlantic salmon often sustain higher mortality rates and lower adult return rates when stocked as juveniles into natural streams. The ultimate causes for such differences in fitness, however, are not clear. Here we tested if relaxed levels of natural selection and improved survival in the hatchery environment could account for the observed degree of maladaptation among stocked fish. To do this, we assessed the degree of phenotypic mismatch between wild and cultured fish in three populations over five consecutive years. Significant differences were found in several phenotypic traits that are likely to have fitness implications. Thus, if the objective is to mimic wild individuals for restoration purposes, current hatchery practices aimed at maximising juvenile survival and enhancing growth may need to be revised.
    Type of Medium: Electronic Resource
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