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Title: Population genetics of salmon in Wales
Author: O'Connell, M. D.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1993
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Atlantic salmon (Salmo salar L.) were examined using protein electrophoresis and mitochondrial DNA (mtDNA). A total of 614 individuals were examined using allozymes at 19-21 loci. The sites were distributed over five catchments throughout Wales. Significant differences in allele frequencies are observed both within and between rivers. The allele frequencies appear stable over the time period investigated. Multiple enzyme genotypes from 170 individuals were collected at 28 sites from six rivers in Wales. AvaII, DdeI, HaeIII, HinfI and MboI are variable, although DdeI was only assayed in a restricted number of individuals. Sequence divergence appears low in salmon mtDNA. However, small but significant differences are again observed between and within rivers. Preliminary results suggest that mtDNA genotype frequencies remain stable over time. When the data sets are compared, allozymes appear at least as useful as mtDNA in identifying significant differentiation between populations of Welsh salmon. The mtDNA results suggest that future surveys of Atlantic salmon need to sample at least 25 individuals per site, to identify all the genotypes present. Although hatchery samples do not show reduced levels of variability, when compared to natural populations, both data sets reveal the Dee to have the lowest level of within catchment differentiation. The low level of population structuring may be due to the intensive stocking carried out on the river over the last decade. The strict regulation of flow within the catchment may also be responsible for the low value. The monomorphic nature of MDH-3* in Welsh salmon means that variants introduced into the region could be identified. Another potential genetic tag is the MboI B genotype, which is restricted to salmon populations within South-west England and south Wales.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available