Isolation of salmonid microsatellite loci and their application to the population genetics of Canadian east coast stocks of Atlantic salmon

Genetic variation at four microsatellite loci, two isolated from Atlantic salmon and two from rainbow trout, was assayed in five populations of Alantic salmon from Nova Scotia, Canada and in samples from Norway and Ireland. Up to 38 allelles per locus and heterozygosities of 0.9 were observed at some loci. Genetic distances, calculated over the four loci for all population samples show a clear grouping of populations according to geographic location. These loci show potential as genetic markers in Atlantic salmon due to the range of polymorphisms observed among individual loci and to the ease and speed of sample assay. Highly variable loci will be of use in the 'genetic ragging' of cultured fish and in the assessment of levels of gene introgression from cultured to wild stocks. The clear differences in both allele frequencies and alleles observed between continents will be of value in the assessment of the relative sizes of the contributions of Canadian and North European salmon to the mixed fishery off Greenland.