Distribution of genetic variation in brown trout, Salmo trutta L., in Scotland

Abstract. A total of 1680 brown trout, Salmo trutta L., from 63 different localities in Scotland were sampled and examined for 34 loci. Thirteen loci were polymorphic in one or more populations. The mean observed heterozygosity for wild populations ranged from 0.0 to 8-9% (x=4.5%) in the same range as previous studies on this species. Within drainage studies and gene diversity analysis confirms that a large proportion (33%) of total gene diversity was distributed between populations. The Ldh-5(100) allele was common in Scottish populations and its distribution would fit the hypothesis that this allele was indicative of an ancestral trout population in Scotland before the invasion of trout characterized by the Ldh-5(90) allele. The results have important implications for the management of the brown trout genetic resource.