Heritabilities, dominance variation, common environmental effects and genotype by environment interactions for weight and length in chinook salmon

Genetic and environmental parameters were estimated for weight and length of chinook salmon at the end of the freshwater period and after 9 months of saltwater rearing at three British Columbia salmon farms. The data set consisted of 7549 offspring from three natural spawning strains. Within each strain, 16 sires and 32 dams were used to produce 48 full sib families using a mating design that created genetic ties between families. Families were replicated across two rearing sites. Variance components were estimated both within and across strain using a univariate animal model that included the additive and dominance genetic effects and the common environmental effects of family tank within site as random components. The across-strain analyses resulted in good summaries of the within-strain estimates for saltwater traits but were somewhat low for freshwater traits. Heritabilities, dominance ratios, and intraclass correlations of family tank were 0.24, 0.26 and 0.21, respectively, for freshwater weight and 0.34, 0.08 and 0.08, respectively, for saltwater weight. The results were similar for length. Ignoring dominance and family tank in the analyses resulted in inflated estimates of heritability. No genotype by environmental interaction was found at the strain level. However, the within-site analyses of freshwater traits resulted in reranking of parents. In general, freshwater performance of a family was not a good predictor of saltwater growth.