Genetic variation in body weight and flesh colour of the coho salmon ( Oncorhynchus kisutch) in British Columbia

Abstract

Variation in growth and flesh colour was examined for 6 populations of coho salmon ( Oncorhynchus kisutch) from British Columbia. For each population, 5 males were mated with 10 females in a nested breeding design, and the juveniles reared for 1 year in fresh water and about 18 months in sea water. At the end of freshwater rearing, smolt weight differed significantly among populations, with the mean weight ranging from 22 to 38 g. Instantaneous daily growth rates in fresh water ranged from 1.05 to 1.22% per day among populations. Poor seawater growth rates were observed, with the increase in weight per day ranging from 0.47 to 0.56%. Substantial variation in final body weight was observed among populations, and the heritability of final seawater body weight was 0.6 ± 0.3. The genetic and phenotypic corrlations of freshwater and seawater body weights were 0.38 and 0.10, respectively. Overall survival in the study was low (25.4%), and varied significantly among populations. Heritability of flesh colour was 0.2 ± 0.1, and the genetic correlation between final body weight and flesh colour was about 0.4 ± 0.5. The substantial differences in growth, survival, and flesh colour among coho salmon populations, and strong additive genetic control of growth within populations, indicate that the choice of founding population and subsequent selective breeding practices will greatly influence the production characteristics of domesticated coho salmon strains developed for aquaculture.