Development of a selection index to improve market value of cultured Atlantic salmon (Salmo salar)

Genetic variation in susceptibility of Atlantic salmon to the sea louse Caligus elongatus Nordmann, 1832

Differences in susceptibility of distinct full-sibling families of Atlantic salmon, Salmo salar, to infection with the sea louse Caligus elongatus were investigated. Infection intensity with mobile stages of sea lice was monitored on 419 individual salmon from 73 full-sibling families held in a single sea pen and exposed to similar numbers of infectious larvae originating from nearby fish. The average intensity of infection calculated from the family groups ranged from 5 to 25, with 70 families having an average intensity of 10 or more preadult or adult sea lice. The overall average intensity was 15.30 and the prevalence was 100%. The calculated genetic heritability (h2) was 0.22, which indicates that this variability in susceptibility to infection may be heritable. This level of heritability also suggests that selection for improved resistance to sea lice is feasible.

Genetics of size and growth rate through sexual maturity in freshwater-reared coho salmon (Oncorhynchus kisutch)

Genetic parameters of size through sexual maturity have been relatively unexplored for Pacific salmon. In this study, individually tagged coho salmon were raised in freshwater, and the heritabilities of size and growth rate were estimated at several intervals between 13 and 24 months of age (spawning). Heritability estimates for size were moderate to high from 13 to 19 months of age, ranging from 0.36 to 0.50, and lower from 21 months to spawning at 24 months, ranging from 0.17 to 0.32. Heritabilities of specific growth rates estimated over 3-month intervals were moderate from 16 to 21 months of age, ranging from 0.21 to 0.34. Genetic and phenotypic correlations between sizes measured at different ages were moderate to high, ranging from about 0.7 to 1.0. Correlations between growth rate and size indicated that the larger fish were the fastest growing between 16 and 19 months of age and were slower growing between 19 and 21 months of age.