Genetic correlation for body weight of Atlantic salmon grilse between fish in sea ranching and land-based farming

Abstract

A research programme in salmon ranching in Iceland was started in 1987. The primary aim was to study the genetic variation in the frequency of return to the site of smolt release. The purpose of this investigation was to estimate the genetic correlation between the body weight of fish returning from sea ranching and the body weight of their full- and half-sibs reared in land-based farms. Fish from two year-classes were used, and progenies of 220 full- and 76 half-sib families were included. Significant effects of sex and age at sexual maturation on body weight were observed. For sea ranching, males were larger than females, and mature males and females were larger than immature fish at the land-based farms. The mean body weight of fish returning from sea ranching was more than two times larger than their sibs reared at the land-based farms. Heritability estimates for the body weight of grilse from salmon ranching for 1989 and 1991 year-classes were 0.20 ± 0.10 and 0.23 ± 0.12, respectively. The heritability estimates for body weight of grilse at land-based farms for 1989 and 1991 year-classes were 0.31 ± 0.17 and 0.27 ± 0.10, respectively. The genetic correlation between body weight of fish returning from sea ranching and land-based farming was 0.42 ± 0.28 for the 1989 year-class and 0.27 ± 0.34 for the 1991 year-class.