Variation in growth rate and age at first maturation in rainbow trout

Abstract

The present report is an account of the main results of a series of experiments on selective breeding of rainbow trout. The experiments started in 1972, but were discontinued in 1979 because IPN virus was detected in the material. Growth rate and age at first sexual maturity were the main factors studied. Full sib and half sib correlations as well as parent/offspring correlations were applied. The results were not always conclusive because the different year classes gave somewhat different results. However, sib correlations indicated control by additive genetic factors for at least part of the variation in growth rate. This was also confirmed by the parent/offspring results. Both additive and non-additive genetic factors were indicated as controlling the variation in age at first maturation. No effect of the age of first maturation of the individual parent fish could be found among the offspring, but there was a clear effect of the mean maturation age of the parent sib group on the maturation age of the offspring group.