Genetic variation in survival of Atlantic salmon during the sea-rearing period

Abstract

Data from three year-classes of Atlantic salmon were analysed to estimate the heritability for survival during the sea-rearing period. The overall survival for each year-class during 2 years in the sea was 31.8, 51.1 and 25.5%. Haemorrhagic syndrome (“Hitra disease”) was the main cause of death in all year-classes. Heritabilities for survival calculated on the observed scale varied from 0 to 0.21, based on the sire components of variance. Heritabilities for survival were also calculated for two separate parts of the seawater phase. Correlations between sire least square means for survival and body weight, length and condition factor at slaughter were positive in general, but varied from −0.18 to 0.38. Correlations between sire least square means for survival and % immature fish after 1.5 years in the sea were negative in general, but varied from −0.45 to 0.03.