Past, present, and future of genetic improvement in salmon aquaculture

The fanning of Atlantic salmon has become an important industry in several countries, and breeding programmes have been implemented to improve genetic performance and adaptation to farm environments. Founder stocks used in the Norwegian salmon breeding programme have originated solely from Norwegian rivers and no extrinsic genes have been introduced. The majority (more than 90%) of the additive genetic variation in Norwegian populations of Atlantic salmon has been found within, and not between, river strains. The Norwegian breeding programme comprises four subpopulations. In the event of reduced additive genetic variability due to random drift in the closed breeding populations, crosses between the sub-populations could be made to re-establish the variability. Selection in itself is not expected to reduce the additive genetic variability as long as inbreeding is avoided. To date, seven different traits (body weight at slaughter, age of sexual maturation, survival in challenge tests with furunculosis and ISA, flesh colour, total fat content, and amount of fat tissues) have been included in the breeding goal. The selection response obtained is about 10% per generation for each of these traits. In the future, more traits are likely to be included. The results of and prospects for selective breeding and the use of modern DNA technology to improve genetic performance in aquatic species are discussed. (C) 1997 International Council for the Exploration of the Sea.