PAST, PRESENT, AND FUTURE OF GENETIC-IMPROVEMENT IN SALMON AQUACULTURE

The fanning of Atlantic salmon has become an important industry in sev eral countries, and breeding programmes have been implemented to impro ve genetic performance and adaptation to farm environments. Founder st ocks used in the Norwegian salmon breeding programme have originated s olely from Norwegian rivers and no extrinsic genes have been introduce d. The majority (more than 90%) of the additive genetic variation in N orwegian populations of Atlantic salmon has been found within, and not between, river strains. The Norwegian breeding programme comprises fo ur subpopulations. In the event of reduced additive genetic variabilit y due to random drift in the closed breeding populations, crosses betw een the sub-populations could be made to re-establish the variability. Selection in itself is not expected to reduce the additive genetic va riability as long as inbreeding is avoided. To date, seven different t raits (body weight at slaughter, age of sexual maturation, survival in challenge tests with furunculosis and ISA, flesh colour, total fat co ntent, and amount of fat tissues) have been included in the breeding g oal. The selection response obtained is about 10% per generation for e ach of these traits. In the future, more traits are likely to be inclu ded. The results of and prospects for selective breeding and the use o f modern DNA technology to improve genetic performance in aquatic spec ies are discussed. (C) 1997 International Council for the Exploration of the Sea.