Responses to two generations of index selection in Atlantic salmon ( Salmo salar)

Abstract

Linear indices were used to select broodstock for two generations of a Canadian Atlantic salmon strain. In 1988, a select line was formed on the basis of an index to increase fry length, percent S1 smolts and market and mature length. In 1992, the broodstock for the following generation of select families was chosen on the basis of an index to increase percent S1 smolts, percent non-grilse, market length and bacterial kidney disease resistance. There was an unselected control line for both generations. Progeny of selected parents compared to those of control parents for both generations showed positive direct and indirect responses to selection for various freshwater and seawater growth and development traits. The most significant response was found for harvest size, where a gain of 0.83 standard deviations was achieved after two generations. This represents on average an actual gain of 0.88 kg per fish. The mean harvest weight for select fish was 4.39 kg vs. 3.51 kg for control fish.