GENETIC CORRELATIONS BETWEEN SURVIVAL OF ATLANTIC SALMON IN CHALLENGEAND FIELD-TESTS

Four sub-samples of 171 full-sib groups of Atlantic salmon presmolts ( the offspring of 96 sires and 171 darns) were tested for survival afte r challenge with the pathogenic bacteria Areomonas salmonicida, Vibrio salmonicida, Vibrio anguillarum and the viral disease Infectious Salm on Anaemia (ISA). Another sub-sample of 123 of the full-sib groups was tested as postsmolts at a marine test-site (field test) where infecti on with A. salmonicida prevailed causing high mortality during a two-m onth summer period. A full-sib group mean MINQUE model was used to est imate the variance and covariance components for survival in each test environment. Estimated heritabilities on the underlying liability sca le for survival in the challenge test with A. salmonicida was 0.53 (at 50% survival) and in the field test 0.38 (at 65% survival). The genet ic correlation between survival in the two tests was 0.95. Thus, the r esults give good prospects for genetic improvement of resistance to fu runculosis when survival data from challenge tests of presmolts are us ed as the selection criterion. The results also indicate a positive ge netic correlation between resistance to each of the bacterial diseases , but a weak negative genetic correlation between resistance to the vi ral disease ISA. and resistance to each of the bacterial diseases. (C) 1997 Elsevier Science B.V.