Complete diallel cross between five strains of Atlantic salmon

The effect of cross-breeding on survival, growth and maturity when crossing five Norwegian strains of Atlantic salmon has been investigated. A diallel cross including purebred strains and their reciprocal crosses was used. Additive, maternal and heterosis effects were studied. Total heterosis was partitioned into average, general and specific heterosis. Growth of maturing and immature males and females was also considered.Significant total heterosis was found for survival of fry, survival of fish after marking (marked at one year of age), body weight of fingerlings and body weight of adults. However, average heterosis was low for all traits. For survival of eyed-eggs, alevins and fingerlings, dressing percentage and maturity, total heterosis was not significantly different from zero.It is concluded that cross-breeding Norwegian strains of Atlantic salmon seems to have little practical significance in a future breeding program.