GENETIC AND PHENOTYPIC PARAMETERS FOR CORTISOL AND GLUCOSE STRESS-RESPONSE IN ATLANTIC SALMON AND RAINBOW-TROUT

Plasma cortisol and glucose levels were monitored in large numbers of hatchery-reared full- and half-sib families of Atlantic salmon (553 full-sib groups) and rainbow trout (281 full-sib groups) following a standardized confinement stress. The approximately normally distributed frequency of cortisol concentrations exhibited mean values in Atlantic salmon that were similar over the four year-classes examined and more than twice as high as in rainbow trout in two of three year-classes. The post-stress glucose levels were of the same order of magnitude in the two species and stable over year-classes. Heritability estimates (h2) for cortisol and glucose were low in Atlantic salmon (mean across year-classes 0.05 and 0.03); in rainbow trout cortisol levels exhibited heritability estimates of low to medium magnitude (mean 0.27), whereas h2 of glucose was low (mean 0.07).