Prespawning stress in farmed Atlantic salmonSalmo salar: maternal cortisol exposure and hyperthermia during embryonic development affect offspring survival, growth and incidence of malformations

In the current study, mature female Atlantic salmon Salmo salar were given intraperitoneal cortisol implants with the purpose of elucidating potentially detrimental effects on offspring survival, growth, morphological development and also the ability of prenatally stressed offspring to cope with an environmental stressor, typified by a period of mild hyperthermia. Augmented levels of maternal cortisol inflicted a range of progeny somatic parameters, as reflected in increased mortality, reduced fork length and mass, diminished yolk‐sac volume, decelerated yolk‐sac utilization and, to some extent, enhanced prevalence of morphological malformations. The most pronounced consequences on offspring performance were demonstrated in specimens exposed to both enhanced prenatal cortisol and a subsequent episode of hyperthermia. This accentuates the importance of knowledge on how the maternal endocrinological state during gametogenesis may impinge on offspring characters in farmed Atlantic salmon, and further substantiates the necessity of incorporating maternal effects when evaluating rearing conditions and animal welfare in commercial aquaculture.