Journal of Fish Biology (2011) 79, 575–586 doi:10.1111/j.1095-8649.2011.03036.x, available online at wileyonlinelibrary.com Stressed mothers – troubled offspring: a study of behavioural maternal effects in farmed Salmo salar M. S. Eriksen*†, G. Færevik*, S. Kittilsen*, M. I. McCormick‡, B. Damsg ˚ ard§, V. A. Braithwaite‖¶, B. O. Braastad* and M. Bakken* *Department of Animal and Aquacultural Sciences, Norwegian University of Life Sciences, P. O. Box 5003, NO-1432 ˚ As, Norway, ‡ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia, §Nofima Marin, Muninbakken 9-13, P. O. Box 6122, NO-9291 Tromsø, Norway, ‖School of Forest Resources and Department of Biology, Penn State University, PA 16802, U.S.A. and ¶Department of Biology, Bergen University, P. O. Box 7800, NO-5020 Bergen, Norway (Received 22 June 2010, Accepted 12 May 2011) Mature female Atlantic salmon Salmo salar were given intraperitoneal cortisol implants 1 week prior to stripping to examine the influence of simulated maternal stress on offspring boldness and social dominance. Behavioural tests originally designed to investigate stress responsiveness and coping styles in salmonids (i.e. feeding in isolation, dominance tests and acute confinement) were carried out on the offspring 1·5 years after hatching. In the feeding test, there were no differences between the two treatment groups in total feeding score or number of pellets eaten, but offspring from the cortisol-implanted females made more unsuccessful feeding attempts than offspring from control females. In dominance tests, there was no difference between controls and cortisol-treated fish regarding propensity to become socially dominant. A higher proportion of individuals with bite marks, however, was observed in the cortisol group when compared to controls. Cortisol- treated offspring that gained dominant rank in the dominance tests performed more aggressive acts after stable dominance–subordinate relationships were established compared to control winners. During acute confinement stress, offspring from cortisol-implanted females showed a reduction in the proportion of time they were moving compared to the controls. These results indicate that the maternal endocrine state at spawning affects several aspects of progeny behaviour potentially related to subsequent success and survival in farmed S. salar.  2011 The Authors Journal of Fish Biology  2011 The Fisheries Society of the British Isles Key words: aggression; boldness; cortisol; dominance; stress; welfare. INTRODUCTION Many studies on animals have established that a wide variety of stressors experi- enced by breeding females can exert profound impacts on progeny characteristics (Huizink et al., 2004). In mammals and birds, prenatally stressed offspring typically suffer from increased mortality, lowered birth mass, congenital abnormalities and †Author to whom correspondence should be addressed. Tel.: +47 6496 5169; email: marit-skog.eriksen@ umb.no 575  2011 The Authors Journal of Fish Biology  2011 The Fisheries Society of the British Isles