In 2023, all but one Swedish restocking farm rearing Baltic salmon and sea trout fry experienced massive mortality caused by lipoid liver disease (LLD). The struck farms used the same feed, and this was suspected to be the cause of the outbreak. We performed two parallel feed trials in three salmon populations as well as fatty acid and antioxidant analyses of feed and fish to investigate the causal relationship between the fee...

Anadromous brown trout ( Salmo trutta ) in the northeastern Atlantic Ocean, and coastal cutthroat trout ( Oncorhynchus clarkii clarkii ) in the northeastern Pacific Ocean, are analogs in many ways. Both species display similar patterns of complex life histories and behavioral flexibility, are iteroparous and facultatively anadromous and occupy nearshore coastal marine habitats where numerous populations often mix. These charac...

Evolution of phenotypic plasticity requires genotype–environment interaction. The discovery of two large‐effect loci in the vgll3 and six6 genomic regions associated with the number of years the Atlantic salmon spend feeding at sea before maturation (sea age), provides a unique opportunity to study evolutionary potential of phenotypic plasticity. Using data on 1246 Atlantic salmon caught in the River Surna in Norway, we show t...

This paper reviews the life history of brown trout and factors influencing decisions to migrate. Decisions that maximize fitness appear dependent on size at age. In partly anadromous populations, individuals that attain maturity at the parr stage typically become freshwater resident. For individual fish, the life history is not genetically fixed and can be modified by the previous growth history and energetic state in early li...