Decades of genetic selection in Atlantic salmon farming have created fish that grow faster but may have reduced fitness and welfare in some areas compared to wild salmon.
Genetic selection for production traits creates welfare trade-offs analogous to those in poultry breeding. Rapid growth in salmon is associated with cardiac pathologies including heart and skeletal muscle inflammation (HSMI) that cause suffering and mortality. Some high-growth genetic lines show increased aggression that creates welfare challenges in group-housed sea cages. Genetic programs that incorporate welfare traits including stress resistance, disease resilience, and cardiovascular health alongside production metrics represent a more welfare-conscious approach. Genomic selection tools now enable multi-trait programs that can advance welfare traits without sacrificing production efficiency.