Salmon welfare assessment is moving beyond absence of disease to positive indicators of good welfare. This shift requires understanding what thriving looks like for this species.
The welfare science of farmed salmon is undergoing a significant conceptual shift, moving from a focus solely on preventing negative states such as disease, injury, and stress toward also assessing and promoting positive states. This is both scientifically important and practically challenging: positive welfare in fish is harder to define and measure than in mammals, and requires understanding what salmon find rewarding, stimulating, and comfortable. Research is identifying promising indicators including playful swimming behaviour, voluntary approach to novel objects, and tight schooling in calm conditions. These indicators are beginning to be incorporated into on-farm welfare assessment tools that can be used by farmers and auditors. The goal is to characterise farms not merely as places where fish survive, but as environments where fish can flourish within the constraints of commercial production.