Atlantic salmon is the most studied farmed fish species for welfare, with a substantial evidence base informing certification standards and management practices.
Atlantic salmon welfare science has advanced substantially over the past two decades, providing a strong evidence base for industry standards. Pain evidence meets the criteria used for vertebrate pain recognition. Stress responses to handling, crowding, and transport are well-characterized. Operational welfare indicators validated for on-farm use include external lesion scoring, eye damage, and behavioral assessment. Cognitive bias testing demonstrates that salmon in better welfare conditions make more optimistic responses to ambiguous stimuli. The evidence base supports the conclusion that salmon are sentient fish whose welfare should be actively managed rather than incidentally considered. Ongoing research into salmon affective states, pain management, and welfare-positive production systems continues to advance the field.