How farmed salmon are killed at slaughter has profound welfare implications. Research comparing methods shows significant welfare differences that consumer choice and regulation can address.
Salmon slaughter welfare is a domain where scientific understanding has advanced rapidly but industry practice lags significantly. The evidence that CO2 stunning is aversive - fish actively avoid CO2-treated water even when the alternative is confinement - means current widespread use of this method causes preventable suffering in hundreds of millions of fish annually. Conscious gill-cutting causes distress that can be observed behaviorally and measured physiologically for several minutes. The adoption of effective stunning methods (percussion, correct electrical protocols) represents one of the highest-impact welfare improvements available in salmon aquaculture given the scale of slaughter. Consumer preference for certified products can accelerate this change.