The evidence base for humane fish stunning and slaughter methods across different aquaculture species.
Fish slaughter welfare represents a high-impact, achievable improvement that is limited primarily by knowledge, equipment investment, and industry motivation. The evidence that common methods including ice slurry and CO2 cause prolonged consciousness during the killing process — with associated pain and distress — is well established, and the alternative methods (percussive and electrical stunning) are technically straightforward and commercially available. The welfare case for transitioning to humane stunning is clear, and it is buttressed by a quality case: fish killed without stress show better flesh quality, improved color, and longer shelf life. Consumer demand for certified humane seafood and regulatory requirements are the most effective levers for accelerating industry transition. The scale of fish slaughter — hundreds of millions of individuals in aquaculture alone — makes even incremental improvement in stunning reliability significant at the population level.