Pre-slaughter stunning of farmed fish is the most significant single welfare intervention available in aquaculture; adoption is growing but remains inconsistent across species and regions.
Fish stunning at slaughter represents the highest-leverage single intervention available in aquaculture welfare. Without stunning, fish subjected to asphyxiation, gill cutting, or live gutting may remain conscious and in pain for extended periods. The scale — tens to hundreds of billions of individuals annually — means that even marginal improvements in stunning rates aggregate to enormous welfare gains. Percussive stunning (a physical blow to the skull) and electrical stunning produce rapid, reliable insensibility in salmonids and are increasingly used in larger processing facilities. Smaller species present greater challenges: trout, sea bass, and sea bream can be stunned electrically; shrimp and other crustaceans require different approaches. Regulatory mandates from Norway have shown that industry compliance with stunning requirements is achievable without prohibitive cost.