Pre-slaughter welfare in salmon aquaculture involves crowding, pumping, and stunning processes that cause significant stress, and the adoption of effective stunning methods is one of the most impactful welfare improvements available.
Pre-slaughter salmon welfare is one of the most tractable welfare improvements in aquaculture — the technologies for effective stunning exist, their welfare benefits are clear, and the business case through flesh quality improvement aligns commercial and welfare interests. Yet the majority of farmed salmon globally are still killed using CO2 immersion, which causes aversive behavior and prolonged distress before loss of consciousness. The transition to in-water electrical stunning or percussive stunning for individual fish represents the most impactful single welfare improvement available in the salmon farming sector. Norwegian regulatory requirements for effective stunning have demonstrated that industry-wide adoption is achievable when required by regulation. Consumer demand for certified products with humane slaughter standards and retailer sourcing requirements are the primary pressure points for accelerating adoption in other producing countries.