The slaughter of farmed fish involves tens of billions of animals annually with widely varying welfare standards. Developing and adopting humane slaughter methods for fish is one of the most impactful welfare interventions in the food system.
Fish slaughter welfare represents arguably the largest single welfare improvement opportunity in the global food system by number of individual animals affected. Current methods used for most farmed fish cause significant suffering before death: live chilling in ice slurry causes a prolonged period of consciousness and distress as body temperature drops; carbon dioxide exposure causes irritation and distress before loss of consciousness; simply removing fish from water causes hypoxic distress lasting many minutes. The evidence that fish experience these as aversive states is substantial: they show avoidance, stress hormones, and behavioral indicators of distress during these procedures. Humane slaughter for fish is technically achievable: percussive stunning renders fish immediately insensible before killing, and electrical stunning systems for aquaculture have been developed for salmon and trout. The barriers to adoption are primarily economic — investing in humane slaughter infrastructure — and attitudinal — the perception that fish welfare at slaughter does not matter. Retailer welfare standards, consumer demand for certified products, and regulatory requirements are all levers that can drive adoption of more humane methods at scale.