Pre-slaughter welfare for farmed salmon involves ensuring fish are rendered unconscious before killing. The adequacy of current stunning methods is an active area of research and regulatory attention.
Pre-slaughter welfare for fish has lagged dramatically behind standards for terrestrial farm animals. While stunning is legally required before slaughter of pigs, cattle, and poultry in the EU and UK, fish are routinely slaughtered by methods that would be considered unacceptable for mammals. The scientific evidence supporting fish pain experience has strengthened to the point where this difference in treatment is difficult to justify ethically. Effective electrical stunning systems exist and are commercially viable. The welfare case for mandatory effective stunning of farmed salmon and other fish species before slaughter is well-established; what is lacking is regulatory requirement and industry will.