Farmed Salmon Pre-Slaughter Welfare

Welfare science for Atlantic salmon in the period immediately before slaughter, covering fasting protocols, crowding stress, stunning methods, and the evidence base for humane salmon slaughter practices.

Key Facts

Pre-slaughter fasting of 24-96 hours is used to empty gut content, affecting welfare through hunger and metabolic changes
Percussive stunning using automated systems can be effective for salmon but requires maintenance for reliable efficacy
Electrical water bath stunning is used in some operations but concerns exist about incomplete stunning at commercial scales
CO2 narcosis — bubbling carbon dioxide through water — causes aversive distress in fish before loss of consciousness
Spiking — manual brain destruction — provides reliable humane kill but is labor-intensive at commercial scales
The RSPCA specifies electrical stunning followed by spiking as the recommended method for farmed salmon
Post-stun checks for sensibility are important to verify that stunning was effective before processing proceeds

Welfare Considerations

Pre-slaughter welfare for salmon encompasses several distinct phases each with significant welfare implications. Fasting duration represents a welfare tradeoff between industry quality requirements and fish welfare — extended fasting causes measurable hunger-related stress and behavioral changes. Crowding for harvest causes acute stress. The stunning method ultimately determines whether fish experience pain and fear during killing. CO2 narcosis causes aversive distress before unconsciousness, making it a welfare-inferior method regardless of its operational convenience. Best practice — electrical stunning to immediate insensibility followed by spiking — is technically feasible at commercial scale and removes the welfare concern of conscious death entirely. Market demand for higher welfare salmon and certification requirements are the primary drivers of improved pre-slaughter practice.

What You Can Do

Choose RSPCA Assured certified salmon as the best available assurance of humane pre-slaughter welfare standards
Ask salmon brands and retailers what slaughter method their suppliers use and whether CO2 is avoided
Support campaign for banning CO2 narcosis as a primary salmon slaughter method and requiring electrical stunning
Learn about salmon slaughter welfare to make more informed purchasing decisions at seafood counters
Advocate for mandatory humane slaughter requirements for farmed fish to be included in aquaculture regulations