Rainbow trout are farmed in large numbers across Europe. Slaughter methods vary widely in their welfare impact, with significant differences in time to unconsciousness.
Trout have a complex nervous system and behavioural indicators of pain. Slaughter without prior stunning causes prolonged suffering as fish are placed in ice or suffocate. The welfare case for mandatory stunning is strong and economically feasible. Consumer demand for humane slaughter drives industry adoption where regulation is absent.