Rainbow trout slaughter methods vary considerably in humaneness, with percussive stunning and spiking providing the most welfare-positive outcomes.
Rainbow trout experiencing slaughter without prior stunning undergo prolonged distress during dying. Asphyxiation in air causes a gradual, distressing death over many minutes. CO2 causes hyperventilation and distress responses before unconsciousness. Percussive stunning renders fish immediately unconscious when correctly applied, eliminating pre-death suffering. Correct blow position and sufficient force are critical for welfare; poorly applied percussion causes injury without unconsciousness. Electrical stunning achieves reliable unconsciousness rapidly when properly calibrated. Welfare certification increasingly requires stunning as a condition of third-party auditing.