End-of-life welfare for farmed trout varies significantly. Effective stunning and rapid killing are welfare requirements that remain inconsistently implemented.
Trout killed by CO2 or ice slurry without prior effective stunning experience a prolonged process of dying that, given evidence for fish sentience, likely involves suffering. Electrical stunning that renders fish immediately insensible before killing represents the welfare-optimal method currently available. Regulatory requirements for effective stunning before trout slaughter would prevent enormous numbers of welfare-negative deaths annually.