Pre-slaughter stunning of farmed salmon is the most impactful single welfare intervention available in fish aquaculture — yet remains inconsistently adopted across the global industry.
The welfare case for pre-slaughter stunning of salmon is clear and uncontested among fish welfare scientists. CO2 exposure — the most common method globally — causes aversive gill irritation before insensibility; live chilling is slow and potentially distressing. The distress indicators shown by unstunned fish — escape behaviour, opercular movements, and cortisol spikes — are consistent with a conscious animal experiencing aversive stimuli. Given that effective stunning technology exists, is commercially viable, and produces better fillet quality alongside welfare benefits, the failure to mandate it globally represents one of the most tractable and important welfare improvements in aquaculture.