Pre-slaughter handling of farmed Atlantic salmon causes significant welfare harm. Understanding the welfare implications of crowding, air exposure, and stunning methods informs industry improvement.
Pre-slaughter salmon welfare is an area where significant improvement is technically achievable but not yet universally practiced. Crowding stress before harvest causes elevated cortisol and reduced insensibility thresholds. CO2 immersion, while widely used, causes a period of avoidance behavior and respiratory distress before insensibility - indicating a prolonged aversive experience. Water-based electrical stunning provides rapid insensibility and is the preferred welfare method when properly calibrated. The challenge is applying it consistently across industrial-scale salmon processing. Norway's mandatory stunning requirement provides a regulatory model others could adopt.