The period immediately before salmon slaughter — crowding, pumping, and crowding into wellboats — causes acute, intense stress that represents a critical welfare failure point.
The pre-slaughter phase is among the highest-suffering periods in farmed salmon's lives. The convergence of extreme crowding, physical handling, and transport creates a cascade of welfare harms: cortisol surges, physical injuries, gill damage from reduced oxygen, and panic responses. Fish at extreme density display frantic swimming, surface-breaking, and injury from collisions. The duration of this high-stress phase — potentially lasting 12–24 hours from initial crowding to slaughter — means accumulated suffering is substantial. Innovations such as dry-well harvest systems, in-pen stunning, and gentler pumping reduce harm significantly, but remain non-mandatory and are not universally adopted.