Pre-slaughter handling is a critical welfare period for farmed salmon. The hours before death involve crowding, transport, and stunning procedures that determine suffering levels for billions of fish.
The scientific evidence that fish are sentient and experience suffering is now well-established, making pre-slaughter welfare a serious concern for the billions of farmed salmon killed annually. Pre-slaughter crowding causes acute physiological stress responses comparable to those in warm-blooded vertebrates. Stunning methods that render fish insensible quickly and effectively dramatically reduce the duration and intensity of pre-slaughter suffering. The transition from carbon dioxide stunning, which causes prolonged distress, to percussion or electrical stunning methods is one of the highest-impact welfare improvements available in aquaculture. Producer adoption of effective stunning methods is increasing but remains far from universal.