The crowding of salmon into increasingly small spaces before harvest creates acute welfare harm through stress, oxygen depletion, and injury that compounds the chronic welfare challenges of production.
Pre-slaughter crowding represents an acute welfare harm at the end of a production cycle already characterized by chronic welfare challenges for farmed salmon. The concentration of fish before pumping, stunning, and killing creates a final period of intense stress that compounds accumulated welfare burden. Oxygen depletion in crowded groups causes distress that may itself cause loss of consciousness before stunning — a welfare outcome that could be considered positive if it is painless, but that occurs in an aversive context of extreme crowding. Improving pre-slaughter handling through reduced crowding and oxygenation is achievable and represents one of the highest-leverage welfare interventions available at the end of the production cycle.