Atlantic salmon are social fish that exhibit complex group behaviors in the wild. Understanding their social needs is key to improving welfare in aquaculture settings where crowding and competition create stress.
The social environment of farmed salmon profoundly affects their welfare. Chronic crowding activates stress pathways, suppresses immune function, and forces subordinate fish into states of ongoing defeat stress. While individual fish may not show obvious signs of distress, population-level welfare indicators reveal significant suffering in high-density systems. Improved stocking density standards, environmental enrichment, and selection for less aggressive strains are all promising pathways to reducing the welfare burden in salmon aquaculture.