Atlantic salmon are social, schooling fish whose natural behaviour has welfare implications for pen design and stocking management in aquaculture.
Salmon schooling behaviour offers a welfare monitoring opportunity that is being actively developed for commercial application. Normal schooling represents a baseline positive welfare state; disrupted schooling with surface swimming, erratic movement, and group fragmentation indicates welfare compromise that can signal disease, water quality problems, or stocking density stress. Technology enabling automated school behaviour monitoring provides continuous welfare surveillance that manual inspection cannot achieve. The welfare implications of school disruption extend beyond individual fish to the social information network that schooling provides: disrupted schools lose collective threat detection and energy-efficient coordinated movement that are fundamental to salmonid evolved ecology.