Escaped farmed salmon pose ecological threats to wild populations while escapement events themselves indicate welfare failures within aquaculture systems.
Escapement events represent acute welfare failures: salmon escaping through torn nets or during storm damage typically sustain injuries including scale loss, abrasion wounds, and barotrauma from pressure changes. Before escaping, fish in damaged cages may experience crowding, oxygen depletion, and handling stress as crews attempt repairs. Post-escape, farmed salmon face an unfamiliar environment for which their genetics and condition may be poorly suited. The welfare case for RAS land-based systems includes elimination of storm exposure, net damage events, and sea lice burden — though RAS introduces different welfare considerations around water quality management. Preventive maintenance programmes that inspect net integrity before storms prevent both ecological harm and acute escape-event welfare impacts.