Atlantic salmon farming is a global industry producing over 2.5 million tonnes annually. The welfare challenges involved affect billions of fish and have attracted growing scientific and public attention.
Farmed salmon welfare challenges operate at an almost incomprehensible scale — each production cycle involves hundreds of millions of individual fish. Sea lice are the most visible welfare problem: the parasites cause open wounds, impair osmoregulation, and in severe infestations can be lethal. Treatment involves chemical bath treatments, lasers, or mechanical delousing — all of which cause additional acute stress. Crowding stress suppresses immunity and increases disease susceptibility in a vicious cycle. Welfare at slaughter varies dramatically between facilities, with some using well-evidenced percussive stunning and others still relying on chilling or CO2 exposure that may not render fish unconscious before killing. Consumer pressure and NGO campaigns have driven some improvement, but the structural economics of intensive salmon farming create persistent pressure against welfare investment.