Atlantic salmon in intensive net pen aquaculture face a range of welfare challenges including sea lice infestations, crowding stress, and the mismatch between their evolved migratory instincts and captive conditions.
Farmed salmon welfare involves a combination of disease challenges and behavioral restriction. Sea lice — small parasitic crustaceans — cause chronic stress and tissue damage that can be severe in affected fish. Treatment methods including chemical baths and physical delousing devices themselves cause acute stress and injury. Improved genetics for sea lice resistance, closed containment systems, and lower stocking densities represent welfare improvements that are increasingly economically viable. Consumer certification schemes and procurement policies are the primary drivers of welfare improvement in this sector.