Atlantic salmon farming is a major global industry with significant welfare challenges relating to crowding, sea lice infestations, and slaughter methods.
Farmed Atlantic salmon welfare is compromised by several systemic factors. High stocking densities cause chronic crowding stress with elevated cortisol affecting growth and immune function. Sea lice infestations are ubiquitous in open-net pen farming and cause lesions on the skin and around the eyes. Treatments including hydrogen peroxide baths and mechanical methods like the Hydrolicer cause acute stress. Crowding for treatment is a significant welfare event. Surgical cleaning methods cause wounds. Slaughter welfare has improved with electrical stunning before percussive killing or bleeding now standard in many operations. Pre-slaughter crowding to remove fish from nets causes intense crowding stress. Closed containment systems with water treatment reduce sea lice but require significant investment.