Cataracts affecting the lens of Atlantic salmon are widespread in aquaculture and cause significant welfare harm by impairing vision, feeding ability, and navigation. Nutritional and management interventions can substantially reduce prevalence.
Cataracts in farmed salmon represent a preventable welfare problem. Impaired vision affects a fish's ability to locate feed, interact normally with conspecifics, and respond to environmental cues. Fish with cataracts in high-density sea pens experience impaired feeding competition, reduced condition, and increased susceptibility to other health problems. The fact that nutritional cataracts are almost entirely preventable through adequate histidine supplementation makes their continued prevalence a clear welfare governance failure. Industry-level commitment to preventive nutrition standards would eliminate most cataract cases.