Atlantic cod were once the most abundant fish in the North Atlantic. After catastrophic wild population collapses, aquaculture is being developed as an alternative supply — but welfare challenges and ecological questions remain unresolved.
Atlantic cod welfare in aquaculture is shaped by the species' naturally aggressive and cannibalistic behaviour at high densities. Size grading — frequent sorting of fish by size to reduce cannibalism — creates repeated handling stress throughout the production cycle. Light manipulation to control reproductive cycling represents a form of environmental control that alters the cod's natural biological rhythms. At commercial stocking densities, stereotypic swimming behaviours indicate chronic stress. Slaughter welfare is variable: ice slurry immersion without prior stunning causes prolonged conscious suffering, while CO2 anaesthesia — while sometimes used — is aversive at effective concentrations. The ecological question of whether farmed cod actually reduces pressure on wild stocks — or simply creates additional market demand — is relevant to the welfare calculus: if farming displaces wild harvest, the net animal welfare benefit is positive; if it adds to overall demand, the benefit is reduced.