European sea bass (Dicentrarchus labrax) is a major aquaculture species whose welfare is significantly affected by stocking density and susceptibility to bacterial disease.
Sea bass demonstrate pain responses, fear conditioning, and stress physiology comparable to terrestrial vertebrates, making their welfare a serious concern in intensive aquaculture. High stocking densities cause chronic stress through disrupted social hierarchies, increased aggression, and resource competition. Chronic stress suppresses immunity, increasing disease susceptibility and antibiotic use. Welfare improvements include reduced stocking densities, environmental enrichment such as structured refuges, optimised feeding regimes, and improved slaughter methods including electrical stunning. The EU Aquaculture Strategy and RSPCA Assured certification for sea bass include density limits and welfare monitoring requirements. Welfare assessment protocols developed by the FISHWELL project provide validated indicators.