Atlantic salmon aquaculture involves high stocking densities in sea pens that cause aggression, disease pressure, and chronic stress — welfare concerns that the industry is beginning to acknowledge and address.
Atlantic salmon in high-density sea cages experience a cascade of welfare problems rooted in overcrowding. Aggression between fish causes fin erosion and eye injuries. Sea lice infestations cause chronic irritation and skin damage. Crowding stress elevates cortisol and impairs immune responses. The industry is under increasing pressure to adopt welfare indicators and reduce stocking densities, driven partly by consumer pressure and partly by Norwegian regulatory reform. The welfare of salmon in aquaculture is one of the most numerically significant animal welfare issues globally.