High stocking densities in salmon aquaculture are associated with chronic stress, aggression, and increased disease susceptibility.
Salmon are active, wide-ranging fish that in the wild experience large territories and varied environments. High-density farming forces them into sustained proximity that elevates chronic stress markers, impairs immune function, and increases aggressive interactions. Cataracts, a common welfare problem in farmed salmon, are partly associated with crowding and dietary factors. Reducing stocking densities is one of the most evidence-based interventions available to improve farmed salmon welfare at scale.