Stocking density is one of the most critical welfare determinants in Atlantic salmon farming. Understanding the physiological and behavioural impacts of crowding guides welfare-positive stocking management.
Crowding stress in farmed salmon represents a chronic welfare burden affecting every aspect of the animals' physiology and behaviour. Chronically elevated cortisol impairs immune function, increasing disease susceptibility; competition-induced fin damage creates open wounds; and the constant presence of conspecifics at unnaturally high densities prevents the spatial distribution that salmon naturally maintain. The welfare and production interests align more closely than often recognised: overcrowded salmon have poorer feed conversion, higher mortality, and lower flesh quality. The transition to lower stocking densities is the most direct and impactful welfare intervention available to salmon producers, and the economic barriers to this transition are less than frequently claimed.