Environmental conditions in salmon and trout net pens including water temperature, oxygen levels, and current affect fish welfare and require active management.
Net pen fish face an environmental welfare challenge that wild fish do not: inability to move away from adverse conditions. Wild salmon experiencing oxygen depletion, temperature stress, or harmful algal blooms can simply swim elsewhere. Net pen fish experiencing the same conditions cannot escape. This creates an obligation on farmers to actively manage the environmental conditions to which fish are confined. Monitoring systems that detect oxygen depletion, temperature anomalies, and algal bloom indicators before they reach welfare-relevant levels allow preventive management. Submersible systems and deep feeding pipes that give fish access to better water quality conditions address thermal and oxygen stress without requiring farm relocation.