Where aquaculture facilities are sited determines their impact on wild fish welfare and ecosystem health, with exposed offshore sites generally causing less ecological harm than sheltered bays.
Aquaculture siting decisions affect wild fish welfare through two primary pathways: waste accumulation that depletes oxygen and harms benthic communities, and parasite transmission that burdens wild fish passing near farm sites. Farms sited in sheltered bays with low water exchange create oxygen depletion zones in surrounding sediments that cause mass mortality of bottom-dwelling invertebrates and fish. Salmon farms positioned on wild salmon migration routes expose juvenile wild salmon to elevated sea lice burdens that reduce their survival. Regulatory frameworks that require impact assessments, buffer zones from sensitive habitats, and open-water circulation standards address these welfare implications. Offshore farms and recirculating systems avoid them entirely.