How proximity of open-water salmon farms to wild salmon migration routes creates welfare and conservation risks for both populations.
The welfare and conservation impacts of open-water salmon farming interact in ways that compound both harms. Wild smolts passing through sea lice blooms near farms experience the acute and chronic welfare harm of heavy ectoparasite infestation, and those that survive often join spawning populations with reduced genetic fitness from escaped farm salmon hybridisation. The solution — closed-containment inland RAS — is technically proven but economically challenging. In the interim, regulatory controls on farm placement relative to wild salmon migration routes, mandatory sea lice count transparency and effective escape prevention are the minimum standards required to reduce the externalities that open-water farming imposes on wild fish welfare and conservation.