The ecological impact of salmon farms on wild fish populations has welfare implications for billions of wild fish affected by farm-derived sea lice and pathogens.
The welfare of wild salmon affected by sea lice from farms represents a population-scale welfare harm rarely discussed in aquaculture welfare conversations. When juvenile wild salmon pass by farm cages and acquire heavy lice infestations, they experience the same welfare impairment as farmed fish — skin damage, osmotic disruption, secondary infections — with the additional consequence of reduced survival that has conservation implications. The welfare of billions of wild fish affected by aquaculture industry externalities is a legitimate welfare concern that extends the moral calculus of seafood choice beyond the farmed fish themselves. Choosing farmed salmon from closed containment or inland recirculating systems eliminates these wild fish welfare impacts.