Farmed salmon escapes and sea lice transmission affect wild salmon populations, creating conservation welfare concerns beyond individual farmed fish.
The welfare of wild salmon affected by salmon farming represents a population-level welfare concern extending beyond the individual animals in aquaculture pens. Sea lice amplified by dense farm populations cause welfare harm to wild salmon and sea trout migrating through affected coastal waters — elevated louse burdens cause skin damage, immune suppression, and reduced survival. Escaped farm salmon may introduce diseases and genetic dilution that reduce wild population fitness over generations. Closed containment systems that physically prevent escape and eliminate sea lice export to wild populations offer the most comprehensive solution to these population welfare concerns, at the cost of higher production costs that are only partially reflected in current market pricing.