Escapes from salmon aquaculture facilities release millions of farmed fish into wild river systems — with welfare consequences for both escaped farmed fish and the wild populations they interact with.
Escaped farmed salmon face profound welfare challenges in the wild. Domesticated over many generations for growth in aquaculture conditions, they are poorly adapted to wild survival — unable to navigate river systems, find natural food, or compete effectively with wild conspecifics. Most starve or are rapidly predated. Those that survive long enough to attempt spawning carry genetic traits that reduce offspring survival when hybridized with wild fish. The welfare harm of escape is acute for individual farmed fish and chronic for wild populations whose fitness is diluted.