WILD salmon could be succumbing to a plague of parasites because salmon farms are nullifying an adaptation that usually protects young fish from infestation.
Ordinarily, juvenile salmon never encounter adults during the first few months of their migration from rivers into the ocean, because adults live far out at sea. Fish farms, which rear mature salmon in net pens near the shore, break down that ecological separation, and this may have contributed to the decline of salmon populations.
To investigate, Martin KrkoÇsek of the University of Alberta in Edmonton, Canada, and colleagues looked at juvenile salmon migrating along the coast…
