Salmon farms spread deadly lice to wild salmon.

• Author: Herro, Alana
• Position: Brief article

Salmon farms can pass fatal infections of sea lice (small parasitic crustaceans) to young salmon in the wild, according to a study published October 4 in the Proceedings of the National Academy of Sciences. The research, conducted in British Columbia's Broughton Archipelago, provides the most direct evidence yet that the increase in salmon farming results in more wild salmon deaths.

According to the report, sea lice that originate in the crowded conditions of fish farms can cause mortality rates of up to 95 percent in baby wild salmon populations. A single parasite can attach to a juvenile 2.5-centimeter salmon and kill it. While adult salmon carry the parasitic lice, they are able to survive because of their size and protective scales. In natural conditions, adult salmon also typically live offshore, away from the migratory routes of younger salmon.

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Salmon farms, in contrast, house hundreds of thousands of adult fish in floating pens that are anchored in natural migratory channels, a situation that causes baby wild salmon...