Salmon Farming Threatens Wild Populations

Vulnerable young wild salmon traveling on migration routes that pass through open-net salmon farming pens are increasingly being killed off by the sea lice parasite. Photo: John Volpe/University of Alberta

As the federal government and the aquaculture industry push for expanded fish farming along coastal areas, a new study reports that the intensive farming of salmon is putting several wild salmon populations at risk of extinction. It is the most detailed report ever to be done on the issue—pointing out a direct connection between the aquaculture industry's rapid growth in the Broughton Archipelago off British Columbia and the sharp decline in its wild pink salmon due to an infestation in open-net salmon pens by sea lice. Though older salmon can handle the parasite, young wild salmon migrating through these areas are much more vulnerable. "In the natural system, the youngest salmon are not exposed to sea lice because the adult salmon that carry the parasite are offshore," said study co-author and Salmon Coast Field Station director Alexandra Morton. "[F]ish farms cause a deadly collision between the vulnerable young salmon and sea lice. They are not equipped to survive this, and they don't."