All is Not Well With Salmon Farming

by Ray Grigg

All is not well with salmon farming. The industry presents a front of confidence and optimism but behind the public relations image is a reality of threat and fear. The situation in Norway, the country from which the industry spread to Scotland, Chile and Canada’s East and West Coasts, is an indicator of the direction the industry is heading.

In Norwegian salmon farms, viral diseases are proliferating and sea lice are developing resistance to the pesticide of choice, emamectin benzoate (aka SLICE). With increasing frequency, sea lice-infected farmed salmon must now be bathed in a hydrogen peroxide solution to cleanse them of the parasite. This is also becoming the practice in Chile, Nova Scotia and BC. Once allowed for use in Canada only through the Emergency Drug Release Program as a treatment of last resort, SLICE became a routinely applied chemical in June 2009. It is now becoming ineffective.

Although escaped farmed Atlantic salmon do not seem to be a major problem in BC where they are not native, in Norway and Canada’s Maritimes their damage to the native Atlantics may be serious and irreversible. The Norwegian Institute for Nature Research recently tested 20,000 Atlantics in 147 Norwegian rivers and found that, in 109 of these rivers, up to 50% of the wild fish and up to 42.2% of their genes were altered by interbreeding, a genetic contamination that could impair the viability of the wild fish. This would be a serious threat to wild Atlantics in Canada’s Maritimes.

In Chile, which does not have native salmon, about 20% of farmed fish are once again dying from an outbreak of the infectious salmon anemia virus (ISAv), the disease that spread throughout its industry between 2007 and 2009, killing millions of salmon, costing the industry $2 billion, and shocking Chile’s economic and social structure. Heavy antibiotic use is now promoting drug resistant super-viruses.

The latest disaster for Chilean salmon farms has been a toxic algal bloom. The “red tide” has poisoned about 2,000 kilometres of coast, killed uncounted tonnes of wild fish, contaminated shellfish, and been fatal to both people and marine mammals. The environmental catastrophe has stimulated riots and allegations of criminal wrongdoing. Chilean biologists are implicating the salmon farming industry in the spread of the bloom because the supply of fecal nutrients beneath the many open net-pens promotes algal growth, and because more nutrients were added when about half of the estimated 100,000 tonnes of dead salmon were left to rot in the sea. An additional 150 million farmed salmon are now at risk from further algal blooms, the recurring ISA virus and the ongoing sea-lice epidemic.

Meanwhile, in British Columbia, tonnes of farmed salmon in Clayoquot Sound and other facilities have died from toxic algal blooms and low oxygen conditions. Uncontrollable sea-lice infections are requiring hydrogen peroxide baths, piscine reovirus is now epidemic in farmed fish, HSMI (heart and skeletal muscle inflammation) has been found, ISAv and many other viruses threaten, First Nations are issuing eviction notices to the industry for trespass in their unceded territories, and scientists — the accumulating evidence suggests — are getting closer to linking salmon farms with transferring viral infections to wild salmon.

In summary, salmon farming is an industry under threat.