Atlantic Salmon Escape

Ocean net pen. Courtesy of British Columbia
Salmon Farmers Association

By Nina Bubert

Strong ocean currents caused nearly 30,000 Atlantic salmon to escape from a net pen farm in British Columbia near the Campbell River on Canada Day, 1 July.  Workers had to watch helplessly as the net pen anchor shifted and fell into a crevice, lest they be pulled in with it.  The net pen system was stabilized three days later and recovery efforts only yielded about 400 salmon.

Marine Harvest, the Norway-based company that owns the farm, seemed more concerned with the estimated half a million dollar loss then the potential environmental costs. 

“There’s no ability for these fish to spread anything to the wild salmon. First of all, they are quite healthy. They haven’t needed any antibiotics. They haven’t contracted any diseases at all. They are perfectly healthy fish that were scheduled to go to market within the next two to six months,” said Clare Backman, the Director of Environmental Compliance and Community Relations for the local office of Marine Harvest.

Even if this is the case, a healthy invasive species could potentially be just as harmful to native wild populations as a diseased animal.  Atlantic salmon represents an unnatural competition to wild salmon for food and spawning grounds. Atlantic salmon could likely colonize areas because unlike Pacific salmon they may spawn several times whereas Pacific salmon die soon after spawning.  This unwelcomed visitor to the Pacific may even hybridize with native salmon which could result in loss of genetic diversity, increased disease outbreaks, and possibly extinction. 

Salmon farming began in the 1970s on the Pacific Northwest.  This was seen as a potential solution for predicted future demand for seafood based on population growth estimates.  By the 1980s Atlantic salmon began to be farmed and by the 1990s salmon farming was a booming industry.     

The issue of escapes of non-native species is just one of many environmental concerns. Effluents from fish farms, which include fish waste, delousing chemicals, antibiotics, and uneaten food, can cause biological dead zones and environmental harm to the ocean bottom directly below and the areas surrounding the pens.

In addition to waste and disease that can spread to the surrounding environment, transfer of parasites from open net pens remains a concern in salmon farming operations. Sea lice from fish farms have caused catastrophic declines in runs of wild pink salmon in British Columbia. Sea lice, a naturally occurring parasite on adult salmon, latch onto juvenile pink salmon when they are migrating near fish farms on their way out to the ocean.

Often in fish farming, the environmental impacts are less direct. For instance, most species used in fish farming operations are carnivorous and require a large amount of protein, usually obtained from wild forage fish stocks that both wild fish and other organisms, including marine mammals and birds, depend on for food. While aquaculture companies have begun to substitute soy protein and other vegetable proteins into their feed, the use of wild fish in their feeds remains a problem and an environmental concern that has yet to be resolved.

The recent closures on salmon fishing have many worried about the future of this biologically important species.  We need to increase awareness about the damaging effects of farming Atlantic salmon in the Pacific Northwest.  Canadian and US governments need to work together to ensure future escapes do not occur.   

 

Ocean salmon farm photo: Courtesy of National Geographic