Salmon Farms
The excessive pressures on wild fisheries make a very strong general case for aquaculture - the farming of seafood. But not all seafood farming is equally benign. Farming carnivores such as salmon is particularly questionable since 3 to 5 kg of ecologically valuable food fish are required for every 1 kg of salmon raised. In B.C., the direct impacts of hatchery-incubated disease and parasites on wild fish are compounded by the effects of wastes and toxics released into salmon habitat–equivalent to the raw sewage of a city of 1,000,000 people!
The negative effects of farm-incubated parasitic Sea Lice on wild B.C. salmon are now beyond doubt. The small size of juvenile Pacific salmon makes them vulnerable to even modest concentrations of sea lice, to which they are increasingly exposed when farms are located close to river mouths and along inshore migratory routes. The use of pesticides to treat sea lice has negative impacts on nearby marine organisms.
The failure of Fisheries and Ocean Canada to report the log-known presence of Infectious Salmon Anemia Virus (ISA) in BC wild salmon is ominous. It is clearly benign for the moment, but is known to mutate to deadly virulence. We have seen this happen in Atlantic salmon, and now its presence has been revealed in BC a close watch needs to be kept.
Millions of non-native farmed Atlantic salmon have escaped into B.C. waters, and DNA analysis confirms that some of these fish have successfully spawned in the wild. Atlantic salmon are behaviourally aggressive and compete with wild salmon for habitat and food, and will eat the eggs of local species. The threat is significant and could cause a decrease in the number of successfully hatched wild Pacific salmon each year.
Other issues include the control of predators, other marine species like seals which are inevitably attracted to high concentrations of salmon–many are simply shot, others can become entangled in the containment nets and drown. For all these reason farmed salmon is ranked as unsustainable by SeaChoice–Canada’s most comprehensive sustainable seafood program. SeaChoice provides annual science-based seafood assessments as a resource for consumers.
