[ Developing Ideas Digest ][ IISDnet Contents ]

About Di Digest | Back Issues | Mailing List | Email DI | On Line Features 1 | 2 | 3 | 4 | 5 |
LitScan
TrendWatch
TrendWatch

Closed-Loop Salmon Farming

Diseased and depleted fish stocks, new antibiotic-resistant viruses, and possible genetic abnormalities are some of the dangers associated with open-pen salmon farming. In Norway, Scotland and Ireland - and more recently on the west coast of Canada - coastal communities have been raising the alarm on what they see as a major environmental threat posed by the burgeoning cultivated salmon industry. David Hocking, communications director of the David Suzuki Foundation in British Columbia, likens net-pen salmon farming to the gigantic cattle feed-lots on the Prairies, where large numbers of cows are herded together to feed in a small area piled high with manure that leaves an olfactory impression for miles around. The major difference between fish farms and feed lots, said Hocking in a telephone interview with DI, is that the salmon pens "are floating in an ocean, floating in a wild environment. With a cattle feed lot, you are able to contain the feces to some degree, you don't have currents of water that are moving it in and out of the cow cage. You also don't have wild cows roaming nearby, who can pick up the diseases from the caged cows." But that is what happens with net-penned salmon, as has been documented in several countries. Penned salmon pick up diseases from the wild, and the effects are magnified because of the confined, stressful conditions in the fish farms. When the diseases are passed back to the wild fish, they are more virulent and can have a devastating effect on wild stocks. Antibiotics (fed to penned salmon to help them resist disease) and antibiotic-laden fish feces also float out into the wild environment, creating antibiotic resistant organisms that may be passed along to humans through seafood. In addition, there are fears that genetic abnormalities could occur if different strains of salmon started to mate. In BC, for example, penned Atlantic salmon routinely break free and swim among Pacific salmon. Now a coalition of environmental groups and Aboriginal communities in British Columbia believe they have a solution. They are calling for the development and mandatory use of "closed-loop containment systems" for the farming of salmon. A prototype closed-loop system has been recently developed. Constructed of fibre-glass and containing internal floatation devices to create a neutral buoyancy, it floats upon the water. With walls extending about six feet above the surface, no water from the outside can get in. And with a closed bottom like that of a bathtub, no water can escape accidentally - although water can be released after undergoing a sewage treatment process. Hocking believes that requiring fish farmers to use closed-loop systems is a better option than that recommended by a recent provincial government study, which called for the creation of a new bureaucracy to control the environmental impacts of fish farms. "What we say is, don't try to police, at public expense, a system that is essentially unsustainable from an ecological perspective. Instead, figure out a solution that works ecologically, insist that people use it, and then you are putting the cost of compliance on the industry. The industry has to assume the ecological externalities rather than the public," he says.