In the Broughton there are just too many farmed fish in the water. If there were only one salmon farm this problem probably wouldnt exist, Krkosek says.
Over the years the number of farmed fish has increased, says Morton. There used to be only a few farms, each holding about 125,000 fish. But now we have over 20 farms, some holding 1.3 million fish. The farmed fish are providing a habitat for lice that wasnt there before.
The researchers observed that when farms on a primary migration route were temporarily shut down, or fallowed, sea lice numbers dropped and salmon populations increased. Even though they have complicated migration patterns they all have one thing in common overall, the populations that are declining are the ones that are going past the farms, says Mark Lewis, a mathematical ecologist at the University of Alberta.
There are two solutions that may work closed containment, and moving farms away from rivers, says Lewis. Closed containment means moving the salmon to pens that are completely sealed off from the surrounding environment in contrast to the open-net pens currently in use. In a May 16, 2007 provincial government report, the B.C. Special Committee on Sustainable Aquaculture recommended a move towards closed containment within 5 years.
If industry says its too expensive to move the fish farms or contain them, they are actually saying the natural system must continue to pay the price, says Daniel Pauly, Director of the University of British Columbias Fisheries Centre, who was not involved with the study. They are, as economists would say, externalizing the costs of fish farming on the wild salmon and the public.
|Contact: Matt Wright|