Although David’s reply contains much interesting information, I’m not sure if he read your article correctly as you say “fish farms do not disturb the marine ecosystem AS MUCH as other commercial methods” and the article points out that fish farms can have a negative impact. Or is he saying that fish farms are more destructive than other fishing methods??

Take a look at what is happening to marine ecosystems in British Columbia, Norway and Chile as a result of open-net pen salmon farming.

For one, sea lice, attracted by tens of thousands of net-caged salmon proliferate and spread to wild salmon stocks. This proliferation of sea lice has contributed to the decline of wild salmon stocks, because the clouds of lice attack juveniles on the way out to sea, overwhelming them or impairing them and so making them easier prey to predators.

Waste, in the form of fish feces and unconsumed feed, can build up under the pens smothering portions of the ocean bottom, contaminating the marine ecosystem and depriving species of oxygen. Or the bulk of waste may be carried away from the farm site by ocean currents, but this too ends up collecting in another place and causing localized pollution. Clam beaches used by First Nations in the Broughton Archipelago (the area with the highest concentration of salmon farms in BC) have been destroyed by the accumulation of black muck and sludge that has been attributed to salmon farm waste.

The predominate species of salmon raised in these operations is Atlantic Salmon, escapes of this species in BC can pose a serious threat to local Pacific species as they have the potential to out-compete wild salmon for habitat and food and transfer disease and pathogens to wild salmon.

A major impact of fish farming of carnivorous species that is often overlooked is the feed- between 1.5 to 8 kg of feed is required for every kg of farmed fish, depending on the species and feed mix. Contrary to the industry’s claims, they are not taking pressure off of wild fish stocks but are contributing to it, and incresingly so as the industry expands. The species used for feed include herring, anchovies and sardines and often come from Southern fisheries and diverted to the feed industry to grow farmed product for Northern markets, taking away an available local protein source.

Finfish aquaculture does hold potential, however, but only if it eliminates its impact on wild stocks and marine ecosystems. A move to closed containment systems, preferably land based, could accomplish this.