Last Wednesday, strong ocean currents shifted an anchor on one of 12 pens in a salmon farm near B.C.'s Campbell River, causing the anchor to fall into a crevice. The anchor pulled down a net with it, creating an opening through which the salmon escaped.
The Norwegian seafood giant, Marine Harvest, which owns the farm, says the escaped fish pose no danger to native stocks. The Canadian broadcaster CBC quotes Clare Backman, the company's director of environmental compliance and community relations, who says that the fish are healthy:
"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," Backman said.
But others aren't so sure. The Globe and Mail, a Canadian national daily, quotes Jennifer Lash, the executive director of the Living Oceans Society, a nonprofit that calls for an end to open-net cage salmon farms. Ms. Lash says that if the Atlantic salmon breed, they will compete with wild salmon, whose populations have plummeted in recent years.
"You get juvenile Atlantics, they're not indigenous to the [Pacific] coast and they start competing with the wild salmon and they start putting the wild salmon at risk. Everything has to be done to stop having those Atlantic salmon in the ocean," she said. "Any time you bring in an invasive species or a non-indigenous species ... it poses a threat to the existing biological diversity."
Farmed Atlantic salmon lack many of the instincts of wild salmon, but they have been bred to be voracious eaters, according to Raincoast Research biologist Alexandra Morton, who spoke with the Globe and Mail. Morton says that the escaped salmon are likely to dine on the wild salmon's food supply, or even on young wild salmon. Ms. Morton also said that the Atlantic salmon tends to favor the same spawning grounds as steelhead – the Pacific species most closely related to the Atlantic salmon. In the past, escaped Atlantic salmon have shown evidence of fights with steelhead.
Also of particular concern are sea lice, parasitic crustaceans that tend to flourish in salmon farms. In 2005, a study of wild and farmed salmon in the Pacific Northwest found that wild salmon swimming near fish farms showed higher rates of the potentially deadly infestation. Marine Harvest told the Globe and Mail that the pen from which the salmon escaped had low levels of sea lice.
Canada's Environment Ministry is investigating the escape. A written report from the company is expected Tuesday, and the government has not ruled out pressing charges.
Conservation groups have long called for open-net cage salmon farms to be replaced by closed containment tanks, which would not only protect local ecosystems but would also protect the farmed salmon from marine mammals such as sea lions.
In the meantime, Marine Harvest wishes bon appétit to anyone who catches the escaped fish. "They should keep the fish, clean it, and bake in a 400-degree F. oven with a ginger and green-onion garnish," said Mr. Backman in an e-mail to the Globe and Mail. "Then serve with fresh lemon slices."