Fish Farming

Fish Farming

Fish Farming

Fish is a part of any healthy diet, right? Not necessarily, says University of Alberta fisheries ecologist Dr. John Volpe, who believes the farmed salmon found on supermarket shelves represent a major environmental threat and probably aren't good for you.

It isn't widely known on the Prairies, but almost all of the fresh salmon sold at supermarkets and served at restaurants is grown in one of approximately 100 ocean-based salmon farms that dot the waters off the British Columbia West Coast. The salmon, Volpe says, have high concentrations of toxins because of their diet--the salmon farming industry feeds their stocks a high-fat diet, he says.

The fat in that diet comes from fish like mackerel and anchovies harvested from southern oceans. When the catch is processed, its fatty content is separated to form a major ingredient in the food fed to farmed salmon--along with antibiotics and a synthesized chemical that give the fish a healthy-looking, pink glow.

The trouble with that diet, says Volpe, is that toxins, like dioxins and PCBs, are stored in fat. By feeding their captive fish high-fat diets, farmers are also multiplying the amount of toxins they'd ingest in the wild. At the same time, he observes, South American fisheries are being depleted in order to feed farmed fish, which are grown to compensate for the collapse of North American fisheries.

It gets worse. According to Volpe, a salmon absorbs only 15 to 17 per cent of the nutrients it eats--the rest of it is excreted and falls to the ocean floor along with food that isn't even consumed in the first place. The fish are hemmed in nets and farmed in close, crowded conditions; Atlantic salmon are farmed because they survive such conditions better than Pacific salmon do.

But farm fish escape when animals or boats rip holes in the enclosures. Last year, Volpe published a report that showed escaped Atlantic salmon are surviving and spawning in Pacific salmon territory, and he fears...

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