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Recirkuleret lakseopdræt med polykultur


The freshwater crustaceans grow well here and are destined to be the key ingredient in a bowl of crayfish bisque at a high-end Vancouver eatery. But they aren't the focus of the Agassiz fish farmer's operation.  Nor is the neighbouring hydroponic vat brimming with watercress or nearby plots growing wasabi and garlic.

They're all happy byproducts of Swift's main enterprise - farming coho salmon on land.It all happens far from salt water on their five-acre property, which looks like any other modest Fraser Valley hobby farm. Rather than discharge the ammonia-laden wastewater from the salmon tanks as effluent, it becomes nutrients for the other crops and for algae that in turn feeds the crayfish.

 "You've got to use those nutrients," Swift says, adding he'd otherwise be like a cattle farmer who makes no use of his manure. The ability to pair salmon with companion crops is one of the attractions of this nouveau aquaculture. "You don't need a lot of room and you can be as innovative as you want," he said. If that's not green enough, the Swifts are working towards a closed-loop system that recycles all water, eliminating the need to draw from a local aquifer.  The coho eat feed made mainly from locally sourced herring meal. No antibiotics or vaccines are used.

And unlike ocean-based net pen farms, there's no risk of pollution, disease spread, the proliferation of sea lice or escapees interbreeding with wild stocks.

 Restaurants, seafood suppliers and other would-be aquaculturists are starting to beat a path to their door. But for many fish consumers, "farmed" is still a dirty word. It's been a long, slow battle against that perception. Five years ago, in his first year of operation, Swift couldn't sell a fish. All the salmon went to a mink farm as animal feed. Today, that's changing.

The couple's coho are an exclusive delicacy on the menu at posh urban eateries like C Restaurant and the Raincity Grill, where they're praised as local, sustainable, healthy and green. "There's so much interest in this land-based salmon farming," Swift said. "A lot of people want to use our coho." The growing demand has the couple contemplating a significant expansion, possibly beyond their current specialty niche market.

 Recently, members of the Cohen Commission were at the site on a field trip, learning about the viability of raising salmon that don't depend on the ecology of the ocean or river. The commission will hear intense criticism of net pens and growing calls for a shift to land-based systems. A new report from the Save Our Salmon Marine Conservation Foundation concluded there's a good business case for closed-containment fish farming on land, judging it both eco-friendly and profitable.

 Still, Swift won't criticize the saltwater net pens used by conventional salmon farms. "We don't do this because we have some agenda against salmon farming," Swift said.  Growing salmon in fresh water tanks has its differences and trade-offs, he notes. The absence of wild ocean food means the land-farmed coho flesh is white in colour. As a result, Swift adds a naturally derived pigment to their food to give them the characteristic red coho colour. No customer will buy a white-fleshed salmon, he explains. They can also be grown on entirely vegetarian grain-based feed, but that subtly alters the taste. Swift uses coho not sockeye because they grow faster - from egg to market weight in two years - and are less prone to stress and disease.

The Swifts aren't just pioneers but also apostles of fish farming, helping others get into the business. And there's plenty of interest. Alberta livestock farmers want their help converting pig barns to farm salmon or even a tropical Asian fish called barramundi. Several B.C. First Nations see potential to employ band members to farm salmon. The Swifts are even working with a Hutterite community in Montana. Much of the coho that they grow are for brood stock to produce eggs to set up new operators.

"We're almost creating an industry," Swift said. "Over the next 10 years, I think you'll see a lot of land-based salmon farms. "As we yearn for a fish diet, a healthier omega-3 diet, there's a lot more than just rainbow trout that we can use."

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