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Is Farming Salmon Like Herding Cats?

July 11, 2008

In some ways, yes, except of course that the goal is to eat the salmon (not the cats).

In the wild, salmon leave the ocean, swim hundreds of miles upstream—sometimes up waterfalls—to return to their natal spawning grounds year after year. So it makes sense that these persistent fish easily bust out of their pens when you try to corral them. In fact, this week, 30,000 farmed Atlantic salmon did just that, escaping from their coastal British Columbia pen into the Pacific Ocean. 

The presence of rogue farmed salmon is bad news for the already depleted stocks of wild salmon in the Pacific. (Many Pacific runs are closed to fishing this year due to ridiculously low population counts.) The escapees compete with the wild fish for food, something the wild fish have been struggling to find in the last few years thanks to changing ocean conditions. (Few or weak upwellings haven’t brought enough nutrients to the surface to sustain the salmon’s food sources.) And then of course, once the farmed and wild salmon start mingling, they start mating. This can lead to trouble.

Wild salmon have evolved to survive in the ocean and navigate back to their individual spawning river by swimming miles upriver, leaping up waterfalls and doing it all at the right time of year. Farmed salmon have been bred to grow quickly, that’s pretty much it.  So when the two get together they create a hybrid salmon whose chances of survival are significantly lower than that of its wild parent.

Even when the fish are nicely contained in their pens, salmon farms can do serious damage to wild salmon that swim nearby. In fact, scientists have found that the chances of wild fish surviving and returning to their natal spawning grounds drops by more than 50% when the fish migrate past a salmon farm.

Wondering how the farmed salmon manage to knock off their free-swimming relatives? They don’t. The louse does.

Sea lice (plural of louse) occur naturally in the ocean. As parasites with a penchant for salmon, they drift through the ocean looking for a host fish. When they find one, they latch on and go to town doing their parasite thing (i.e. feeding on skin, muscle and blood). And when they find thousands (or millions) of fish in a salmon farm, they have a field day. But that doesn’t mean they’re satisfied. When an unsuspecting wild salmon swims near a salmon farm festering with sea lice, the lice hop onboard.

Adult salmon have thick scales that make sea lice infestations bearable (or at least survivable). Juvenile salmon aren’t so lucky. The sea lice attack these little guys with the same gusto they use on the adults, but juveniles don’t have scales to defend themselves. Sea lice eat through the juveniles’ skin, leaving them vulnerable to deadly infections.

It’s not just the salmon and the louse. The whole salmon farming operation is a bit of an environmental nightmare. Salmon are carnivores so they need to eat lots of fish to grow up big and juicy. On average, it takes 2.5 kg of wild-caught fish to produce 1kg of farmed salmon. While the farms are taking plenty of fish from the ocean, they’re also putting plenty of crap (literally), antibiotics, feed additives and toxic chemicals into the surrounding waters.

Of course, this pollution isn’t pretty, but salmon farms aren’t petting zoos. They’re protein-producing machines. Salmon is delicious—especially with a maple ginger glaze—and it’s filled with lots of good-for-you things like omega 3 fatty acids. But should you eat farmed salmon? As you now know, the current style of salmon farming threatens wild salmon populations and the marine environment as a whole. In other words, it’s unhealthy for the environment.

But is farmed salmon a healthy food choice for people? Not particularly. The nutritional supplements used in aquaculture are typically high in persistent organic pollutants like PCBs and dioxins so farmed salmon have higher contaminant levels than wild salmon. And farmed salmon are filled with antibiotics to keep them from infecting one another while living in close quarters. Oh, and one more thing: wild salmon flesh turns pink from the food they eat. The pink color in farmed salmon—it’s fake. 


One Comment leave one →
  1. August 7, 2008 10:58 pm

    Hi guys — great post!

    I work for the Coastal Alliance for Aquaculture Reform (specifically on their markets campaign, called Wild Salmon Supporters) and we would love it if you wouldn’t mind putting up a link or one of our web badges. Email me if you’re interested!

    Thanks, and keep up the great work!

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