Farm a salmon, farm their parasites

My brother is visiting from New York, and he brought with him sweet manna from heaven – H&H bagels. So I dashed out to buy the traditional bagel toppings (I’m pretty sure the ancient Israelites ate these while crossing the Sinai desert) – cream cheese, tomatoes, red onions, and of course lox. Because what’s bagels without some tasty smoked salmon?

Then the NY Times had to go ruin all my joy. A new study in Science reports that salmon farms in Canada are breeding so many parasites that they are killing more than half of wild salmon young. The parasites are fish lice, a crustacean that works like a tick – it hangs onto the fish and drinks its blood. Unfortunately for the juvenile salmon, the fish lice are proportionately much bigger than a tick – as one of the researchers said on NPR, it’s like having a bloodsucking parasite the size of a raccoon, and an individual salmon can carry several lice. This huge parasite load is killing an unbelievable 8 out of 10 juvenile pink salmon (the smallest and most common salmon species). At this rate, researchers estimate that Canadian runs of pink salmon will be extinct in 4 years.

I was lucky enough last year to have lunch with the eminent fisheries biologist Ram Myers, just a few months before his death. He was convinced that the biggest threat to the health of the oceans was not overfishing, not climate change, but the growth of aquaculture. I was confused, and to be honest, though him a bit daft – wasn’t aquaculture supposed to alleviate some of the pressure on the ocean? Wasn’t some aquaculture environmentally responsible? Dr. Myers said no, none of it would end well, because of the parasites. We never give parasites enough credit, he said. As in so many things, it appears he was prescient.

No informed environmentalists advocate salmon farming. Salmon are highly active predators, and vast quantities of smaller fish must be caught to feed them. They must be dosed with antibiotics and their flesh must be dyed pink artificially. This study should be the nail in the salmon-farming coffin. There’s just too many people wanting to eat too high up the food chain. The only way to win is for those of us who love our meat to go lower. I hear that mussels are very nice smoked – perhaps they would go well on my wonderful sweet glorious sesame-seed bagel.

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One Response to Farm a salmon, farm their parasites

  1. jebyrnes says:

    Parasites truly rule the world. I saw Kevin Lafferty give a talk in which he calculated the biomass of parasites in Carpenteria salt marsh – a pretty small little marsh near Santa Barbara – roughly 1m^2 I think. It comes out to be the same as three elephants. Can you picture THREE ELEPHANTS all trapped in 1 square mile, doing their elephant thang all day everyday? And this is without even thinking about the asymmetry of most parasite-host interactions.

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