It seems odd at a conference where the grand scale impacts of climate change take top billing to get excited about the global warming impact of eating an 8 once salmon steak. But aquaculture is booming – salmon farming is expected to increase 240 fold by 2030 – and the environmental impacts of these activities are not just “a drop in the ocean”. To assess those impacts, speakers here have been looking at the overall environmental burden of fish production, from the pollution of waters resulting from producing fish food, to the emissions of a plane bound for San Francisco from Alaska with a hold full of fresh salmon. And some of their conclusions give food for thought.

In terms of fish food, for example, Nathan Pelletier of Dalhousie University in Halifax, Canada told the audience that the ‘organic’ label on store-bought salmon is not a guarantee that your fish has tread lightly on the sea. Using organic plant ingredients over non-organic ones does reduce the energy intensity and environmental burden of fish food. But what makes a bigger difference is the proportion of plant components (soy, for example) compared to the animal-derived proteins (like fish oils), and the efficiency of the factory that turns fish by-products into oil and meal. These distinctions do not, at present, show up on the food labels at the supermarket.

And if you want your salmon dinner to have had as little impact on the planet as possible, you need to consider not just how it was farmed and fed, but also how it has been processed and transported. Fresh salmon, says Anna Flysjo of the Swedish Institute for Food and Biotechnology in Goteborg, creates more than twice as much greenhouse gas as smoked salmon. That’s thanks almost entirely to the airplane trip that transports it fast from source to seller. Frozen salmon also wracks up a burden thanks to the energy needed to keep it refrigerated on its boat trip. Smoked salmon in cardboard packaging is the way forwards, she says.

Alternatively you can simply live in Alaska, catch a salmon wild and eat it fresh at source. That would be best. Barring that, I think I’ll skip having sushi for dinner tonight.

It seems odd at a conference where the grand scale impacts of climate change take top billing to get excited about the global warming impact of eating an 8 once salmon steak. But aquaculture is booming – salmon farming is expected to increase 240 fold by 2030 – and the environmental impacts of these activities are not just “a drop in the ocean”. To assess those impacts, speakers here have been looking at the overall environmental burden of fish production, from the pollution of waters resulting from producing fish food, to the emissions of a plane bound for San Francisco from Alaska with a hold full of fresh salmon. And some of their conclusions give food for thought.

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