buying frozen

I hear a lot about how to be better — in terms of a number of factors, but largely sustainability — about my eating habits.  Buy organic.  Buy local.  Eat less meat.  Buy wild fish — caught sustainably — instead of farmed. But here’s one I hadn’t heard before — buy frozen.

Some recent research (NYT article— may require login; Environmental Science & Technology paper – requires subscription; Ecotrust press release — freely accessible) indicates that, in terms of salmon, buying fish that is flash-frozen at sea prior to shipment (instead of shipped fresh to markets or restaurants) makes a bigger environmental impact than any other factor.

The reason: Most salmon consumers live far from where the fish was caught or farmed, and the majority of salmon fillets they buy are fresh and shipped by air, which is the world’s most carbon-intensive form of travel. Flying fillets from Alaska, British Columbia, Norway, Scotland or Chile so that 24 hours later they can be served “fresh” in New York adds an enormous climate burden, one that swamps the potential benefits of organic farming or sustainable fishing.

According to the NYT article and press release, at least, flash-frozen fish is not very distinguishable from fresh fish in terms of taste.  The main advantage of flash-frozen fish is that they can then be shipped the majority of the distance that they need to travel in container ships — the transport that is most eco-friendly for salmon — and hopefully avoid air travel altogether.

Of course, just because you’re buying frozen doesn’t mean you can’t worry about other factors too, if you want to. But as the press release points out, it’s not so simple as looking for the organic label or seeing whether the fish were farmed or wild:

Impacts vary dramatically depending on what, where and how food is produced. For example, early results of the study found that growing salmon in land-based farms can increase total greenhouse gas emissions ten-fold over conventional farming depending on how and where the farming is conducted. Similarly, while organic farming of many crops offers benefits over conventional production, organic salmon production gives rise to impacts very similar to conventional farming due to the use of resource intensive fish meals and oils.

What’s frustrating is how hard (or impossible) it is to tell, as a consumer, what the impact of a certain cut of salmon is based on the information that you have in the store or restaurant.  I hope that evaluation and documentation of these factors get a lot better over time, but in the meantime, it’s good to know which factors have a really big impact, and which tend not to.

Here were a few tidbits that surprised me:

Driving to the store alone and then cooking alone at home has a big environmental impact. Going out to dinner more, or just eating more frequently with friends and family at home, has huge benefit.

I’m not sure I understand this… wouldn’t driving to go out to dinner be the same as driving to the store (assuming you’re eating alone in both cases)?  Why should prepping food for one be so wasteful?  Anyone have any insight into this?  (If not, I might write to the authors.)

Across the globe, what is used to feed salmon and the amounts of feeds used vary widely. As a result, impacts are very different. Norwegian salmon farming resulted in generally lower overall impacts while farmed salmon production in the UK resulted in the greatest impacts.

So, as well as buy frozen, buy Norwegian.  (This is not a serious recommendation; I have no idea how many areas they actually included in this comparison, and as they note, it depends a lot from farm to farm.)

Catching salmon in large nets as they school together has one tenth the impact of catching them in small numbers using baited hooks and lures.

Again, I wonder why this is.  I would think that catching them in nets would be more likely to catch other sea creatures as well, but maybe there are other factors at play.  And I have heard that various attempts to catch fish in better ways — particularly dolphin-safe tuna — can have unexpectedly disastrous results (I’ll cover the tuna issue later, if there’s interest).  But it’s not obvious to me why this should be a problem.

Anyway, interesting article, and I’ll be trying to buy frozen salmon more often now — and other seafood as well, since it seems like the reasoning (the relative eco impacts of various shipping methods) should apply pretty well to all seafood.