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.


  1. Marta Said,

    December 14, 2009 @ 4:34 pm

    That’s really awesome. I don’t eat fish (not for any environmental reasons, just ’cause I think it’s icky) but it makes me wonder what other things about food I’m getting “wrong.”

  2. Jade Said,

    December 14, 2009 @ 4:56 pm

    Yes I’ve heard the same thing about frozen fish vs “fresh” – but I’ve also heard that frozen fish is actually fresher because its flash frozen right away rather than lying around for a day or so.

    the other thing that often frustrates me about “eat organic and local foods!” is that I live in boston – we just don’t have much choice of organic local foods in the winter. Its a much harder thing for us to eat locally than californians who get harvests year round.

  3. Sarah Said,

    December 14, 2009 @ 6:03 pm

    I believe that it’s broadly true that shipping by container ship is the most environmentally friendly option for food, which has some surprising implications in the arena of canned food (which is frequently shipped this way). On the converse side, almost anything that travels by plane or refrigerated truck is a tough sell on the green front, even if it’s organic!

  4. cee Said,

    December 18, 2009 @ 8:18 pm

    If you’re listing factors of environmental impact, you might want to include pointers to one or more of the lists of more-vs-less sustainable seafood. I keep one in my backpack, though by now I know I’ll generally default to tilapia or mahimahi (which have the added virtue of being relatively cheap).

    And if you get into a tuna discussion, you might want to include how it’s now being fished down toward extinction, so however it’s caught, it’s not a good environmental choice.

  5. lauren Said,

    December 18, 2009 @ 10:57 pm

    @cee: yes, I plan to cover more info/resources like that soon. Do you have a favorite online list?

  6. Joe Decker Said,

    December 19, 2009 @ 1:08 pm

    I haven’t comparison shopped info on seafood sust. resources, but one that is very well-regarded are the various guides available through the Monterey Bay Aquarium’s Seafood Watch Program:

    They provide a variety of guides that attempt to give a green/yellow/red sort of overview of seafood choices based on geographic location within the US.

    I suspect there’s something valuable about the reductionist approach, it’s possible to carry one of their guides in a wallet, and to make quick choices even at restrauants based on incomplete information about seafood sourcing.

    Heck, there’s even an app for it: