The science of sustainable seafood, explained

What is the Environmental Impact of our Food?

“Eating Right Can Save the World”
by Tim Zimmerman, Outside Magazine, January 7th, 2016

“The endless cascade of nutritional information—about localism, vegetarianism, veganism, organic food, the environmental impact of eating meat, poultry, or fish, and more—makes the simple goal of a healthy, sustainable diet seem hopelessly complex. We talked to scientists, chefs, and farmers to get the ultimate rundown on how you should fuel up.”

Author Tim Zimmerman’s discussion of this topic focuses primarily on carbon footprint of different foods. When it comes to seafood, he cites Dalhousie University professor, Peter Tyedmers, who argues, “when it comes to nitrogen and phosphorous, greenhouse gases, and other global-scale phenomena, absolutely most seafood is much better than most terrestrial animal production.”

But seafood sustainability certifications like Monterray Bay Aquarium’s Seafood Watch do not calculate emissions into their ratings. For example, some pot-caught species that are considered a “Best Choice” or “Good Alternative” by Seafood Watch standards might actually have greater greenhouse gas emissions than beef because of the exhaustive extraction practicalities of this gear type.

Zimmerman recommends mussels, clams, forage fish that “aren’t caught by a trawler,” and Pollock from the, “reasonably managed” Alaskan Pollock fishery as the best choices for consumers looking to maximize Seafood Watch ratings and minimize carbon footprint. Aquaculture is more complicated because the more “sustainable” choices are typically from closed re-circulating systems that require more energy and water use than open net pens.

Comment by Ray Hilborn, University of Washington, @hilbornr

At last – a great article on the environmental impacts of our food choices. The material on fish is particularly good and relies on the acknowledged world expert Peter Tyedmers. In the past decade, environmental impacts of capture fisheries has been put under the microscope. A tour through high end grocery stores will show you labels about what fish are “sustainable,” but step over to the meat or vegetable counter and there is no sustainability labeling, just information such as “organic” or “GMO free.” The implication is that meat and vegetables are obviously sustainable, as farming has been practiced for thousands of years.

In his book, The Perfect Protein, Andy Sharpless, the CEO of the environmental non-profit, OCEANA points out that fish are caught without fertilizer, pesticides, antibiotics or freshwater. Combine that with the generally low carbon footprint of most fisheries compared to the protein alternatives, and you have “The Perfect Protein.”

Another issue that has had great publicity in fisheries is biodiversity impacts, often through by-catch of non-target species. Species like sharks, turtles, marine birds and mammals are caught in some kinds of fishing gear. While such by-catch can often be largely eliminated by good fishing practices, there is no denying that fishing impacts biodiversity. But again we see agriculture and livestock getting an almost clean bill of health. This ignores the fact that agriculture transforms land dramatically: in most farmed areas the native large animals are essentially gone. While it is hard to compare the oceans directly, they have seen far less loss of biodiversity than farmed areas.

Zimmerman and Outside Magazine provide an excellent and much needed perspective on most of these issues; lets hope that it is the start of a rational conversation on the environmental impacts of what we eat.

Ray Hilborn is a Professor in the School of Aquatic and Fishery Sciences at the University of Washington. Find him on twitter here: @hilbornr
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2 Responses

  1. Dearest fellow scientists,

    Please note that the following comment is very subjective statement – and not very scientific: “But again we see agriculture and livestock getting an almost clean bill of health.” Subjectively too, if you look at the work in the EU by many environmental NGOs and like minded farming associations – the reform of the Common Agricultural Policy has been a piece of legislation that we have invested our time and capacity and continue to do so in order to reform it (for the good of the environment). It is true that farmland birds are the most threatened group of birds in the EU (according to the EU 2015 Red list assessment).

    Now, this doesn’t stop us from also working on other topics and this includes seabirds, which are the second most threatened group of birds in the EU. Therefore, just like we work on fast declining common farmland birds, such as the Skylark, we do the same for seabirds, such as the Atlantic Puffin. Also, please keep in mind that saving the endangered Black Tailed Godwit will not bring back the critically endangered Balearic Shearwater. Therefore we try to work on several fronts.

    All the best,


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