Air-shipped frozen seafood from sustainable fisheries generates less global warming than red meat, fresh fish, or farmed fish; findings apply only to wild fish that’s frozen after harvest 05/25/2009
Folks who purchase frozen seafood shipped by air—such as our customers—are rightly concerned about the global-warming impact of their decision.
Now, the recently published results of two studies—and those of a third, seen in a sneak preview—should prove reassuring to folks who buy frozen, air-shipped fish.
Frozen wild fish found preferable to fresh
The story begins back in 2005, when we spoke with associate professor Peter Tyedmers, Ph.D., of Canada’s Dalhousie University.
At the time, he and his colleagues were just starting up comparative life-cycle assessments of the GHG emissions associated with production and shipping of wild salmon versus tho GHGs associated with industrial farmed salmon.
Life-cycle assessment or LCA is a well-established method for calculating the environmental impacts of a product, process, or service throughout its entire life cycle.
The LCAs in the new studies measured the “carbon footprint”—that is, the emissions of greenhouse gases—associated with fishing, fish farming, livestock, and agriculture.
The GHGs in question are carbon dioxide from fossil fuels—either burned for energy or used to make fertilizers and pesticides—and methane emitted by beef cattle and dairy cows.
To perform an LCA on seafood products, researchers calculated the tons of greenhouse gases a fishery or a fish farm emits to produce one ton of edible product.
This required painstaking calculation of the “carbon equivalents” released into the atmosphere by the production of fish feed, by fishing or farm-maintenance boats, and by all transportation and cold storage needed to get wild or farmed fish to consumers.
Dr. Tyedmers says that satisfying consumer demand for fresh, never-frozen fish is more damaging than any other global warming impact associated with seafood.
This issue is highlighted each summer, when Seattle retailers use overnight air to deliver Alaska’s Copper River king salmon to market and then continue to fly fresh fish daily to the Lower 48… an especially expensive, wasteful practice we’ve rejected.
“As a society, we’re hung up on fresh. You just might get better quality with frozen-at-sea products. And there are environmental benefits as well,” Tyedmers told Seafood Business last year (Wright J 2008).
He noted that air cargo is wild salmon’s top source of carbon inputs… which is why we offset the carbon emissions associated with shipping our frozen wild salmon and seafood to customers.
Four years ago, Dr. Tyedmers’ team set out to compare the varying GHG emissions associated with production and distribution of wild salmon and farmed salmon products.
We’ve been waiting for the results of this unprecedented study, which is a joint project of Dalhousie University, the Oregon-based non-profit Ecotrust and the Swedish Institute for Food and Biotechnology.
This month, the trade magazine Seafood Business featured an advance look at the U.S.-Canadian-Swedish team’s LCA findings about wild and farmed salmon, and with regard to the GHG emissions associated with production, cold storage, and transport of frozen fish vs. fresh fish.
Life-cycle assessment favors wild salmon over fresh and farmed fish
The Seafood Business article’s sneak peek at the U.S.-Canadian-Swedish group’s findings come in the form of quotes from Dr. Tyedmers and study co-leader Astrid Scholz, Ph.D., of Ecotrust.
Dr. Scholz is an acknowledged expert on life-cycle assessments, while Peter Tyedmers is an ecological economist who earned his Ph.D. for research comparing the eco- and energy-impacts of salmon fishing versus salmon farming.
In the article, Dr. Tyedmers cautioned against oversimplified answers to complex food-energy-warming issues.
But the research performed by him and his international colleagues—and by the engineers in Pittsburgh—produced findings that allow consumers to categorize protein sources by their eco-impacts.
To reduce fossil-fuel use—and resulting GHG-production—the findings reported by these two independent teams suggest some priorities when choosing protein:
- Favor plant protein (beans and other legumes) over animal sources.
- Favor fish, eggs, and poultry over cheese and red meat.
- Favor frozen fish over fresh.
- Favor wild salmon over farmed.
- “A frozen product that’s shipped is best and air-freighted fresh tends to be worst”. —Astrid Scholz, Ph.D.
- “One of the biggest factors that influence the amount of fuel we burn in catching them [wild fish] is their relative abundance. So seafood from well-managed fisheries exploiting reasonably robust populations will generally have a lower carbon intensity than would be the case if the population is depleted. This highlights a major potential upside for seafood in a carbon-constrained world.” —Peter Tyedmers, Ph.D.
Dr. Tyedmers points out that if stricter rules and enforcement allow the world’s depleted fisheries to recover, this would further reduce the already low GHG profile of seafood.
In contrast, as he told Seafood Business, little can be done to lower the GHG emissions associated with standard beef, other than abandoning grain-feeding, which makes supermarket steaks and burgers artificially cheaper than the healthier counterparts from grass-fed cattle.
Professor Tyedmers also notes that the GHG emission profile of farmed fish varies widely, according to how much fishmeal is used in the feed, versus grains and other plant foods, production of which generates much smaller GHG emissions.
He cited Scotland as a region where industrial salmon companies feed their fish a higher proportion of fishmeal than most.
This practice may give some Scottish farmed salmon a healthier fat profile than rivals farmed in Norway or Chile (i.e., higher in omega-3s and lower in pro-inflammatory omega-6 fats). But it also leads to increased GHG emissions and places strains on critical “forage” species like sardines, menhaden, and herring, which support other wild fish and the greater ocean eco-system.
In the course of researching this article, we came across the equally encouraging results of two other life-cycle assessments… one performed by engineers based at Pittsburgh’s Carnegie Mellon University, and another by researchers from Sweden and Argentina.
Related research reports favor fish over meat and frozen fish over fresh
Carnegie Mellon’s Christopher Weber and H. Scott Matthews have been studying the GHG emissions associated with foods shipped over distances, and ways to offset them.
When they looked deeply into the generally laudable local-food or “locavore” trend, they found that replacing a day’s worth of red meat-based calories with chicken, fish, eggs, or fruits and vegetables cuts greenhouse (GHG) emissions just as much as eating an all-local diet.
As they wrote, “Shifting less than one day per week's worth of calories from red meat and dairy products to chicken, fish, eggs, or a vegetable-based diet achieves more GHG reduction than buying all locally sourced food” (Weber CL, Matthews HS 2008).
They cite two reasons for this finding, which clearly favors fish and poultry over beef and pork:
- Red meat produces, on average, 150 percent more GHG emissions per pound of edible product, compared with chicken or fish.
- The production phase of a food product accounts for 83 percent of the average U.S. household’s food consumption carbon footprint, while transportation represents only 11 percent of life-cycle GHG emissions. Production of standard, grain-fed beef and pork is notorious for intensive fossil fuel use, which translates into high GHG emissions. (Grass-fed beef is better on both counts.)
They found fewer GHG emissions from shipping fish that was frozen at sea (or upon its landing onshore), compared with shipping of fresh, never-frozen fish.
Their findings are echoed by ones reported by a pair of researchers from Sweden and Argentina, who performed a life-cycle assessment (LCA) of food products commonly sold in Swedish supermarkets.
As they reported, “For protein-rich food, such as legumes, meat, fish, cheese, and eggs, the difference is a factor of 30 with the lowest emissions per kilogram for legumes, poultry, and eggs and the highest for beef, cheese, and pork” (Carlsson-Kanyama A, González AD 2009).
The Swedish-Argentine pair placed fish in the middle of the GHG emissions range, but found the least impact from sustainable, abundant wild fish like Alaskan salmon, as reflected in their ideal mix of protein choices:
“The most climate-efficient way to consume protein is to eat a mixture of cereals, legumes, and fish caught in a fuel-efficient way” (Carlsson-Kanyama A, González AD 2009).
Another point they made is especially gratifying, given our aforementioned support for a Pennsylvania dairy farm’s methane-to-energy project: “Large emissions for ruminants [cattle] are explained mainly by methane emissions from enteric fermentation” (Carlsson-Kanyama A, González AD 2009).
Of course, by “methane emissions from enteric fermentation,” they mean cow farts and belches... equally accurate terminology judged too vulgar for a scientific journal.
All things considered, air-shipped wild seafood produces more global warming than plant foods do.
But all of the three new life-cycle assessments suggest that frozen, air-shipped seafood is an environmentally responsible source of protein… on top of being an exceptionally healthful one.
- Carlsson-Kanyama A, González AD. Potential contributions of food consumption patterns to climate change. Am J Clin Nutr. 2009 May;89(5):1704S-1709S. Epub 2009 Apr 1.
- Duchene L. Carbon footprints revisited. May 2009. Seafood Business. Accessed at http://seafoodbusiness.com/
- Weber CL, Matthews HS. Food-miles and the relative climate impacts of food choices in the United States. Environ Sci Technol. 2008 May 15;42(10):3508-13.
- Wright J. Energy efficiency: Carbon emissions factor into sustainable seafood movement November 5, 2008. Seafood Business. Accessed at http://seafoodbusiness.com/