The science of sustainable seafood, explained

A closer look at the environmental costs of food

The relationship between food and environment is one of the most important conservation issues in the anthropocene. Currently, agriculture uses 38% of the world’s land and accounts for over 90% of freshwater use. Farming and food production has been, and continues to be, the largest driver of habitat and biodiversity loss on the planet.

But, not all foods have the same environmental cost. Comparing and quantifying environmental impacts of different foods is important to guide agricultural policy and empower consumer choice. A paper published today is the most comprehensive comparison of the environmental impacts of meat and fish production—its findings can better inform personal food choices and, hopefully, will help decision-makers devise better food policies that account for environmental cost. Lead author of the study, Ray Hilborn said, “I think this is one of the most important things I’ve ever done…Policymakers need to be able to say, ‘There are certain food production types we need to encourage, and others we should discourage.'”

Quantifying environmental costs of animal protein

The paper used 148 different life-cycle assessment papers (also known as “cradle-to-grave” analysis) to look at environmental impacts associated with every aspect of animal protein as food. Researchers quantified 4 different kinds of major environmental impacts caused by food production: (1) electricity/energy use; (2) greenhouse gas emissions; (3) potential for nutrient runoff—this causes most of the world’s water quality issues; (4) potential to cause air pollution.

By standardizing environmental impacts per 40g/protein produced researchers were able to compare different kinds of animal proteins. Basically, the paper answers the question: what are the environmental costs of producing a hamburger patty’s worth of protein from different animal sources?

Energy & Greenhouse Gasses
  • Overall, livestock production uses less energy than most forms of seafood aquaculture. Farmed catfish, shrimp and tilapia use the most energy, mainly because constant water circulation must be powered by electricity. Climate impacts depend on the source of electricity. A tilapia farm powered by solar energy will be much less impactful than one that gets its electricity from a fossil fuel power plant.
  • Catfish aquaculture and beef produce the most amount of greenhouse gases.
  • Best choices for low-carbon protein are: small capture fisheries (like anchovy, herring, or sardines); farmed mollusks— such as oysters, mussels and scallops; whitefish like pollock, cod and haddock; farmed salmon; and chicken.
  • For capture fisheries, fuel to power fishing boats is the biggest factor, but fuel use varies dramatically depending on the kind of fish being caught and the gear being used. For example, using a purse seine net to catch small schooling fish like herring and anchovy uses the least fuel, while, perhaps surprisingly, pot fisheries for lobster use a great deal of fuel and have the highest impact per 40g of protein produced. Dragging nets through water, known as trawling, is quite variable and the impact appears related to the abundance of fish. Healthy stocks take less fuel to capture.
Nutrient runoff & Air Pollution
  • In addition to using very little energy, mollusk aquaculture actually absorbs excess nutrients that are harmful to ecosystems. Farmed mollusks also produced the least amount of air pollution, with small capture fisheries and salmon aquaculture close behind.
  • Livestock beef production has many environmental issues. Manure washed away by rain is a major concern for healthy waterways. Also, because cows produce methane, they contribute to pollution that causes acid rain.
  • Capture fisheries scored best in nutrient runoff because no fertilizer is used.
An interesting takeaway:
  • When compared to other studies of vegetarian and vegan diets, a selective diet of aquaculture and wild capture fisheries can have a lower environmental impact than either of the plant-based diets.
(a) Energy used (MJ), (b) GHG emissions (CO2-eq), (c) eutrophication potential (PO4-eq), and (d) acidification potential (SO2-eq) associated with different production methods per 40-g protein produced. Aquaculture production methods are represented in red, livestock in yellow, and capture fisheries in blue. The thick horizontal line in the box represents the median impact; the box bounds the interquartile range (IQR); and the whiskers extend to include all data within 1.5 times the IQR. Numbers above each box represent the number of studies included in each product category. Y-axis spacing is in log-modulus scale, but the labels are not. From Hilborn et al. 2018
Radar plots comparing environmental impacts (a) between different food production methods, (b) within aquaculture production methods, (c) within livestock production methods, and (d) within capture fisheries across all four impact categories examined (energy demand [MJ], GHG emissions [CO2-eq], eutrophication potential [PO4-eq], and acidification potential [SO2-eq]). Solid lines represent median impacts across broad food production system categories (ie aquaculture, livestock, capture fisheries); dashed lines represent median impacts of product subcategories (eg salmon aquaculture). From Hilborn et al. 2018

Read the full study here.

The most control an individual has over their environmental impact on the planet is through diet. This study should help consumers make more informed choices. For a more generalized overview of dietary impacts and the role of fisheries, check out The Cost of Food, a post in our Sustainable Seafood 101 series.

Large-scale improvements and conservation action will come with policy change and political pressure, register to vote here.

Picture of Max Mossler

Max Mossler

Max is the managing editor at Sustainable Fisheries UW.

Editor’s note: This post generated a lot of online disucession. Read our follow up story that presents some unpublished figures here.

Share this story:


Subscribe to our newsletter:

Read more:

3 Responses

  1. Congratulations on this work. It is great to see some rational analysis to inform consumer choice. We need to understand the whole picture before we take a single, simplistic measure, such as “food miles” as a mechanism for consumer choice. I believe eating fresh local produce is fantastic, as it often tastes better. It is however not a valid measure of environmental sustainability. Keep up the good work!

Leave a Reply

Ray Hilborn's every-so-often newsletter

The best way to keep up with our stories.