Eating Plants & Seafood

A paper we wrote about yesterday, Hilborn et al. 2018, went out with a press release that argued that a selective diet of seafood could have a lower environmental impact than a vegetarian or vegan diet. This claim comes from comparing the results of Hilborn et al with Poore and Nemecek 2018, a paper published just a few weeks before the Hilborn paper that used the same kind of analysis to also evaluate the environmental cost of food.

Both papers used a newer kind of analysis, called life cycle assessment, that can quantify nearly every environmental impact of a food product throughout all stages, from “cradle to grave.” Life cycle assessments are a comprehensive way to measure and compare the environmental impacts of food.

Poore and Nemecek compiled the most complete dataset of life cycle assessments for agricultural food production and reported general findings for several major food types. Hilborn et al. focused only on animal-protein, but went into greater detail. For example, Poore and Nemecek reported the impact of all capture fisheries grouped together, while Hilborn et al, reported the impact of different kinds of capture fisheries, like small pelagics, large pelagics, and white fish.

The results from Hilborn et al’s analysis show that certain kinds of seafood have a lower environmental impact than plants. For example, farmed oysters and small pelagic fish (like sardines) are probably the best food you can eat for the planet. Below is an unpublished figure provided by Ray Hilborn that adds plants to the comparison from Figure 1 in Hilborn et al. The figure, and discussion of plant-based food vs animal-based food, were cut during the review process.

(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, plants in green, 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.

So yes, a selective diet that includes seafood could have a lower environmental impact than a strictly vegetarian or vegan diet. Conscious eating can and should include several different kinds of food. Eat lots of vegetables & fruit, most seafood, some chicken or pork, and little red meat. A plant-based diet has lower impact relative to a standard diet that includes lots of animal protein, but a diet that includes fish can have as low, or even lower impact. Going vegan or vegetarian for the planet is commendable, but not necessary to lessen your dietary impact. Replacing red meat with fish is a simple and easy way to significantly reduce your environmental footprint.

The environmental cost of food and conscious eating is complicated. Papers like Hilborn et al. 2018 and Poore and Nemecek 2018 empower consumers to make better choices and should hopefully drive public policy changes to account for the environmental impact of food.

However, one thing missing from these analyses is the impact of biodiversity loss. Not every fishery is sustainable (though most are), but terrestrial agriculture is the largest driver of biodiversity loss since the last asteroid.

Read more about seafood’s role in global food systems and a more generalized look at the environmental cost of food in our Sustainable Seafood 101 series.

Max Mossler

Max Mossler

Max is an expert in environmental perception & policy. He is the managing editor at Sustainable Fisheries UW.


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