Want a Lower Carbon Footprint? Pick Foods Without Feet

Where can we find nutritious, high-protein foods that are produced with relatively low greenhouse gas emissions? Take a look under the sea.


Finding foods that are both nutritious and have a low climate impact is difficult — especially foods high in protein. However, a recent study out of Dalhousie University’s School for Resource and Environmental Studies has illustrated that some seafood species are not only a valuable source of protein, vitamins, minerals, and fatty acids, but also have a relatively low environmental impact.

The main objective of the study was to analyze the amount of greenhouse gas emissions released during the production of globally imported seafood species relative to their nutrient densities. The study also aimed to assess the differences in these outcomes compared to land-based animal protein sources.

This work was led by researchers from the Research Institutes of Sweden, Dalhousie, and the Aquaculture Stewardship Council in the Netherlands and was published in Communications Earth & Environment, using data from global fisheries and aquaculture production.

The researchers found that wild-caught pink and sockeye salmon, small pelagic species (e.g. herrings), and farmed bivalves (e.g., oysters) had the smallest climate impact relative to their nutrient density. On the other hand, crustaceans (e.g., shrimp) and cephalopods (e.g., squid) emitted the most greenhouse gases and had the lowest nutrient density among the seafood species.

In comparison to land-based animals, 50% of seafood species emitted fewer greenhouse gases and had higher nutrient densities. In particular, the greenhouse gas emissions of beef were beyond the scale created, at 56 kilograms CO2 equivalent per kilogram of edible product, compared to the average seafood which emitted around 5 kilograms.

Pork and chicken, on the other hand, had similar CO2 emission levels to seafood during their production. The only seafood species that had a lower nutrient density compared to the land-based animals were some whitefish and Japanese carpet shells.

Across all of the seafood species that were assessed, vitamin B12, niacin, and vitamin D made the highest contributions to the nutrient density. These are all micro-nutrients that are very important for our physical and mental health.

These findings illustrate that many seafood species are both highly nutritious and have a low environmental impact, especially compared to land-based protein sources like red meat.

Based on the evidence, the researchers suggest that there should be emphasis on increased seafood consumption, especially small pelagic species, wild-caught salmons, and bivalves. This would hopefully decrease the amount of greenhouse gas emissions created by the seafood industry while still allowing us to reap the nutritious benefits of these species.

Nonetheless, there are still many aspects of the seafood industry that could be improved upon to minimize climate emissions further. For example, increasing the amount of seafood caught during each fishing trip would decrease the amount of fuel used by fishing vessels as well as the amount of carbon emitted.

All in all, as this recent study showed, there are specific seafood species that are meeting the sustainable, high-protein, and nutritious targets that are hard to find in other foods. Maybe a pescatarian diet shift is what the population needs — this would not only keep ourselves healthy, but our planet healthy too!

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Alexandria (Alex) Samson is a PhD student in the Department of Psychology at the University of Toronto. She completed her BSc in Neuroscience from Dalhousie University. Alex is a strong believer in open science and is passionate about making scientific research accessible to all audiences.