The most nutritious and least polluting fish | Currently

According to a study that analyzed dozens of sea creatures eaten around the world, replacing meat with certain types of fish could help us reduce our carbon footprint without sacrificing nutrition.

The study was published September 8 in Communication Earth & Environment. According to the authors, farmed mussels (shellfish such as mussels, clams and oysters) and small fish that inhabit middle or surface areas (pelagic), such as anchovies, mackerel and herring, produce fewer greenhouse gas emissions. They are also more nutritious than beef, pork and chicken.

The goal of the research was “to better understand the climate impacts of eating marine fish and shellfish given their very different nutritional qualities,” explains Peter Tyedmers, an ecoeconomist at Dalhousie University in Halifax and co-author of the paper.

The results are consistent with previous studies, including those carried out by members of the Tyedmers group on fish and sea shells eaten in Sweden. This time they wanted to include a more diverse and global range.

Benefits of Eating Fish

Food production causes about a third of global greenhouse gas emissions, mainly methane and carbon dioxide. More than half of these emissions come from livestock. Plant-based diets offer a greener alternative to eating meat, but the benefits of eating fish and shellfish regularly are often overlooked, the study says.

The research used 41 species of fish and shellfish to create a nutrient density score that assessed essential nutrients such as certain fats and vitamins. Species studied included wild and farmed fish, crustaceans, bivalves, and cephalopods (the latter group includes squid and cuttlefish). The team used available emissions data for 34 of these species to compare their nutrient density (amount of nutrients per calorie) to the emissions associated with their production or capture.

Half of the marine species offered higher nutrient yields relative to emissions (see “The best fish to fry”). pink salmon (Oncorhynchus gorbuscha), sockeye salmon (Oncorhynchus nerka), wild-caught small pelagic fish and farmed mussels provided the most nutritious protein and produced the lowest emissions. The climate impact of some whitefish such as cod (Gadus sp.) was also low, but they are among the foods with the fewest nutrients per calorie. Wild-caught crustaceans produce the most emissions, with a carbon footprint comparable only to beef. The authors note that their GHG emissions data do not include post-production GHG emissions such as those from refrigeration or transport.

The analysis gives greater prominence to the role of marine fish and shellfish in food systems, says Zach Koehn, a marine scientist at the Stanford Center for Ocean Solutions. He adds that one barrier to increased consumption of these species is their availability and high price. If this is not fixed, many people may not be able to afford them.

Tyedmers admits having access to a varied diet is a privilege. “Every time fish is replaced by beef, that’s a small climate victory. It doesn’t have to be every meal,” he says.

Jude Coleman/Nature News

article Translated and adapted by Research and Science with permission from the Nature Research Group.

Reference: “Assessing the nutritional diversity of seafood together with climate impact informs more comprehensive nutritional advice”; Martha Bianchi et al. in Common Earth EnvironmentVol. 3, No. 188, September 8, 2022.

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