All foods we eat have a climate impact. But when it comes to those impacts, not all foods are created equal. From plants and grains to dairy and meat, the effects our diets have on global greenhouse gas emissions depend on the types of food we consume, and seafood may be part of the answer to a more climate friendly diet.

A recent New York Times interactive illustrates that food and climate change are inherently linked, with food accounting for one-fourth of all global greenhouse gas emissions. Animal products such as meat and dairy, for example, are associated with far higher emissions than plant products. But certain seafoods rank below meat and dairy in terms of their emissions.

“Some sources of fish protein from the ocean actually have lower carbon footprints than sources of protein from land,” says Christopher Free, a sustainable fisheries scientist at the University of California, Santa Barbara.

While sustainable seafood is a well-established concept, climate conscious consumerism adds another level to our food choices.

“I think that ‘sustainable’ is a really loose, floofy word that tends to not carry a lot of meaning or specificity. Whereas climate change-centered seafood is more directed,” says Mary Parks, data management consultant at Red’s Best, a Boston-based seafood collaboration, and executive director of the Green Crab R&D Project.

So what exactly is climate friendly seafood? And how can climate conscious consumers select these seafood choices?

The ‘where’ and ‘how’ of fishing both matter

Seafood’s carbon footprint is primarily affected by fuel consumption. Free points to the reality that a large boat traveling the high seas to catch a migratory species like tuna is going to burn a lot more fuel than a small boat traveling less distance to catch a local species. “You know, if these boats got to go further from port to catch the fish, well they’re going to burn more gas and create more emissions,” says Basil Freddura, executive chef at the Daily Catch, a Sicilian-style seafood restaurant chain.

Where the seafood is processed also can increase its carbon footprint. Even if caught without much travel, shipping seafood for foreign processing and then importing it for sale can skyrocket fuel and energy consumption, leading to higher emission rates, Freddura says.

The tools used to catch seafood can also have variable climate impacts. So another element in categorizing a seafood as climate friendly involves how it was caught, Parks says. For example, purse seines – large nets that can be drawn closed, like a bag – have among the smallest carbon footprints of capture methods.

Picking domestically or locally caught and processed seafood can be one of the best ways to combat the high fuel consumption resulting from foreign catch and processing. Freddura says the squid he frequently cooks in his restaurant is both caught and processed in the Boston area to help minimize its carbon footprint.

Selecting seafood based on the tool it was caught with is also a good way to ensure a more climate friendly choice. Free says that small, lower trophic, pelagic species (those at the near bottom of the food chain) like anchovies, herring, and sardines have much lower carbon footprints, and these species are typically caught using purse seine nets. Parks adds that other methods, such as manually digging out clams for harvest, also have very low impact emissions.

The growing role of aquaculture

As fish farming increases in prevalence and importance, so too do its climate impacts. In 2018, researchers reported that crustacean farming leads to higher carbon emissions than the production of pork and cheese. Other types of aquaculture, such as catfish and tilapia farming, emit just as much greenhouse gasses as beef production. In contrast, multitrophic aquaculture, seafood farming that involves multiple levels of the food chain, can be far more climate friendly. Parks says multitrophic bivalve aquaculture, like oyster and mussel farming, can actually help combat climate change because it also grows kelp.

“You have your strings of mussels that are growing alongside your strings of kelp. Not only does it help in terms of [ocean] acidification, but it provides a little bit of a carbon sink and sequesters some of the local carbon, tempers the surrounding acidity, and also just overall produces a better shellfish product,” Parks says. The kelp create oxygen pockets which the bivalves thrive in, but also draw out some of the excess carbon in the ocean, which helps mitigate the effects of climate change.

More climate friendly means more seafood friendly

Climate friendly seafood and fishery stock health can go hand-in-hand, as climate impacts have increased the vulnerability of many fisheries. Those elements threatening fishery stocks, like overfishing, are only amplified by climate change. In a 2019 report, Free and his research team explain that overfishing can affect reproduction rates and also the diversity within and between species, both which tend to increase the vulnerability of fishery stocks to climate change’s effects.

“It kind of presents this one-two-punch, where rebuilding overfished populations is challenged by climate change and climate change could be contributing to overfishing as well,” Free says.

Expanding dietary choices into climate friendly seafood, then, could also mean expanding consumers’ culinary pallets to help take pressure off overfished stocks. Underutilized and/or invasive species typically tend to be more climate friendly than those seafoods most often consumed, like cod or haddock. In the Northeast, for instance, monkfish, dogfish, and green crabs are all good examples of underutilized or invasive species that fit this definition of climate friendly.

“In the face of climate change, a lot of these [invasive] species are going to do a lot better, actually, than a lot of the species that already exist in these environments,” Parks says. “Partially because they have no predators, but species like green crabs are actually hybridized to become more climatologically tolerant.”

Consumer responsibilities? Yes. A pass for industry? No.

But climate friendly seafood isn’t just an individual, consumer responsibility. “There are very strong debates,” says Xavier Irz, food markets scientist at the Natural Resources Institute, Finland, who explains that some view consumerism as an excuse for industry inaction.

“But I think that’s overly pessimistic. By making people a lot more aware about the impacts of their consumption, you are also creating a demand for new types of products. And I think that this will lead to innovation. And this, in my opinion, is going to lead to reactions throughout the supply chain.”

Free says his new lab has found that high-seas fishing with larger carbon footprints also tends to be unprofitable without government subsidies. “A lot of these high-carbon footprint activities are actually not profitable for the companies. I think often times consumer and business interests can be sort of well aligned.”

For consumers, Seafood Watch, FishWatch, and the Marine Stewardship Council are among the resources that offer reliable geographic, catch method, and stock health information that could also be used to determine how climate friendly a choice is. Additionally, the Seafood Carbon Emissions Tool explains and compares the carbon footprints of different fisheries to further help guide climate friendly choices.

Making sound diet decisions in a warming world all begins with more informed consumers.

“It’s starting to ask these questions,” Parks says. “Even though that might sound kind of daunting to the average consumer, to be like ‘Oh I need to have all these data points to make an informed decision,’ it is just even starting.”

AUTHOR

Rishya Narayanan is a graduate research assistant with the Global Resilience Institute at Northeastern University in Boston, Ma.