The science of sustainable seafood, explained

Ethics, impact, and nutrition: A critical review of plant-based meat

Last November, Outside published “The New Wave of Fishless Fish is Here,” an article hyping new plant-based fish products. The author had previously sworn off canned tuna and was thrilled to make a plant-based tuna-less melt at home one day to avoid, “the environmental impacts of industrial fishing. Bluefin tuna, of course, went out the window long ago. Then it was Chilean sea bass, swordfish, and farmed salmon. Cod, gone. Shrimp, toast,” he explained.

Though some of those fish did have overexploited stocks at some point in the past 20 years, each species currently has at least one MSC or ASC certified fishery or are rated green or yellow by Seafood Watch. The article had other head-scratchers, like a major misinterpretation of bycatch data and, though it mentioned very legitimate and real concerns of forced labor in distant water fleets, it mistakenly associated anchovy, sardine and mackerel fisheries with slave labor.

This endorsement of plant-based seafood alternatives replayed the greatest hits of sustainable seafood misconceptions and myths on its way to a common conclusion: eating vegetables is better than eating meat, fish included. It’s hardly a new opinion, but it is one receiving a fresh coat of paint through the burgeoning plant-based meat (PBM) industry. For those who can’t, “open a can of tuna without imagining a trickle of blood oozing out,” PBMs are the saving grace to keep a clean conscious while enjoying a tuna melt. Vegetarians have espoused this sentiment for decades: meat is bad, and plants are good. Your dinner is either white or black, moral or immoral. If you just eat more vegetables, everything will be ok.

PBM brands have secured a market share in the US and abroad behind ardent anti-meat campaigns that play to this narrative. The massive carbon footprint associated with beef production has been well documented and is, irrefutably, a major contributor to climate change. Lessening global demand of beef, especially in the US, is an important carbon mitigation tool as the market for PBM products continues to increase.

Impossible Foods, the largest PBM company, dipped a toe into its “finless fish” efforts that purported to include an anchovy-flavored broth, but numerous other brands have jumped into the market with two feet. Good Catch, Ocean Hugger Foods, Prime Roots and New Wave Foods have burst onto the scene, along with Beyond Meat—Impossible Food’s largest competitor. BlueNalu, a company producing lab-grown fish cells, raised $60 million last year to build a new facility in San Diego, a city famous for its tuna fisheries and cannery history. Even seafood industry giant Bumble Bee tuna announced a partnership with Good Catch to help pre-pandemic slumping sales.

Unfortunately, the official language from the PBM brands, and those reporting on the industry, fail to distinguish between the high carbon footprint of beef, and the much lower footprint of chicken and pork. Even worse, the PBM brands have smeared wild and farmed seafood with the same bloody brush used to shame the beef industry. Press releases and brand information pages are laden with the same myths as the Outside article.

“With respect to the urgency of the environmental impact, fish are second to cows, followed by other animals,” said Pat Brown, CEO of Impossible Foods in 2019 to The New York Times. But comprehensive analyses comparing seafood to PBMs are missing. Impossible Foods commissioned a detailed life cycle assessment (LCA) in 2019 but did not include any analysis of seafood in that study, making Brown’s association between industrial beef and fisheries confusing.

In this post, I try to fill that gap by comparing beef, PBMs – specifically the new Impossible Burger 2.0 – and seafood, in terms of the three primary components used to advocate for a plant-based diet: reducing animal deaths, reducing greenhouse gas (GHG) emissions, and increasing nutritional values. I will use a few more colors than just black and white to paint a picture of the environmental and ethical costs of seafood in relation to PBMs.

Ethical Treatment of Animals

Reducing animal deaths and minimizing animal cruelty has long been the ethical foundation for many vegetarians. The narrative has evolved over time, adding nuance and consideration for a lexicon of humane practices that admonish some negative associations: free-range, hormone-free, cage-free. Labels that read “USDA Organic,” or “Animal Welfare Certified” are commonplace on packaging these days; but ultimately, a carrot does not mean murder in the way a steak does, and that difference is critical for PBM alternative companies to reach potential customers.

The same conflict is evident when comparing that carrot with a fillet of fish. However, both the steak and the carrot stick required arable land to be cleared and removed of native habitat while the wild fish fillet did not come with associated habitat degradation (assuming it was harvested responsibly and selectively). Even under the most considerate planning, an agricultural operation requires clearing trees, plowing fields, spraying chemicals, and a host of other maintenance and volume-maximizing activities that likely result in animal casualties. Bycatch can be attributed to some fisheries in the same way, but not selective fisheries, and in many cases bycatch species can be brought to market in some form, which is certainly not the case with incidental agricultural victims like voles, crows and other field creatures.

Mike Archer, professor of evolution of earth & life systems at the University of New South Wales, attempted to quantify the number of animal deaths associated with a typical vegetarian meal in 2011. His point of reference was Australia, which is important because 98% of Australian-raised cattle are done so on natural grasslands that require minimal, if any, degradation to the natural habitat resulting in zero additional animal deaths by plowing or clear-cutting. Under these conditions, Archer determined that on average, one cattle death produced 45kg of edible protein, so about 2.2 deaths required to produce 100kg of edible protein via Australian cattle.

The total deaths required to produce 100kg of usable plant protein in Australia was estimated to be 25 times higher. “Anyone who has sat on a ploughing tractor knows the predatory birds that follow you all day are not there because they have nothing better to do. Ploughing and harvesting kills small mammals, snakes, lizards and other animals in vast numbers. In addition, millions of mice are poisoned in grain storage facilities every year,” explained Archer.  Mice plague data averages showed that about 100 additional mice were killed per hectare per year. The result was an estimate of 55 sentient animal deaths for 100kg of usable plant protein, though these measurements were far from definitive. Note that cattle fed plant protein account for much higher total deaths per 100kg than those that are free range.

Accurately measuring the amount of animal deaths caused by agriculture is extremely difficult. Fischer & Lamey produced perhaps the most comprehensive set of analyses in 2003 when they calculated about 6 field deaths per acre in the US. Far less than Archer’s average, but even so, Fischer and Lamey believed, “traditional veganism could potentially be implicated in more animal deaths than a diet that contains free-range beef and other carefully chosen meats.”

Many types of seafood would classify as a “carefully chosen meat.” For example, low bycatch, wild capture hook and line fisheries, like California’s troll chinook salmon fishery, compare quite favorably in the same kg of protein per death comparison. With a 10 pound per fish estimate, and a conservative 65% yield of usable meat per fish, equals 6.5lbs (2.9kg) of usable protein per death, or about 22 deaths per 100kg of usable protein. Consider the same comparison for tuna, which range to hundreds of pounds per fish in the market, yielding even fewer deaths per 100kg of protein.

There are far more considerations to be made in a discussion of ethics in food systems. Many fisheries would compare unfavorably when measuring human rights violations. Distant water fishing fleets facilitate some of the worst cases of forced labor on earth, and the nature of those supply chains makes those atrocities extremely difficult to remedy. But the mission of reducing animal sentient deaths is very different. In that analysis, seafood compares very favorably to plants, as does free-range beef.

Carbon Footprint

Where beef is unquestionably the worst offender is GHG emissions. Reducing emissions is the most compelling case for a plant-based diet. PBM brands wisely market their products around this component more than any other factor. Impossible Foods touts a burger that uses 96% less land, 87% less water and produces 89% fewer GHG emissions than an equivalent beef burger. These percentages came from a thorough LCA conducted in 2019 by a third party to specifically compare Impossible Burger 2.0 to “a conventional industrial ground beef burger produced in the U.S.” 

The study determined dairy cows account for 22% of beef burgers in the US and was clear to keep its measurements domestically, because as already outlined by Archer, beef production in other parts of the world have varying impacts. For all metrics tested, Impossible Burgers were dramatically less impactful than beef burgers.

But compared to some seafoods, the results are much different.

For an appropriate comparison, take Hilborn et al. 2018, which measured GHG emissions per unit of protein production for livestock, fisheries and aquaculture. “GHG production per portion of protein was lowest for mollusk aquaculture and small pelagic fisheries, with salmon aquaculture, chicken production, and large pelagic and whitefish fisheries also emitting less than 1.0 kg CO2-eq per 40 g of protein.” Beef production produced 5.66kg/GHG per 40 g protein, which measured higher than nearly all seafood.

Plant based meat comparison table
Figure 1. GHG emissions for 40 grams of protein produced. GHG values represent the median for each category. (Hilborn et al. 2018; ImpossibleFoods.com). 0.032 was added to each seafood category as an average estimate of post-harvest GHG emissions. (Winther et al. 2020)

It should be noted that lobster, catfish and some prawn fisheries all ranked higher than beef production for GHG emissions, proving seafood is a diverse category for these measurements, as with ethical measurements.

Another important consideration is that Hilborn et al. did not include emissions associated with processing in their analysis. Impossible Burger 2.0 would have the advantage over seafood or meat in this measurement, assuming that the Impossible product is produced directly into the ground beef look-a-like form that is sold in stores. We can only assume there is no processing impact because it was not specifically explained in the 2019 LCA.

A fish on the other hand, would need to be frozen, filleted, canned, or handled in some way to change it from its raw form into its market form, adding more GHG emissions along the way. Depending on the species, catch location and final product, many variations with different emissions could be conceivable. A study published in 2020 measured post-harvest GHG emissions from 20 Norwegian seafood products ranging across a diversity of fishing methods and fleets. The average was 0.2kg of carbon dioxide per kilogram of product. Protein content for fish is typically around 20% (19.8% for Atlantic salmon according to the USDA), so converting this CO2 average into Figure 1., we added 0.032 to each seafood species’ GHG emissions.

By these measurements, the Impossible Burger 2.0, which reportedly produces 89% less GHG emissions than a beef burger, would produce 0.62kg/GHG per 40g protein. That is much better for the planet than a beef burger, similar to large pelagic species and farmed salmon, and worse than mollusks, whitefish and small pelagic species. Consider anchovies: anchovy harvest produces 31 times less GHG emissions than the Impossible Burger 2.0, demonstrating the minimal impact of species that feed naturally in the ocean and can be harvested with low fuel requirements.


Vegetarian diets are associated with healthy lifestyles in western society. According to Pilis et al., there is plenty of support for that association: a properly applied vegetarian diet can reduce body mass, improve one’s plasma lipid profile, decrease the incidence of high arterial blood pressure, cardiovascular disease, stroke, metabolic syndrome, arteriosclerosis, with the chance for improved insulin sensitivity and lower rates of diabetes and cancer. While some nutrient deficiencies are possible from a monotonous vegetarian diet, “it can be reasonably concluded that the beneficial effects of a vegetarian diet significantly, by far, outweigh the adverse ones.” Considering obesity rates in the US and the relationship with meat-based fast food diets, vegetarianism can be a remedy to many unhealthy tropes.

The dietary benefits of plant-based meat substitutes, however, are far from consensus. Whole Foods’ CEO John Mackey criticized PBMs in an interview with CNBC in 2019, describing them as “highly processed” foods. Whole Foods gave PBM brand Beyond Meat its first break into the national retail space in 2013 when it began selling vegan chicken strips, but Mackey distanced himself from such products, saying, “I don’t think eating highly processed foods is healthy. As for health, I will not endorse [PBMs], and that is about as big of criticism that I will do in public.” His sentiments have been echoed by some dietitians, who determined that PBMs should be consumed as a dietary substitute for meat, not a replacement for vegetables.

Compared with ground beef on standard nutritional metrics, the Impossible Burger 2.0 is very similar, but surprisingly has more saturated fat than red meat.

Adding seafood species to the comparison, the debate is over – seafood is more nutritious than PBMs. Figure 2 below doesn’t even take into account the unique benefits wild seafood brings in terms of selenium and omega 3 fatty acids.

Charts comparing plant based meat to other kinds of food. Total fat, calories, carbohydrates, and protein are compared.
Figure 2. A compariosn of calories, total fat, carbohydrates and protein between ground beef, Impossible Burger 2.0, and eight common seafood species. The Impossible Burger 2.0 also had 2 grams of saturated fat per one ounce, while only ground beef (1.5g), Atlantic salmon (0.67g) and tilapia (0.33g) registered any saturated fat at all from the other species. Ground beef for this comparison contained 15% fat. (FDA.gov; ImpossibleFoods.com; USDA 2018).

For the most part, PBM brands have avoided a direct nutrition comparison when promoting their products directly with beef. In its entire 2019 Impact Report, Impossible Foods presents no nutritional comparison with red meat, but vaguely alludes to a “healthier” lifestyle and diet, and “more nutritious” options than beef in a few instances.

Surprisingly, PBM brands focusing on seafood alternatives have been more vocal on nutritional comparisons with wild capture fisheries, despite the advantages to seafood depicted in Figure 2. Good Catch stated that, “plant foods provide a wealth of nutrients that help reduce the risk of disease,” in its frequently asked questions section under the heading “why eat plant-based?” Cole Orobetz, co-founder of PBM company Alpha Foods falsely claimed, “the plant-based fish products are a better-for-you alternative that won’t contain toxic metals like mercury, microplastics or other contaminants that could otherwise be in fish.” The science is clear: two recent major studies found the health benefits of eating seafood far outweigh the (incredibly unlikely) negatives.

Environmental impacts of nutrition

Adding a new element to this discourse is Dr. Zach Koehn, whose dissertation, “Fishing for nutrition – improving the connection between fisheries, the food system and public health,” is sure to advance seafood emissions and nutrition research. Part of Koehn’s analysis focused on evaluating environmental impacts of nutrient-rich food production across diverse capture and aquaculture seafoods compared to other animal-sourced and vegetable food groups. “As a broad food group, fish and shellfish are often considered a better alternative to other animal-sourced foods,” explained Koehn.

To better understand seafood species and individual fisheries for these metrics, Koehn created a nutrient richness index (basically a score of how nutritious a food is) and then linked information from corresponding LCA reviews to measure relative environmental impacts, including GHG emissions, between different species. This methodology was used to compare plants, terrestrial animal proteins, and marine animals, with a specific separation between different modes of seafood production and wild capture fisheries.

Koehn found that, “the lowest environmental impact and most nutrient rich foods were vegetable food groups like grains, tubers, roots, seeds, as well as small pelagic fish in wild capture production and bivalves in aquaculture production.”

The environmental impact of nutrients in different kinds of food. From Koehn
Figure 3. Greenhouse gas emissions relative to nutrient richness across major food groups. Note the y-axis is on a logarithmic scale. (Koehn 2020).

As indicated in the caption, it is important to read Figure 3 with the understanding that the y-axis is on a logarithmic scale, making the highest GHG emitting foods tested on the right side of the graph orders of magnitude more impactful than the slope of the data set suggests. It is not possible to estimate precisely where Impossible Burger 2.0, or any other PBM products might fall on this chart without more comprehensive data from Impossible Foods, but a fair estimate would assume PBMs would be near cephalopods and large pelagic species (roughly 10% of beef’s GHG relative to nutrient richness).

Towards a nuanced approached to plant-based meat

As stated in the introduction of this article, I do not want to diminish the positive impact PBMs can have on curbing GHG emissions and reducing the massive environmental footprint of the beef industry. Replacing beef with plant-based burgers is undoubtably good for the planet. In 2018 the average American consumed 222.2 pounds of red meat and poultry. That was more than 10 ounces of meat per day, which is more than double the amount recommended by FDA nutritionists.

There is no denying the incredible environmental cost to produce beef; it justifies a major change to our food system and creates a compelling and effective narrative for marketing PBMs. However, despite PBM companies picking on the seafood industry, most seafood production is not comparable to its red meat or poultry counterparts on the basis of sentient deaths and ethical treatment of animals, environmental degradation, and nutritional deficiency. To criticize wild capture fisheries with the same campaign used to demonize industrial ground beef is irresponsible and linked to no scientific data.

Unfortunately for ashamed tuna-melt enthusiasts like the Outside magazine writer, there is no such thing as a non-extractive food. Koehn’s analysis demonstrated this reality across animal proteins, land and sea, but also across plants. Plant production requires land use, water use, agricultural runoff, and therefore must be associated with varying degrees of opportunity costs that are rarely associated with responsibly managed wild capture fisheries. Those factors were not included in this post or analyzed by Koehn, but they are critical for a true measurement of wild seafood’s nutritional value compared to other foods.

Impossible Foods may have realized these considerations and quietly moved their fish-less seafood campaign to the back burner. At no point in the Impossible Foods comparative environmental LCA or in the company’s 2019 Impact Report was seafood mentioned. Curiously, almost no word of Impossible Food’s seafood replacement product line has been printed since 2019 when The New York Times described, “the fishless-fish project [as] part of Impossible’s grand ambitions to devise tasty replacements for every animal-based food on the market by 2035.”

Impossible Foods cannot effectively copy and paste the same marketing campaign and LCA used to shame the industrial beef industry onto any sector of the seafood industry. Brands like Good Catch, BlueNalu, Ocean Hugger Foods, Prime Roots specifically targeting seafood alternatives should focus their efforts on replacement products for higher impact seafood species like shrimp, catfish and tilapia rather than targeting tuna, bivalves, or salmon, which would not be compelling pursuits on the basis of environmental conservation.  

For any PBM advertising campaign, lumping all seafood together into any one measurement is unfair and misrepresentative. “As a category, ‘seafood’ represents a multitude of species and modes of production. It is important to consider not only the species but also both broad production system (i.e. capture fisheries or aquaculture) and the specific form of production (e.g., trawl, troll, trap gear types for capture fisheries) that yield specific products with particular nutrient compositions and environmental impacts,” explained Koehn.

Food systems are full of nuance and complicated considerations. Seafood is no exception. But as we have tried to convey, time and time again on SFUW, sustainable seafoods exist and they can be a solution to a myriad of social, environmental and nutritional issues. PBM brands and misguided journalists aspire to address these very same issues. If that is their true mission, then maybe they should be eating more anchovies, mussels, salmon and whitefish, and fewer Impossible Burgers.

Picture of Jack Cheney

Jack Cheney

Jack has sourced, sold, cooked, and sustainably certified seafood over the past 10 years. In addition to his contributions to Sustainable Fisheries UW, he is working to increase traceability into supply chains and educate consumers, chefs and retailers on the value of environmentally sustainable seafood. He earned a Master's in Marine Affairs from the University of Washington in 2015.

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