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Comprehensive Animal Protein Study Compares Environmental Impacts

Food
A mussel farm in Primorsko, Bulgaria. Vasil Raev / CC BY 2.0

Scientists behind a study published less than two weeks ago said that avoiding meat and dairy is probably the single best consumer choice you can make for the environment.

But if you want to watch your footprint while still eating meat, a study published Monday, which authors say is the most comprehensive comparison of the environmental impact of various animal proteins, has you covered.


The study, published in Frontiers in Ecology and the Environment, compared farmed livestock, farmed fish and wild-caught fish and found that livestock and farmed catfish took the greatest toll on the earth, while farmed mollusks and wild-caught fish caused the least damage.

"From the consumer's standpoint, choice matters," lead author and University of Washington (UW) School of Aquatic and Fishery Sciences professor Ray Hilborn said in a UW press release published by Phys.org. "If you're an environmentalist, what you eat makes a difference. We found there are obvious good choices, and really obvious bad choices."

But Hilborn said the study wasn't only useful for guiding consumers. It could also help governments in charge of free trade agreements and agricultural or environmental policy.

"I think this is one of the most important things I've ever done," Hilborn said. "Policymakers need to be able to say, 'There are certain food production types we need to encourage, and others we should discourage.'"

Researchers looked at 148 assessments of the environmental impacts of different animal proteins along all stages of production, comparing each product's energy use, greenhouse gas emissions, nutrient pollution potential and acid-rain-causing emissions.

The animal proteins that had the least impact on all four criteria were farmed mollusks like oysters, mussels and scallops and wild-caught sardines, mackerel and herring. Wild-caught pollock, hake and cod as well as farmed salmon also had a relatively low impact.

Unsurprisingly, farmed livestock had a high impact, with beef emitting about 20 times more greenhouse gases than farmed mollusks, chicken and salmon or some wild-caught fish.

However, farmed fish like catfish, shrimp and tilapia required more energy than most livestock because the water they live in has to be constantly circulated using electricity. Farmed catfish had greenhouse gas emissions about equal those of beef.

Farmed mollusks actually had environmental benefits because they absorb the excess nutrients that are often the result of other types of agriculture. The study also found that a diet that included low-impact farmed and wild-caught fish was actually better for the environment than an all vegetarian and vegan diet.

The study did not assess the impact of animal protein production on biodiversity, however, which researchers say they would like to tackle next.

As of 2016, nearly 90 percent of fish stocks were either overfished or fished to capacity, so examining the impact of various fishing practices on biodiversity would be especially important for assessing their true ecological cost.

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