Your choice in non-vegetarian matters

Turns out when it comes to the options of meat and seafood, the choice matters - Not just for your but for the environment as well.

According to a study conducted by the University of Washington, industrial beef production and farmed catfish are the most taxing on the environment, while small, wild-caught fish and farmed mollusks like oysters, mussels and scallops have the lowest environmental impact.

The study authors believed it is the most comprehensive look at the environmental impacts of different types of animal protein production.

"From the consumer's standpoint, choice matters," said lead author Ray Hilborn. "If you're an environmentalist, what you eat makes a difference. We found there are obviously good choices and really obvious bad choices."

The study is based on nearly a decade of analysis, in which the co-authors reviewed hundreds of published life-cycle assessments for various types of animal protein production.

Also called a 'cradle-to-grave' analysis, these assessments look at environmental impacts associated with all stages of a product's life.

Of the more than 300 such assessments that exist for animal food production, the authors selected 148 that was comprehensive and not considered too 'boutique', or specialized, to inform their new study.

As decisions are made about how food production expands through agricultural policies, trade agreements, and environmental regulations, the authors note a 'pressing need' for systematic comparisons of environmental costs across animal food types.

"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.'"

Broadly, the study uses four metrics as a way to compare environmental impacts across the many different types of animal food production, including farm-raised seafood (called aquaculture), livestock farming and seafood caught in the wild. The four measures are: energy use, greenhouse gas emissions, potential to contribute excess nutrients - such as fertilizer - to the environment, and the potential to emit substances that contribute to acid rain.

The researchers compared environmental impacts across food types by using a standard amount of 40 grams of protein - roughly the size of an average hamburger patty, and the daily recommended protein serving.

For example, they calculated how much greenhouse gas was produced per 40 grams of protein across all food types, where data were available.

"This method gives us a really consistent measurement people can relate to," Hilborn said.

The analysis showed clear winners that had low environmental impacts across all measures, including farmed shellfish and mollusks, and capture fisheries such as sardines, mackerel, and herring. Other capture fish choices with relatively low impact are whitefish like pollock, hake and the cod family.

Farmed salmon also performed well. But the study also illuminated striking differences across animal proteins, and the researchers advise that consumers must decide what environmental impacts are most important to them when selecting their food choices.

The study appears in the journal Frontiers in Ecology and the Environment.