To feed a crowded planet, put more fish on your plate?

New evidence shows seafood from aquatic farming—aquaculture—can help feed the growing global population while substantially reducing one of the biggest environmental impacts of meat production: land use. And it could do so without requiring people to entirely abandon meat.

To satisfy the protein demands of an anticipated nearly 10 billion people by 2050, the United Nations’ Food and Agriculture Organization and researchers around the world estimate current animal production will need to grow by an average of 52 percent. Meeting this need without pushing the environment to the brink will be critical.

A new study finds that the amount of cropland required to support future protein needs with more farmed aquatic animals would be significantly smaller than if terrestrial livestock production met those needs. This research is the first land-use analysis of future food systems to focus on aquaculture—the world’s fastest-growing food sector—and helps reveal its potential role in conservation and food security. The findings appear in the Proceedings of the National Academy of Sciences.

“While aquaculture can add some pressure because—ultimately—it is a food production system, our study demonstrates the relative amount is minuscule compared to terrestrially farmed animals,” says lead author Halley Froehlich, a postdoctoral researcher at the University of California, Santa Barbara’s National Center for Ecological Analysis and Synthesis (NCEAS).

“Aquaculture is not going to be the main strain on future crop feed and land use. It is—and will likely continue to be—terrestrial livestock.”

Aquaculture production depends on a number of land-based crops for feed, positioning it uniquely at the interface of aquatic and terrestrial food systems. To understand its land-use implications, the researchers examined how much land would be required to grow the seven most common crops that feed both terrestrial livestock and farmed fish under three scenarios for the year 2050, synthesizing food production data from the FAO and other scientific sources.

The investigators compared a business-as-usual scenario in which terrestrial meat consumption continues to dominate seafood to two scenarios in which aquaculture meets the additional protein demands of the global population in 2050. They found that replacing the added terrestrial production with aquaculture instead could spare between 729 and 747 million land hectares globally; that’s an area twice the size of India, the world’s seventh biggest country.

These savings, which also consider the substitution of land required for livestock grazing, would occur whether future aquaculture growth is completely marine-based or a mix of marine and freshwater—the two aquaculture scenarios the investigators assessed to understand a range of possible futures.

Land savings would result because fish and other aquatic animals are extremely efficient at converting feed to biomass for human consumption. For example, a cow requires anywhere from six to 30-plus pounds of feed to gain one pound of biomass, while most farmed fish need just one to two pounds of feed to do the same. This efficiency translates into requiring much less cropland to grow feed for the fish that people eat.

These results highlight the role that food choices play in the future of biodiversity, the biggest threat to which is habitat lost to human land use. “The expansion of agriculture across the world is driving most species extinctions and the dramatic loss of ecosystems,” says coauthor Claire Runge, a research scientist at University of Tromsø – The Arctic University of Norway, who was a postdoctoral researcher at NCEAS when the research took place. “This is only going to increase into the future. Aquaculture offers one way to reduce some of this pressure on our natural landscapes, wild places and wildlife.”

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