If middle-class Americans can afford salmon in 20 years, they might get it through a process like this:

The salmon hatch in nurseries. Eventually they are transferred to open tanks. The fish spend their entire lives in enormous indoor tanks, brushing against the same water, which has been recycled again and again. Waste is used to keep the water nutrient-rich. Eventually they are harvested. The salmon have never seen an open river, nor, perhaps, the sun—they have spent their lives in warehouses hundreds of miles from the sea.

From those landlocked warehouses—there’s already one in West Virginia—their bodies travel to restaurants and cities and grocery stores and homes.

This process may sound unnatural, but it increasingly appears to be the most sustainable way to raise salmon. So announced the Monterey Bay Aquarium Seafood Watch—the definitive source on the the sustainability of aquaculture—earlier this fall.

“Atlantic salmon farmed in recirculating aquaculture systems is a ‘Best Choice’ for consumers,” says the aquarium’s website. “These on-land production systems separate the fish from the surrounding environment and the risk of environmental impacts from pollution, escapes, and diseases are all low.”