The salmon on your plate has a troubling cost. These farms offer hope.

AUBURN, N.Y. – A revolution in the way Americans eat salmon is quietly being fomented inside a former factory building on the industrial edges of Auburn, a small city in the Finger Lakes region of New York.

At LocalCoho, one of the country’s few sustainable salmon farms, 50,000 silvery coho salmon glide through concrete tanks filled with freshwater that recirculates through biofilters every half-hour. To mimic a marine environment, the lights are kept a dim, deep aqua blue that makes the salmon seem to glow.

In this eerie twilight, Andre Bravo, the chief operating officer, has carefully tended these fish since they first arrived, as a mound of glistening orange roe large enough to top 1,000 blini if they hadn’t been destined for piscine adulthood. It takes them 18 months to reach full size – about 6½ pounds – at which point they can be sold to high-end restaurants and retailers such as FreshDirect, where fillets sell for about $17 a pound.

That LocalCoho is able to raise these complex creatures on land is a radical change, one poised to turn an industry rife with environmental concerns on its head.

Salmon is the second-most-popular seafood in the United States, where the average American consumes more than 3 pounds a year. (Shrimp is No. 1, with average annual consumption reaching nearly 6 pounds in 2021.)

About 10% to 20% of this is wild Pacific salmon, most of which comes from well-managed fisheries in Alaska. But the rest is imported farmed fish raised in open net-pens in the ocean, a much-criticized system made even more problematic by rising water temperatures and other climate challenges.

Now, several land-based farms across the country are beginning to offer a more climate-stable alternative to traditional salmon aquaculture – one that’s cleaner, more ecologically responsible and potentially has a lower carbon footprint.

So far, their fish is available only in local markets, most of them in Florida, New York and Wisconsin. But experts say that land-based farming is the future of salmon aquaculture in America – and the world, as similar businesses gain footing in countries such as Denmark, Norway, Switzerland, Poland and Japan.

In the next two decades, they say, land-raised fish will become a significant part of America’s salmon supply. Worldwide, the field is drawing investments from companies involved in ocean farming, including the industry giants Grieg Seafood and Mitsubishi (which owns Cermaq Global, a company that has salmon farms in Norway, Chile and Canada).

About 99% of the world’s salmon farming takes place in open net-pens, which allow water to flow between farms and the marine environment. This free exchange has been at the heart of many of the industry’s issues, worsened by severe crowding that pollutes the surrounding ecosystem with excrement and other effluvia, and promotes the spread of diseases and pests like sea lice, resulting in the need for antibiotics and pesticides.

In the 2022 book “Salmon Wars: The Dark Underbelly of Your Favorite Fish,” Douglas Frantz and Catherine Collins compare this kind of aquaculture to factory farming.

“Most salmon farms are like floating feedlots,” Collins said.

The system is also susceptible to large-scale escapes, she said, which can wreak havoc on the fragile population of wild fish.

The 2017 escape of at least 250,000 fish from a Cooke Aquaculture farm in Puget Sound led Washington state to join California and Oregon in banning ocean-based aquaculture of nonnative species, like Atlantic salmon. And this past August in Iceland, a Norwegian-owned farm lost thousands of Atlantic salmon, whose escape carries the added threat that the farmed fish will interbreed with the endangered local wild Atlantic salmon. Studies have shown that the spawn of interbred fish have a compromised ability to survive in the wild.

“Every place where Atlantic salmon is raised in net-pens, the wild population has declined by as much as 70%,” Collins said.

Because of warming ocean temperatures, the number of feasible sites to build new ocean-based salmon farms is decreasing; even though the industry wants to expand its open net-pen operations, there’s limited space to do so.

Another major concern is the industry’s carbon footprint. Because it’s most valuable when sold fresh, most of America’s farmed salmon, imported from Chile and Norway, is flown in. Only 2% is farmed domestically. (Wild Pacific salmon, which is flash-frozen and shipped by boat, has a much lower environmental cost.)

Brian Vinci, the director of the Conservation Fund’s Freshwater Institute, a nonprofit conservation program that works with the federal Department of Agriculture, said land-based farms were the most realistic way forward to increase food security and provide high-quality protein to Americans without increasing dependence on imported seafood.

A 2016 study he co-wrote compared the carbon emissions of Norwegian salmon raised in ocean net-pens and flown to the United States with that of land-raised salmon sold within 250 miles of production. The local salmon’s total carbon cost was less than half of the Norwegian import’s. This percentage shrinks even more when the energy-intensive recirculating aquaculture systems, or RAS, at the heart of these farms runs on a renewable energy source, such as hydropower – or perhaps one day, biogas made from fish feces.

But these farms face steep challenges to making a profit.

“You need to get everything 100% right to make money,” Vinci said, and that’s a tall order when new technology is involved.

Atlantic Sapphire, the nation’s largest land-based salmon farm, has been plagued with setbacks since it built its $250 million farm in Homestead, Florida, in 2017.

Despite this, the company, whose salmon is marketed under the brand Bluehouse and sold in Publix Super Markets, has managed to raise $120 million so far this year.

Damien Claire, the chief sales and marketing officer, estimates that Atlantic Sapphire will break even in 2024, with an expected harvest of 10,000 metric tons of salmon, assuming no new big problems arise. It plans to scale up to 220,000 metric tons within the next decade.

If this does come to pass, it will go a long way in meeting U.S. demand for farmed salmon: 500,000 to 700,000 metric tons per year.

Vinci believes this goal is very attainable. The federal government, he noted, has invested tens of millions of dollars in researching recirculating aquaculture systems.

“Land-based technology is already viable,” he said. “We are 25 to 30 years away from replacing 50 to 70% of our imported farmed salmon with domestically raised fish.”

Until then, what should salmon-loving cooks look for?

Paul Greenberg, the author of “Four Fish” and “American Catch,” said wild Pacific salmon caught in the United States is always a good bet – if someone could persuade Americans to buy more of it. Much of our wild catch is exported to Japan and Europe.

That’s because the Pacific salmon species available (king, coho, sockeye, pink and chum) are different from the Atlantic salmon that dominates the market. For the most part Pacific salmon is leaner, with a more intense flavor. “Farmed salmon is fattier and blander, which the American consumer prefers,” he said.

For the most environmentally responsible farmed salmon, the Monterey Bay Aquarium’s Seafood Watch recommends land-based, RAS-farmed salmon from the United States – like LocalCoho’s and Bluehouse, if you can find it – and farmed Chinook salmon from New Zealand (Ora King is one brand), which are rated green (“best choice”). Those rated yellow (“good alternatives”) include salmon from the Faeroe Islands and Maine.

As for farmed salmon from Chile and Norway, which make up the vast majority of what’s available, the results are mixed. About half of the salmon from those countries is on the red “avoid” list, and it can be almost impossible to figure out exactly what you’re getting at the fish market or supermarket.

Corbett Nash, a spokesperson for the Monterey Bay Aquarium, said to look for fish that have been certified by the Aquaculture Stewardship Council, which has standards comparable to Seafood Watch’s. He also suggests finding a fishmonger you trust and asking questions, no matter what you’re buying.

”When you ask,” Nash said, “you put pressure on your supplier to make good choices.”

Then again, if you really want to eat clearly responsible, sustainable seafood, you can turn to bivalves. “Mussels and scallops are delicious,” he said, “and Americans don’t eat enough of them.”

This article originally appeared in The New York Times.