Deep in the coalfields of southern West Virginia, in tanks filled with pure, cold water from under a long-shuttered mine, Atlantic salmon swim.

They start as tiny pink eggs with two black dots for eyes. They surge from fry to fingerling to full-grown in less than a year in a carefully controlled, disease-free environment where antibiotics, hormones and other contaminants are nonexistent. They are trucked out live, ending up on dinner plates up and down the East Coast.

That, at least, is Bill Martin’s vision.

Martin recently bought a West Virginia fish farm that once produced arctic char. After some upgrades, he’ll use it to raise salmon and steelhead trout in low-salinity water hundreds of miles from either species’ natural habitat.

Martin knows how it sounds: Eighty percent of the fresh and frozen salmon consumed in the U.S. comes from net pen farms in coastal waterways around the world, with Chile the single largest supplier.

But near the landlocked town of Man, he has found a recipe for success — a seemingly limitless supply of clean, cold water and a sprawling compound of buildings with fish tanks already in place. All within an easy day’s drive of millions of consumers.

Martin’s company, Blue Ridge Aquaculture Inc., ships 70,000 pounds of live tilapia every week from its farm in Martinsville, Va. It’s growing another saltwater species, cobia, at a farm in Saltville, Va., and hopes to expand into oysters, lobsters and more to feed Americans’ growing demand for heart-healthy seafood.

Inland fish and seafood farms are the future, he says.

“Net pens, they are dinosaurs. They’ve done a tremendous job against insurmountable odds for a long time, but there’s a better way now.”

Environmentalists have long battled net pen salmon farms, complaining that escapees weaken the gene pools of wild fish, spread disease that threaten wild populations and create cesspools of waste in waterways. Some, including the Washington, D.C.-based Pure Salmon Campaign and 1planet1ocean, now advocate land-based, closed-containment systems.

Carnivorous fish like salmon produce waste that falls through the nets and into the sea — a practice Don Staniford of the Pure Salmon Campaign says amounts to “freeloading on the marine environment and not paying for their pollution.”

Closed systems that treat and recirculate wastewater cost more to set up, but Staniford contends they’re more economical because less food is wasted, fish burn less energy and grow faster, and there is little chance of disease transfer.

Blue Ridge Aquaculture relies on technology developed by MariCal Inc. of Portland, Maine, that lets fish typically harvested from salty coastal environments grow in tanks fed by freshwater sources. MariCal discovered a way to control proteins called calcium receptors that allow fish to sense and respond to changes in salinity and nutrients.

David E. Guggenheim, who formed the 1planet1ocean conservation group, consults for Aquaculture Developments LLC of Pittsburgh, another firm bringing more closed-containment technology to the U.S.

Such farms are needed if seafood suppliers are to keep up with demand, he argues. And if more U.S. operations thrive, the technology will spread.

“And it only makes sense,” he says. “We’ve domesticated chickens and cows and pigs, but we’re still hunting wild animals in the ocean.”

Land-based farms will never replace water-based operations because some fish, including tuna, are too large to grow in tanks. But advocates say they could reduce reliance on offshore farms and relieve pressure on wild stocks.

The Seafood Choices Alliance says three-quarters of the world’s fisheries are being fished at or beyond capacity, and the health of the oceans is declining globally. Joey Ritchie Brookhart, a senior project manager in Monterey, Calif., says companies like Blue Ridge help address concerns about environmental sustainability.

“The question is whether it will work,” she says.

Not all conservation groups believe closed containment is proven technology, and not all land-based aquaculture is created equal.

Bivalves — mussels, clams, oysters and scallops — are raised “in a benign way,” Brookhart says, because they require no feed or chemicals.

In the middle of the sustainability spectrum are species that can thrive on plant life like tilapia, catfish and barramundi, a species native to Australia but now being raised in Massachusetts by Australis Aquaculture LLC.

Then there are meat eaters like salmon, which require protein to grow and produce the most waste.

Even if Blue Ridge is successful, Brookhart says it’s unlikely net pen operators will follow suit.

“They’ve been doing it that way for many, many decades,” she says, “and to tell them their operation is not sustainable and it should be done on land is going to create a lot of resistance.”

The Bush administration has been pushing ocean-based farms, too, with federally funded pilot projects studying the feasibility of raising mussels and fish in offshore farms from New Hampshire and Puerto Rico to Hawaii.

Sebastian Belle, executive director of the Maine Aquaculture Association, says either kind of farm can harm the environment when badly managed.

“As a guy who’s done both, I don’t believe that either technology is the silver bullet to the environmental issues,” he says.

Nor are net pen operators feeling threatened.

“It’s kind of a simple equation: 75 percent of the earth is covered by oceans,” Belle says. “I don’t think that anybody’s suggesting the emergence of land-based technology is going to stop development of ocean-based farming. The conditions for farming fish in the ocean are just too good, and there’s a lot of space there.”

There’s also a lot of demand. The U.S. imported 457 million pounds of fresh and frozen salmon in 2007, or $1.4 billion worth, according to the U.S. National Marine Fisheries Service.

Shifts in demographics and population will keep demand strong through 2020, says Howard M. Johnson, an Oregon-based seafood marketing and market research expert.

If Blue Ridge can duplicate its success with tilapia, he says, it can help fill a market need.

Per Heggelund, who raises Pacific salmon in a closed-containment system in Rochester, Wash., says there’s another potential market niche: all-natural, eco-farmed salmon.

Heggelund’s Domsea Farms began working with Whole Foods in 2000 to develop standards for salmon he raises entirely in freshwater. Stores in the Seattle area began selling it this month.

New York-based Environmental Defense formed a similar partnership with Wegmans Food Markets, collaborating on standards for eco-farmed shrimp.

“People pay more if they feel good about it,” Heggelund says.