In 18 months to two years, the mesh bags of baby oysters recently scattered into Virginia's York River could yield hundreds of bushels of market-size oysters-and herald a new way of doing business. To reach that point, the 2 million spat planted in August will have to survive the forces that have depleted stocks of the briny catch in the Chesapeake Bay-disease, pollution and, more recently, cownose rays.

If they do, it could demonstrate whether aquaculture is a viable option for the oyster industry. "This is an alternative way to keep oystermen oystering and watermen on the water," said Tommy Leggett, an oyster specialist with the Chesapeake Bay Foundation.

As volunteers emptied the mesh sacks, Leggett maneuvered a foundation oyster boat, Chesapeake Gold, over a half-acre of river bottom 10 miles upriver from the Coleman Bridge.

The fingernail-size spat are the offspring of two strains of native oysters bred to withstand damage from disease-causing parasites Dermo and MSX. As another precaution, the spat were allowed to attach to 200 bushels of natural oyster shells while soaking in nursery tanks. The 3- 4-inch-long shells make it harder for the predatory rays to scoop up tasty young.

An expected yield would be 300 to 400 bushels of market-size oysters worth just enough to offset the $12,000 cost of the project, said Lake Cowart Jr., head of Cowart Seafood Corp., near Lottsburg.

Cowart, who supplied a portion of his leased oyster grounds to grow the oysters, is a partner in the effort designed to advance aquaculture. The Bay Foundation and the Virginia Institute of Marine Science are the other principals in the state grant financed through the sale of Chesapeake Bay vehicle license plates.

Cowart said he believes the survival of Virginia's oyster industry depends on aquaculture techniques such as these. He is raising millions of sterile native oysters in Northern Neck waterways in floats that keep out rays and accelerate shellfish growth.

Millions of bushels of oysters used to be hauled from Virginia waters. Since the spread of disease, annual harvests have plunged more than 90 percent. The catch reached its lowest point of 22,949 bushels during the 2000-01 season and was about 50,000 in the 2006-07 season.

Leggett, who grows oysters and clams commercially in the York River, said he believes that the oysters and the oyster industry can be revived. The effort, he admitted, is hampered by pollution that makes the aquatic environment even more hostile to native oysters.

"We've just started tackling water-quality improvements the last few years,'' he said. "And we've only been working on oyster restoration the past 15 years."

"It's no wonder," he said, "that we haven't restored the oyster."