After decades of overharvesting of oysters in the Chesapeake Bay and many fruitless efforts to replenish them, scientists have re-established a significant population of the shellfish along the Virginia shore.

Researchers from the Virginia Institute of Marine Science at the College of William & Mary say that large experimental reefs created five years ago are now home to more than 180 million native oysters. That is still a far cry from the late 1880s, when the bay held billions of the oysters, Crassostrea virginica, and watermen harvested about 25 million bushels annually. But more larvae have been settling on the new reefs every year, the researchers said.

The results, they added, suggest there is a potential for further restoration in the bay by creating additional reefs where harvesting is prohibited.

“What we need are thousands of acres of permanently restored sanctuary reefs to turn this situation we have with the oyster around,” said David M. Schulte, a doctoral student at the institute and an author of a paper published in Science last week that describes the work. The sanctuaries would aid the oyster harvest by helping to seed nearby areas, but the overall effort would benefit the bay in other ways, by helping to clean the water and providing more habitat for fish, crabs and other marine life.