A farmer works with her company's oyster beds in Virginia. (Matt McClain/The Washington Post)

In the glory days, Virginia pulled an impressive haul of oysters out of the Chesapeake Bay — more than 4 million bushels. But that was half a century ago. Over the decades that followed, the state’s harvest tumbled hard, bouncing toward the bottom, like profits in a nasty stock market plunge.

Now, at long last, the Virginia harvest is showing signs of a modest rebound after hitting an all-time low of 17,600 bushels in 1996. The most recent haul for the October 2012 to March 2013 season surpassed 405,000 bushels. It was the third straight increase, almost double the 2011-12 harvest, and the highest total in a quarter-century.

The growing Chesapeake Bay harvests in Virginia and Maryland are nowhere near the historic levels in the 1800s, or the middle of the last century. But the growth affirms the hopes of biologists in both states that the lowly bay oyster can manage a comeback.

Gov. Robert F. McDonnell took credit for Virginia’s better harvest. In a statement, he said the upswing is a result of his commitment to the oyster industry and the jobs it creates.

McDonnell said the $2 million his administration set aside in the current budget for oyster restoration “is the greatest appropriation for the sector in Virginia history.” It bought 1 billion oyster shells, the equivalent of 4,000 dump trucks, that were spread throughout the state’s rivers so that oyster larvae floating on the current could find a home and grow fat.

Chesapeake Bay oysters making a comeback

The latest harvest was “even better than I hoped,” McDonnell said. “Good management has allowed us to put Virginia’s exceptional oysters on dinner plates around the world, creating good jobs, and generating new revenue for our state.”

It helped that Virginia developed oyster farming well before McDonnell’s tenure, 100 years ago, a move that’s paying dividends now. Nearly two-thirds of the current harvest resulted from private aquaculture.

Virginia is bullish on aquaculture, leasing plots of riverbed or bay floor to oyster farmers for $1.50 an acre. About 100,000 acres of the state water bottom is leased for farming. Although the practice is a century old, large-scale farming, which has been going on for about a decade, provided a significant boost to oyster growth.

In 2012-13, aquaculture yielded 257,000 bushels, a portion of which were created in a lab at the Virginia Institute of Marine Science. The triploid oyster, as it is called, is bred to be sterile and planted by farmers.

It grows faster, contains more meat, and is more resistant to a tag team of lethal diseases called dermo and MSX. The diseases, caused by microscopic organisms whose origins are unknown, kill many oysters about the time they become adults, just before they’re ready to mate, officials said.

In addition to disease, watermen grabbed too many wild oysters in public waters for years, depleting the stock. Virginia now guards its oysters with 300 acres of sanctuaries in public waters such as the Rappahannock, James and Great Wicomico rivers, allowing watermen to harvest them on a rotating basis about every two years, said John Bull, a spokesman for the state’s Marine Resources Commission.

Maryland has an even stronger lock on its oysters. The state forbids oyster harvesting on a quarter of its reefs, protecting them with a fine of up to $25,000 and 15 years in prison. The state posted a wild oyster harvest of 340,000 bushels for the season that ended in March.

“It’s nearly triple the previous season,” said Michael Naylor, shellfish program director for the Maryland Department of Natural Resources. The state had a “really good spat set,” he said, referring to baby oysters born and fertilized in the wild in 2010, and good water flow. The babies found shells to settle on and grew over two years.

Wild oysters have fared better in Maryland than Virginia. When Virginia’s wild harvest fell to about 1,800 bushels in 2001, Maryland had 348,000. But drought and disease in Maryland decimated the bivalve for several years starting in 1999 and dropped the harvest to 2,600 bushels in 2005, prompting a more aggressive restoration effort.

But overall, Maryland harvests fewer farmed oysters than Virginia because the state is only beginning to develop aquaculture. Lawmakers passed a law to allow oyster farming in 2009, and the amount of leased water bottom and harvest is not significant compared with Virginia’s, Naylor said.

Some biologists say the slow uptick in the harvest in both states is hardly enough to save the oyster. A 2011 study, which focused only on Maryland, recommended a drastic step: Halt oyster harvesting entirely in the state.

The study by the University of Maryland Center for Environmental Science said nearly 100 percent of the original oyster population has been lost since its peak in the early 1800s, and more than 90 percent has been lost since 1980. The figures for the decline are based on the oyster population in 2009.

“The magnitude of the decline raises concerns about potential for continued loss of natural oyster beds throughout much of Maryland waters,” the study’s chief researcher, Michael J. Wilberg, said at the time. “We recommend a moratorium on fishing until reefs and self-sustaining populations are restored.”