Large sections of several Maryland rivers would be set aside as permanent oyster sanctuaries under a new management strategy proposed by Maryland officials in December that is aimed at restoring native oyster populations and rebuilding income for watermen.

The source of that income would change: The plan promotes oyster aquaculture by opening 600,000 additional acres of Bay bottom to leasing, including 95,524 acres of natural bars that previously had been off-limits for leasing.

Wild oyster harvests can still take place, but areas available to the traditional fishery will be gradually decreased by the expanded sanctuaries and new leased areas, and it will be more tightly managed.

"If we are ever to achieve our goal for a revitalized oyster population we must act now, and science tells us that this is the best way to begin rebuilding a sustainable, robust population," said Maryland Gov. Martin O'Malley in unveiling the plan Dec. 3.

The plan follows key recommendations from recent reports about Bay oyster restoration, including those from a five-year oyster environmental review and the Maryland Oyster Advisory Commission, which emphasize setting aside large sanctuaries for restoration, protecting them from harvest and transitioning the commercial fishery to aquaculture.

The Bay's oyster population has been devastated by disease, overharvesting and water quality problems. But in the past, oysters have often been placed in the Bay in the name of restoration, then harvested, ultimately achieving neither ecological nor economic goals.

As a result, nearly two decades of oyster restoration efforts have had little impact-since 1994, the number of "quality" oyster bars in Maryland has decreased from 200,000 to 36,000 acres, according to state surveys.

For too long, O'Malley said, the state has been "literally chasing our own tail" by putting millions of oysters into the Bay to boost the population, only to have millions taken out.

The new plan would place 24 percent of the state's 36,000 acres of quality oyster bars in sanctuaries. A year ago, only 4 percent of those bars were protected, "and those were so small, as to be largely unenforceable," said Mike Naylor, who oversees the Maryland Department of Natural Resources' shellfish program.

It was often difficult to determine whether someone was fishing in, or out, of the small sanctuaries, creating a situation so bad that the state's 21-member Oyster Advisory Commission warned in a report this year that no oyster restoration effort would be successful until the DNR was able to halt the "rampant theft of oysters."

"It was recognized that having very small sanctuaries completely surrounded by public fishery, made enforcement extremely difficult," Naylor said. With large sanctuaries, it is more obvious if illegal fishing is taking place. The department also plans to bolster enforcement by tapping into surveillance systems used by the Department of Homeland Security that are located near some of the sanctuaries.

Larger sanctuaries also allow oysters in good production areas to reproduce, and still have some of their larvae, which generally float downstream, protected when they land. Over time, the hope is that the oysters that manage to survive several years of disease pressure will reproduce and pass that resistance onto their offspring.

At the same time, rebuilding populations in those areas may ultimately support wild harvests, as some larvae floats downstream out of the sanctuaries. "What we are trying to do in most areas is protect high concentrations of oysters in the headwaters of these rivers," Naylor said.

The proposed new sanctuaries are huge, including entire rivers such as the Little Choptank. Other proposed sanctuaries include the Magothy River, Chester River, the area between the mouths of the Patapsco and Back rivers bounded by the main channel, Upper St. Mary's River, Point Lookout, Upper Patuxent River, the mainstem portion and lower tributaries of the Choptank River and the area between the main channel and shore from Hooper Strait to Smith Island.

The plan emphasizes aquaculture, which historically has not been promoted in Maryland. But during its last session, the General Assembly passed legislation that called for opening more areas to aquaculture and streamlining the permit process. O'Malley said those actions could spur as many as 150 new aquaculture operations in the short-term.

Nearly 95 percent of the oysters harvested worldwide are grown in some form of aquaculture. Research funded by the National Oceanic and Atmospheric Administration's Chesapeake Bay Office in recent years showed that growing sterile native oysters in aquaculture can be economically viable in the Bay, and an increasing portion of the Virginia harvest comes from aquaculture.

Although fishery officials envision oyster production transitioning to aquaculture, a public fishery-valued at about $3.5 million annually-will remain and efforts will continue to maintain habitat on public oyster grounds. But management will change over time, Naylor said, with the state moving toward setting catch limits for specific geographic areas, and closing those areas when the limit is reached to better maintain the population.

"We're hoping that by opening more of the Bay's bottom open to aquaculture, and at the same time beginning to constrain the wild fishery somewhat, we will encourage people to start this transition, while they are still able to make a little money off the wild harvest," Naylor said.

While the area open to wild harvest will be reduced, 76 percent of the remaining high-quality bars will stay open under the DNR's plans.

Nonetheless, the plan raised worries among watermen, who will see some of their best oyster bars transformed into sanctuaries. Larry Simns, president of the Maryland Waterman's Association, said he was first told of the plan only a day in advance. He said watermen were frustrated at not being consulted in what he described as "a big top secret thing."

Still, he said DNR Secretary John Griffin assured him during a meeting that the state will work with watermen. "They said they would work something out with us, so we'll see what happens," Simns said.

The plans will undergo public review before final regulations can be enacted in the spring.

But with habitat and oyster populations at all-time lows-and oyster survival often dictated by variables such as the amount of rainfall-Naylor cautioned that recovery will require a long-term commitment. "We're talking about multi-decadal time frames to really understand the implications of what we're doing," he said.

The Associated Press contributed to this report