The ladies-first management strategy has paid off for the Bay's blue crab population according to a new study, which holds out the possibility that crab numbers may rebound to levels not seen in two decades.

The first stock assessment for blue crabs since 2005 recommended that managers continue conservative management of female crabs with the aim of boosting the Baywide population of adult females to 215 million, as measured in the annual Baywide winter dredge survey.

That's a huge jump over the current interim Bay target of 200 million for all adult crabs. Nonetheless, the assessment said the numbers of female crabs in the Bay routinely exceeded the target of 215 million adult females from 1980 through 1990. Since then, however, it has approached that level only three times: 2010, 1993 and 1991.

If jurisdictions reach and maintain the recommended target level, the assessment said that blue crabs eventually should produce sustainable harvests in the range of 400 million to 600 million crabs a year, or 133 million to 200 million pounds.

Tom Miller, a fisheries scientist at the University of Maryland Center for Environmental Science, who led the stock assessment team, said that level of abundance might be achieved in about five years, or three generations of blue crabs.

"I think that would be enough to really change abundance," he said.

The assessment also proposes a new harvest threshold catch of 34 percent of female crabs. Any catch beyond that level would constitute overfishing and put the stock at risk. That translates into protecting a minimum of 70 million adult female crabs, and 135 million total adult crabs.

The assessment, which included a new analyses of past population levels, confirmed that overfishing of the crab stock had taken place from 1998 through 2004, and indicated that the stock had been in even worse shape than previously realized.

Crab catches began declining in the late 1990s, and states reacted with new restrictions in 2000. Nonetheless, the Baywide population still hovered near historic lows, prompting the governors of Maryland and Virginia to slash harvest of female crabs by a third starting in 2008 in the hope of jump-starting the production of young crabs to boost the population.

That worked, the assessment indicated. From 1994 through 2006, females made up 62.8 percent of the crab harvest. In 2008 and 2009, that dropped 10 percent.

The population responded with the winter dredge survey estimating a crab population of 223 million crabs ages 1 or older in 2009, 315 million in 2010 and 254 million in 2011. That was the first time since the early 1990s that the adult blue crab population exceeded the 200 million level for three consecutive years.

The new blue crab stock assessment, which was funded by the National Oceanic and Atmospheric Administration's Chesapeake Bay Office, was the first gender-specific review of the stock, and the first to make sex-specific recommendations on stock sizes.

Miller said the states deserved credit for acting to protect females, especially Virginia, where the catch was most heavily skewed toward females. Part of that is because its winter dredge fishery - now closed - targeted females. It is also partly due to females migrating toward the mouth of the Bay to spawn, which makes them more likely to be caught than males, which are more sedentary.

"Because the females are moving, they are more likely to encounter the crab pots," Miller said.

Peyton Robertson, who heads NOAA's Bay Office, said the assessment reflected years of research, which has allowed states to continually improve blue crab management. "People said years ago that the natural variability in the blue crab stock and the factors that affect it were so diverse that you could never really manage this fishery, and that has been proven wrong," he said.

This fall, the Chesapeake Bay Stock Assessment Committee, which is made up of fishery managers and scientists, will review the assessment and make management recommendations.