Saying that the Bay’s blue crab population is close to “collapse,” the Chesapeake Bay Foundation has called for establishing a sanctuary in all portions of the Bay deeper than 40 feet — putting about one-quarter of its tidal area off-limits to crabbing.

The intent of the sanctuary, which the CBF said should be implemented in September, is to provide a zone of “safe passage” to female crabs that migrate down the Bay to spawn. CBF has sent its proposal to natural resource officials in Maryland and Virginia.

“While some have suggested we need not act until a collapse, we believe it is the responsibility of fisheries managers to avoid a collapse and prevent all the social and economic repercussions that would accompany one,” CBF President William Baker said.

Over the past six years, the Bay’s blue crab population has declined by 34 percent, according to an annual winter dredge survey funded by the National Atmospheric and Oceanic Administration’s National Marine Fisheries Service. Last winter’s survey showed a 15 percent decline from the previous year.

Concern about the health of the population has triggered NOAA to conduct a “stock assessment” of the Bay’s blue crabs in which a team of scientists will try to define the condition of the crab population and the degree to which it is impacted by fishing pressure.

Both Maryland and Virginia have adopted measures to reduce harvests in the past two years, and both states have special studies under way to determine whether the continued decline warrants further actions.

Immature females are found throughout the Bay during the summer. After mating, the “mature” females migrate down the Bay in the fall and spring until they reach the mouth of the Bay where they release between 750,000 and 8 million eggs apiece the following summer.

During that migration, the crabs are the target of both a pot fishery in Maryland and pot and dredge fisheries in Virginia. Many scientists attending a recent meeting in Annapolis to discuss the blue crab situation said management efforts should be aimed at making sure more female blue crabs survive long enough to reproduce.

CBF, while supporting previous actions taken by the states and their current study groups, said the sanctuary should be established as an interim measure to protect crabs this fall as they begin migrating while the states complete their work on a more comprehensive strategy.

“We feel this is the fairest way to quickly address the overharvesting of blue crabs,” Baker said in a letter to state officials. “If implemented by both states, this proposal would distribute the burden equitably among the various watermen and between Virginia and Maryland.”

The deep-water sanctuary, according to CBF, would protect about half the mature females as they migrate down the Bay. In addition, CBF said, it could be easily enforced and would equitably affect the many different parts of the blue crab fishery, which utilize a variety of gear and techniques to catch crabs.

Bill Goldsborough, a fisheries scientist with the foundation, said the 40-foot-depth was the chosen to “pick the right balance” between protecting the crab and allowing a sustainable harvest. “It may be that there is a more optimal depth to achieve that balance.”

Ultimately, he said, the sanctuary could be folded into plans being developed by the states which may target specific parts of the crab fishery for restrictions. “It’s not meant to be the only thing you need to do for blue crabs,” he said. “It’s something geared toward providing a measure of protection for mature females, something we feel we need to do in the short term.”

Blue crabs are the Bay’s most valuable remaining fishery, with an annual value estimated at $186 million.

But Rom Lipcius, a crab specialist at the Virginia Institute of Marine Science, said the foundation overstated the plight of blue crabs. “Our data does not indicate that it is near collapse,'” Lipcius said. “Our data indicates that our population is in a low phase."

Lipcius also said the concept of creating sanctuaries in the middle of the Bay has not been thoroughly studied and that other forms of regulation, such as limiting the number of crab pot permits or the number of pots per waterman, might be better ways to reduce the strain on crab populations.

“We are in agreement with the idea that there needs to be some cap in the fishery across the board,” Lipcius said. “But we certainly can’t advocate that specific proposal.”

State officials, meanwhile, said they would study the proposal.

Sarah Taylor-Rogers, Maryland's assistant secretary of natural resources, said she did not know what the likelihood is that the foundation’s proposal could be adopted by September. To be effective, it would need to be put in place by both states, she said.

“But pressure has been great on our female crabs,” she said. “We may need to put something into place this fall with respect to female crabs.”

In Virginia, the proposal will be taken up by a special panel appointed by the General Assembly to study the blue crab issue.

“They have said they will take the foundation’s proposal and include it as another element to be studied,” said Wilford Kale, spokesman for the Virginia Marine Resources Commission.

The study group, Kale said, has been reluctant to “get into the final decision-making process” until the results of NOAA’s stock assessment are available this fall.

But, Kale added, if the situation changes dramatically, the VMRC could take action before the General Assembly returns to Richmond next January and reviews the panel’s recommendations.