Fewer blue crabs were found this winter in the Chesapeake Bay, a recently completed survey indicates, adding to scientists' worries that one of the region's most prized delicacies is in jeopardy.
Meeting in Annapolis this week, biologists from Maryland and Virginia concluded that there are a growing number of "warning signs" pointing to diminished blue crab stocks in both states.
Most also worried that unless future catches are limited, the crab may not be able to bounce back readily from the coming harvest season.
"Prudent management suggests we should at least regulate efforts to prevent a collapse," said Dr. Romuald N. Lipcius, an associate professor with the Virginia Institute of Marine Science. "A collapse is not imminent, but we have to be cautious."
Maryland's crab harvest fell to just 26 million pounds in 1992. It rebounded to 57 million pounds the next year, before dropping again to 36 million pounds last year -- about one-fifth below the 10-year average.
But researchers believe that harvest numbers alone are misleading because they only document how many crabs are caught, not how many are in the bay. Recent studies suggest that watermen are putting more pressure on a smaller population, and that the recreational catch has been greatly underestimated.
The latest survey results, based on dredging more than 1,000 bay bottom sites in Maryland and Virginia between December and March, found 15 percent fewer crabs than in the winter of 1994, which was also a subpar year.
Wintering crabs are considered crucial to future harvests. Late in the year, crabs migrate south and burrow in the mud, emerging in the spring to spawn.
By itself, the dredging index might not set off alarm bells. But samples collected by Virginia trawl nets have yielded steadily declining numbers since 1990, reaching a record low last year.
In a meeting Thursday sponsored by the National Oceanic and Atmospheric Administration's Chesapeake Bay office, the nearly two-dozen participants puzzled over the extent of the problem. The bay's crab populations have always bounced up and down, and are subject to little-understood environmental influences.
"You're never going to get perfect information in biology," warned William J. Goldsborough, a senior scientist with the Chesapeake Bay Foundation. "But there are sufficient warning signs that we ought to act."
John R. Griffin, secretary of the Maryland Department of Natural Resources, said the latest information is not "any great shock." But the data has drawn his attention.
"I don't think we're falling off the cliff with alarm," Mr. Griffin said. "We're at a point where we're concerned."
He is seeking a full review of all information regarding crab stocks in coordination with Virginia officials. In August, he said, a decision will be made whether to impose additional harvest restrictions this year or next.
Virginia officials are also concerned, but said they would be reluctant to impose more rules on watermen this year.
Harvest regulations that went into effect Jan. 1 have not had a chance to work yet, said Jack Travelstead, fisheries manager for the Virginia Marine Resources Commission.
"What we need to do is keep an eye on the size of the spawning stock," Mr. Travelstead said.
Crabs are a politically volatile issue in Maryland and Virginia. With historic declines in the Chesapeake Bay's other harvests -- fish, oysters and clams -- crabs have become of paramount importance, both economically and symbolically.
Biologists said they are reluctant to cause further economic hardship to watermen, nor do they want to sound an alarm unnecessarily. But they are also fearful that watermen would suffer more if crab stocks became depleted.
"There's a lot of room for uncertainty here," said L. Eugene Cronin, a longtime bay scientist. "It's a very complex species."