The Chesapeake Bay's population of blue crabs inched up to its highest level in several years in 2003 as watermen plucked fewer crabs from the bay, according to a report released yesterday.

Juvenile and adult crabs, as well as female crabs of reproducing age, all seemed to be more abundant than in any year since 2000, according to the report based on four surveys and compiled by a group of scientists called the Chesapeake Bay Stock Assessment Committee.

But, even after the increases, the crab populations remain below the average from previous decades.

"It's a mixed message," said Chris Bonzek, a fisheries data analyst who heads the assessment committee. "We're not worse. It's too soon to say we're definitely getting better."

One reason for the population increase, scientists said, could be new regulations in Maryland and Virginia that limit the time watermen can spend fishing for crabs or the size of the creatures they can harvest. The 2003 crab harvest amounted to 48 million pounds, compared with 52 million a year earlier and 69 million in 1999, according to the National Oceanic and Atmospheric Administration.

Last year marked the first time since 1997 that the harvest did not exceed the level that scientists consider to be dangerous overfishing, according to the report.

"You'd hope to see some kind of feedback . . . based on what we've been doing," said Derek Orner of NOAA, which oversees the committee.

But Larry Simns, president of the Maryland Watermen's Association, said he doubted that the new regulations had caused much change. Instead, he said, changes in tides and temperature might be responsible.

"They try to give credit to the regulations," Simns said of the scientists. "Well, the regulations maybe had 10 percent, and Mother Nature probably had 90 percent" of the cause.

The report comes at a time that watermen have reported a sudden bumper crop in crabs, after years of declining harvests.

Simns estimated yesterday that this year's catch has been 10 times the size it was at the same time last year. He said that hard-shell crabs are so plentiful this year that their price has fallen from $120 per bushel to $60 or less.

Scientists have dismissed the notion that there is a sudden glut of crabs in the bay, arguing that warmer temperatures have simply gotten the crabs moving earlier than usual this year.

Simns remained skeptical of that explanation. "Mother Nature does a lot of things that man don't know nothing about," he said.

The report released yesterday does not provide a total number of crabs in the bay. Instead, it provides of an estimate of how prevalent the crustaceans were in 2003, compared with studies in previous years.

The study combined four surveys of crabs. Two were "trawl" surveys, in which crabs were scooped up off the bottom by a net. Another used "peeler pots" -- traps designed to catch crabs while they are molting -- set out in the bay near Calvert Cliffs in Southern Maryland.

The last method was a dredge survey, taken during the winter while crabs were hibernating in mud at the bay's bottom. A boat pulling a heavy metal dredge captured crabs under the surface.