New surveys conclude that the Bay’s blue crab population is “fully exploited” and the overall size of the spawning stock remains below its long-term average.

It’s the second straight year that surveys have shown that the harvest of crabs, the Chesapeake’s most valuable commercial species, has reached its maximum threshold without risking the stock. And, according to a new advisory report from the Chesapeake Bay Stock Assessment Committee, that is too close for comfort.

“Those are the ceilings that we don’t want to cross, and we’ve been kind of bumping our heads against that ceiling,” said Derek Orner, of the National Marine Fisheries Service, who is the CBSAC’s acting chair.

In its May report, which analyzed the latest figures from various surveys, the committee said there is an urgent need to set new fishing targets that are “distinctly lower and more risk averse than current threshold rates which are inappropriately interpreted as targets.”

Some scientists believe there has been so much fishing pressure that too many small crabs are being harvested. That could put the population at risk by taking too many reproducing adults out of the population. They argue that if fishing pressure were reduced, fewer — but larger and more valuable crabs — would be harvested. That could protect the health of the stock without hurting watermen.

The CBSAC and the Bi-State Blue Crab Advisory Committee, coordinated by the Chesapeake Bay Commission, are working together and hope to recommend new harvest targets by the end of next year.

The CBSAC’s advisory report found no trend in blue crab recruitment, the number of young crabs that enter the population each year. Maryland recruitment, though, was lower than Virginia’s.

But the spawning stock biomass, a measure of the reproductive potential of the population, remained below its long-term average, according to the advisory report — an indication that many crabs are being taken at a small size. Larger, heavier crabs usually produce more eggs than smaller ones. Spawning stock biomass has been below the long-term average since 1993.

The overall fishing mortality rate for blue crabs dropped last year. The reason for that isn’t clear, but some say it could reflect a sharp decline in fishing pressure in Maryland last summer and fall as watermen had difficulty finding crabs.

Last year’s Baywide harvest was 63.1 million pounds, the lowest since 1981. Still, blue crab harvests fluctuate year-to-year, and the CBSAC said the average harvest of the last three years — considered a better indicator than one year’s data — was 73 million pounds, close to the long-term average of 70 million.