State officials called the rule changes "modest but important."
"Since the release of the winter dredge survey, experts have cautioned that a scarcity of juvenile crabs could result in more challenging harvest conditions later this year and next," state Natural Resources Secretary Mark Belton said in a statement. "This decision is the result of partners in science and industry developing consensus to achieve what is best for the health and ongoing productivity of the Chesapeake Bay blue crab fishery."
The decision caps off an annual process that had become controversial when Belton fired the state's longtime crab fishery manager in February. Watermen and environmentalists said they believed Brenda Davis was terminated because many crabbers viewed her as inflexible to their requests that harvest rules be loosened.
The annual winter crab survey, in which researchers count the crustaceans by dredging them from their muddy burrows, found that the Chesapeake crab population fell from a near-record high of 550 million in 2016 to 455 million this year.
The losses were attributed to a 54 percent drop in the juvenile crab population, and came despite a record-high count of adult female crabs.
A panel of scientists that advises Maryland, Virginia and the Potomac River Fisheries Commission on crab science said that based on the data, officials should "maintain a cautious, risk-averse approach" to help crab numbers rebound.
Under the revised regulations, Maryland's crab season will end Nov. 20, 10 days earlier than the extended 2016 season did. During November, crabbers will also be limited to catching fewer bushels of adult females than last year.
Virginia officials were also expected to adopt rules Tuesday setting an earlier end date to the crabbing season than in 2016. Both Maryland and Virginia extended the season by three weeks last year after the annual survey showed one of the highest crab populations in two decades.
The bay's crab population is naturally prone to swings because the crustaceans rely on favorable currents and temperatures to make it from Virginia spawning grounds to their earliest days in the Atlantic Ocean to their final homes in the Chesapeake and its tributaries. The average crab lives two years.