Survey shows spike in young crabs, but overall count down
DNR says winter numbers indicate slow start, but better season could still follow
A newly released winter survey showed an increase of juvenile crabs this year in the Chesapeake and its tributaries. But the numbers of adult male and female crabs both dropped, bringing the overall baywide crab population down by tens of millions when compared to last year.
The decline in adult crabs could mean a slow start to this harvest season that started in April, but watermen said things could improve as young crabs grow into market size in mid-summer.
“They sort of tell us it’s gonna be late in the year before we have a larger number of adult crabs,” said Tommy Zinn, president of the Calvert County Watermen’s Association. “Having an increase in juvenile is a good sign, meaning the future looks better down the road though we will have a slow period in between.”
Considering the unusual cold spell from February through April, Zinn said in a phone interview Wednesday he’s not surprised by the results.
“We were not expecting good numbers from the survey, not on the adult crabs,” he said. “A lot of them died because when they came out of their hibernation state, [because] it got super cold. It shocked them and killed them.”
According to the Maryland Department of Natural Resources, this year’s cold weather and ice cover took a toll on the adult crab population, causing an estimated 35 percent mortality of adult females wintering in state waters.
Willy Dean, president of the St. Mary’s County Watermen’s Association, agreed that the cold winter had some negative effect on the adult crabs, though he said it’s hard to say how much.
“It’s gonna be a very, very tough season,” Dean said Wednesday over the phone. “We just need to ride this one out.”
In addition to the bad weather, Dean thinks the growing numbers of rockfish and blue catfish also have something to do with fewer adult crabs in the bay.
“A lot of it is predation,” he said, noting he has seen more rockfish himself and has heard that there’s an increasing amount of blue catfish, especially farther up in the Potomac River.
Zinn said he’s heard the same thing about the blue catfish. As crabs shed their shells to grow, that process makes them highly vulnerable to predators like catfish during those periods.
“Like crabs, catfish are bottom feeders, too,” he said. “If there’s an abundance of catfish, they can take a toll on the number of crabs.”
Biologists use dredge equipment each winter to capture, measure, record and release blue crabs at 1,500 sites. According to the annual survey conducted by Maryland DNR and Virginia institute of Marine Science from December through March, baywide crab population is estimated to be 371 million, a 20 percent drop from last year’s 455 million, driven largely by the smaller numbers of adult crabs.
In 2018, DNR said the spawning female stock decreased more than 40 percent from a record high of 254 million to 147 million, dropping below the target level of 215 million, but remaining above safe levels.
Adult male crab abundance declined 23 percent from 76 million to 59 million. The juvenile crab population increased 34 percent over last year, reaching 167 million.
“Even with the erratic weather, which included snow in April, the blue crab population remains well within parame- ters, showing that the state and our partners are managing the species well,” DNR Secretary Mark Belton said in a release Wednesday.
The 2017 baywide crab harvest level also decreased, dropping from 60 million to 54 million pounds, according to DNR.
“This year’s results give us optimism that our management approach is effective at conserving adequate numbers of crabs even when the number of juveniles is low and winter mortality is high,” DNR’s Fishing and Boating Services Director David Blazer said in the same release.
But at the end of the day, Zinn said the results should be viewed with a grain of Old Bay. “You can’t put too much faith into what the survey shows,” he said.
One year, for example, the survey predicted a bad year but watermen ended up having an above-average season, he said. Another time, the survey indicated a good year, but watermen struggled to find enough crabs.
Considering that many variables could affect the harvest, “what [the surveyors] see in January and February doesn’t mean that’s what it’s gonna be like in May or June,” he said. “It’s Mother Nature.”
Tommy Zinn throws back an undersized crab off his boat when trot lining in the early morning last August on the Patuxent River near Hellen Creek.