Wednesday, October 5, 2022

Blue crab survey shows possible shortage in late summer

The blue crab Callinectes sapidus. (WYDaily/Courtesy VIMS)
The 2021 Blue Crab Winter Dredge Survey shows an increase in female crab populations but a decrease in juvenile and male crabs. (WYDaily/Courtesy of VIMS)
REGIONAL — Crab season can either look very promising or a little sparse this year, according to a new survey.
On Friday, the Virginia Marine Resources Commission and the Maryland Department of Natural Resources released the results of their 2021 Blue Crab Winter Dredge Survey, an annual estimate of the population of blue crabs in the Chesapeake Bay and its tributaries.
While the results showed a slight increase in mature female crab levels when compared to last year, juvenile crab numbers decreased to the lowest level since the survey began in 1990.
“The results of this year’s survey are definitely a mixed bag,” said Chesapeake Bay Foundation Senior Regional Ecosystem Scientist Chris Moore in a released statement. “The reduced abundance of juveniles and males could make crabs scarce later this summer into the fall for those who enjoy eating crabs, and indicates we should remain cautious in our approach to managing this valuable fishery.”
The survey, which has been conducted annually since 1990 by the Virginia Institute of Marine Science (VIMS) and Maryland Department of Natural Resources, involves scientists employing traditional crab dredges to sample blue crabs at nearly 1,500 sites throughout the Chesapeake Bay from December through March, including some sites along the James and York rivers.
During the winter, blue crabs are buried in the mud and sedentary, making it the best time for scientists to develop estimates of the number of crabs present in the Bay.
According to a release from VIMS, the abundance of spawning-aged females increased 12% from 2020. The estimated 158 million spawning females remains well above the overfished threshold of 72 million crabs, but below the target abundance of 196 million crabs.
Based on results from the 2017 update to the blue crab stock assessment, that threshold and target were recently revised.
Female blue crabs can spawn an average of three million new crabs each brood and release about three broods per year. This makes them the cornerstone of programs such as the joint Virginia-Maryland blue crab management program, which established a fisheries management framework to conserve the spawning population.
As for the number of juvenile and male crabs, Moore said even though the juvenile population estimates tend to fluctuate, the low estimate this year emphasizes the continuing need to protect spawning females and to consider precautionary measures to protect juveniles so that they can mature into the spawning age.
“Reducing pollution to the Bay is another key to a healthier crab population, as cleaner waterways and more underwater grasses will provide improved crab habitat, particularly for juveniles,” Moore said in a released statement.
While results from last year’s surveys warrant no further management actions, new regulations could be placed later in the year if juvenile populations remain low, according to VIMS.
VIMS also noted the Chesapeake Bay Stock Assessment Committee (CBSAC) held a working meeting last week to discuss the results from the 2020-21 Winter Dredge Survey, which will be published in a the full CBSAC Annual Report this June, and to provide insight on what conditions may have influenced the 2021 crab abundance.
The Bay jurisdictions will meet in the next few weeks with their respective blue crab advisory panels and commissions to establish crabbing regulations for the upcoming management season that begins in July.
To view the results of the 2021 Blue Crab Winter Dredge Survey, click here.
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