MA - Chesapeake Bay blue crabs are increasing in numbers
The Chesapeake Bay’s blue crab population is showing encouraging signs of a rebound from recent record lows, according to the 2023 bay-wide Blue Crab Winter Dredge Survey.
The abundance rate for bay blue crabs in all categories increased from 227 million to 323 million, according to the report.
Although the spawning stock has returned to healthy levels, fisheries managers remain cautious about the continued trend of low juvenile abundance, according to Zachary Widgeon, a spokesperson for the Virginia Marine Resource Commission.
All categories of blue crab, by sex and by age, have increased since the 2022 survey. Adult crabs drove this increase, with adult males nearly doubling and adult females returning to above average levels. According to current biological reference points, Widgeon said, “female blue crabs in the Chesapeake Bay are not overfished and overfishing is not occurring, due to successful management of the bay’s blue crab fisheries.”
Widgeon said, “Scientists and managers agreed a robust abundance of adult female crabs is integral to the success of the crab population. Each female can spawn on average up to nine million eggs per year. The 2023 adult female abundance of 152 million crabs is promising, though it remains below the target abundance of 196 million crabs,” Widgeon added.
“We’re pleased to see over a 50 percent increase in the adult female numbers in 2023,” said Jamie Green, Commissioner of the VMRC. “These results are encouraging, and we’ll continue working diligently with our partners in the Chesapeake Bay to increase blue crab stock numbers.”
The abundance of juvenile crabs tempered population growth by remaining low at 116 million crabs. The juvenile populations from 2021 through 2023 rank amongst the six lowest in the 34 years of the Winter Dredge Survey.
“The low abundances seen in 2022 spurred interest in a new benchmark stock assessment for blue crabs, allowing researchers to incorporate new data and test new models since the last assessment was conducted in 2011,” Widgeon reported. “This process began in September 2022 with a blue crab science workshop that sought to characterize impacts on the blue crab population from a variety of influences, including water quality, predator abundance, and availability of habitat.” The assessment is scheduled to be completed and peer reviewed in 2025.
The Winter Dredge Survey is conducted annually by the Virginia Institute of Marine Science and the Maryland Department of Natural Resources. Since 1990, the survey has utilized traditional crab dredges to sample blue crabs at 1,500 sites throughout the Chesapeake Bay from December through March.
By sampling during winter when blue crabs are sedentary and buried in the mud, scientists can develop more precise estimates of the number of crabs in the bay. Adult females observed in each survey are likely to spawn during the following early- to mid-summer period, contributing to next year’s juvenile population.