Data offers good news, but not good news for the Chesapeake Bay crab population | news / arlington
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The number of blue crabs in Chesapeake Bay this winter fell to the fourth lowest on record, new data shows, largely due to the worst ever index of juvenile crabs since an annual survey began in the bay scale in 1990.
Although the decline in juveniles is worrying, fishery managers say the number of adult females remains high. They are hoping the females will produce a better crop of juveniles when they breed later this year.
This year’s winter drag survey, which provides an annual snapshot of the health of the blue crab stock, estimated that the Chesapeake had 282 million crabs, the lowest number since 2007. That figure only includes 81 million juveniles, the lowest in the history of the survey.
The number of young crabs naturally varies from year to year. Females release their larvae near the mouth of the bay in the fall, which then float into the ocean. The number of juvenile crabs that survive and return to the Chesapeake is highly dependent on weather conditions, currents and other variables outside the bay each winter.
Because these conditions cannot be controlled, fisheries managers in 2008 adapted a strategy to ensure that a sufficient number of adult females survive the pressure of harvest each year to produce a strong harvest of eggs. The hope is that the large number of eggs they produce will encounter favorable coastal conditions often enough to keep the overall population healthy.
The survey revealed a healthy female population: 158 million, the 10th highest number since the survey began, and well above the 72.5 million that scientists believe is the minimum number needed to protect the stock.
“We are comfortable with where we are now with the abundance of females,” said Mike Luisi, director of the Fisheries Monitoring and Assessment Division of the Maryland Department of Natural Resources.
“What we want to do is make sure there are enough females and enough males to provide a juvenile year class,” Luisi. “Sometimes it’s good, sometimes it’s less than good. This year it was not good.
Because the number of female crabs remains high, fisheries managers say they have no plans to change the crab catch rules immediately, although they will monitor information on the crab stock. during the summer.
“Based on the results of the investigation, we will not be expanding the crab fishery this year,” said Steven Bowman, head of the Virginia Marine Resources Commission.
While management has focused on protecting the abundance of female crabs, another figure from this year’s survey may cause concern: it found only 39 million adult male crabs, well below of the long-term average of 77 million.
“The reduced abundance of juveniles and males could make crabs scarce later this summer in the fall for those who enjoy eating crabs, and this indicates that we must remain cautious in our approach to managing this valuable fishery.” said Chris Moore, regional senior ecosystem scientist. with the Chesapeake Bay Foundation.
The Chesapeake Bay Stock Assessment Committee, made up of scientists and fisheries managers and administered by the Chesapeake Bay office of the National Oceanic and Atmospheric Administration, will review data from the dredging survey and issue a report later this summer.
The winter dredging survey, conducted annually by MNR and the Virginia Institute of Marine Science, samples blue crabs at 1,500 sites across the bay.
Bay Journal editor-in-chief Karl Blankenship is the founding editor-in-chief of the Bay Journal and the Bay Journal Media. This article first appeared on Bayjournal.com and in the printed issue of the June 2021 journal.