VIMS

Blue crab stock healthy with above average abundance

  • Callinectes sapidus
    Callinectes sapidus  The Bay-wide Winter Dredge Survey determines the status of the blue crab population in Chesapeake Bay.  David Malmquist
  • VIMS Dredge Survey team
    VIMS Dredge Survey team  Members of the VIMS Dredge Survey team in action. From L: Captain Durand Ward, Mike Seebo, and Kathleen Knick prepare to deploy the crab dredge from the R/V {em}Bay Eagle{/em} at a site in the York River.  David Malmquist
  • Cleaning the Dredge
    Cleaning the Dredge  The survey team drags the crab dredge through the water to dislodge mud before it is brought on deck for sorting.  David Malmquist
  • Dredge Retrieval
    Dredge Retreival  Captain Durand Ward and Kathleen Knick empty the crab dredge onto the deck of the R/V {em}Bay Eagle{/em} for processing as Mike Seebo watches for crabs.  David Malmquist
  • Emptying the Dredge
    Emptying the Dredge  Alison Smith and Kathleen Knick dump a dredge sample from a sandy site in the York River onto the deck during the Blue Crab Winter Dredge Survey.  David Malmquist
  • Sorting the Catch
    Sorting the Catch  Alison Smith, Mike Seebo, and Kathleen Knick carefully sort through hydroids and other dredged materials from a York River site in search of blue crabs.  David Malmquist
  • Recording Data
    Recording Data  Kathleen Knick records survey data aboard the R/V {em}Bay Eagle{/em} during a dredge tow.  David Malmquist
  • Crab Tagging
    Crab Tagging  A VIMS researcher tags a mature female blue crab collected during the Winter Dredge Survey. Recapture of tagged crabs provides data about crab movement, survival, and effectiveness of Virginia's blue-crab spawning sanctuary.  David Malmquist
  • Navigation
    Navigation  The survey uses a crab dredge to sample blue crabs at 1,500 randomly selected sites throughout Chesapeake Bay between November and March. By sampling during winter when blue crabs are buried in the mud and stationary, scientists can develop estimates of the number of crabs present in the Bay. Here's a computer map of three dredge paths near the mouth of the York River.  David Malmquist
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Female blue crab abundance in 2019 will benefit spawning and improve fisheries opportunities

Results from the latest Blue Crab Winter Dredge Survey—conducted annually by the Virginia Institute of Marine Science and Maryland Department of Natural Resources—show the Chesapeake Bay’s blue crab stock remains healthy and able to support quality commercial and recreational harvests.

The results—available due to months of field sampling and laboratory analysis by VIMS researchers Mike Seebo, Katie Knick, Gabby Saluta, Alison Smith, and colleagues at Maryland DNR—were announced by the Virginia Marine Resources Commission and Maryland DNR leadership.

Professor Rom Lipcius, who oversees operation of the Blue Crab Winter Dredge Survey at VIMS, says "Due to effective fishery management actions taken in 2008 and 2009, the blue crab population in 2019 remains healthy and resilient to environmental disturbances, such as hurricanes or heavy rains, and to biological pressures, such as periodic increases in predation by fish including red drum and striped bass."

Blue crabs are a Chesapeake Bay icon and important commercial and recreational species. © VIMS.“Our marine resources are a treasure and the blue crab is an important Virginia species that demands responsible management,” said Governor Ralph Northam in the VMRC release. “I trust our managers and scientists will utilize the best information possible, along with the input of stakeholders, to ensure the continued success and longevity of this fishery.”

The combined abundance of all sizes of blue crab in the Chesapeake Bay in 2019 was 594 million, ranking 8th among the 30 years VIMS and MD DNR have conducted their bay-wide survey. Successful commercial and recreational harvest within the Chesapeake Bay depends on all sizes of blue crab at one time or another during the season, and those benefits can be supported by this year’s overall abundant crab stock.


"It's no surprise that cleaner waters, more seagrass and oyster reef habitat, and responsible catch limits have produced an upward trend in blue crab abundance," said Virginia Secretary of Natural Resources Matthew Strickler in the same release. "This shows the kind of direct economic benefits that cleaner water and science-based management have for Virginians, and it is why Governor Northam's new Chesapeake Bay Blueprint to achieve our clean water goals by 2025 is so important."

“Although these abundance estimates underscore a stable blue crab resource, we still must exercise caution as we manage this iconic resource," added VMRC Commissioner Steve Bowman. "While no reductions appear necessary, we must realize that to adopt overly liberal harvest measures would be irresponsible. I look forward to input from our staff, harvesters, and the public as we craft a balanced plan that ensures continued stability in what has been in the past a somewhat fragile resource.”

The recent survey indicates a total abundance of 271 million adult male and adult female crabs. This is 31% higher than in 2018 and remains well above the 30-year average of 199 million crabs. Lipcius attributes the higher than normal abundance estimates for all life stages to "An abundant spawning stock over the past few years and favorable environmental conditions in 2018, such as the mild winter."

The abundance of mature female crabs, which will spawn in late May or mid-summer of 2019, was estimated at 190 million—above the 1990-2019 average of 126 million. This 2019 abundance of potential female spawning crabs is 29% higher than in 2018. The abundance of spawning-age female crabs has averaged 163 million during the last 10 years, as compared to the average of 82 million from 1998-2007, an era that coincided with several overfishing events. Since 2008, overfishing has not occurred. The 2019 female spawning stock is the 5th-largest since the survey began and remains well above the minimum safe threshold of 70 million crabs.


Alison Smith and Durand Ward prepare to deploy the crab dredge from the R/V Bay Eagle at a site in the York River. ©D. Malmquist/VIMS.This year’s survey results also show a 93% increase in the abundance of juvenile crabs—those measuring 2.4 inches or less in carapace width—from 167 million to 323 million. These young crabs will grow large enough for harvest by commercial and recreational fisheries late in the summer and represent the major contributor to next year’s reproductive effort. The continued abundance of juvenile blue crabs in the Bay depends on many environmental and biological factors.

The 2018 Bay-wide commercial harvest increased by 2% from the previous year to 55.2 million pounds. Harvest has been relatively stable the past 4 years, and was 50% above the 30-year lows observed in 2013 and 2014. The 2018 Virginia commercial crab harvest was 21.2 million pounds, comparable to the 10-year average (2009-2018) of 22.3 million pounds. Virginia commercial crab harvests are moderated by blue crab abundance, as well as marketing and processing constraints.

 Alison Smith deploys a sensor to record water temperature, salinity, and dissolved oxygen readings during the Blue Crab Winter Dredge Survey. The data are compared to dredge survey results to better understand blue crab distribution, habitat use, and behavior.The Winter Dredge Survey, which VIMS and Maryland DNR have conducted annually since 1989, is the primary census of the Bay’s blue crab standing stock. Survey scientists employ crab dredges that sample blue crabs at 1,500 sites throughout the Chesapeake Bay. Sampling during winter, when blue crabs are usually buried in the sediment and stationary, allows them to develop, with good precision, estimates of the number of crabs present in the Bay.

The Chesapeake Bay Stock Assessment Committee, a subcommittee of the Sustainable Fisheries Goal Implementation Team, is reviewing the recent survey results and will release its full analysis in its 2019 Blue Crab Advisory Report this summer. The annual advisory report is used by managers as they review and update fishery regulations. The Bay jurisdictions continue to cooperatively manage the Bay-wide blue crab stock.

The VMRC will begin discussions with the Commission’s Crab Management Advisory Committee to provide guidance to the Commission concerning the course of action for 2019 that promotes the health of the blue crab stock and its fisheries. The Commission will be briefed on these survey results at its May 28 meeting.