VIMS

Winter survey supports 2008 blue crab management actions

  • 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 Retreival
    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
  • Water Conditions
    Water Conditions  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.  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
Photo - of -
Governors O’Malley and Kaine announce increase In Bay blue crab population

ANNAPOLIS, MD and RICHMOND, VA—Virginia Governor Timothy M. Kaine and Maryland Governor Martin O’Malley today announced the Chesapeake Bay’s adult population of blue crabs has increased substantially over last year, indicating management measures put into place in 2008 to address population declines are working.

The results of the most recent Bay-wide winter dredge survey, which is conducted annually by the Virginia Institute of Marine Science (VIMS) and the Maryland Department of Natural Resources (DNR), estimate the total number of crabs overwintering in Chesapeake Bay during 2008-2009 has increased from 280 million in 2007-2008 to just over 400 million.

“This is terrific news and a great first step, but this does not mean the problem is solved,’’ Governor Kaine said. “This scientific survey clearly shows we are on the right path but we need to continue our conservation efforts to rebuild this environmentally and economically vital species. I want to thank our crab industry for their support and endurance through these difficult times.”

The increase in abundance is primarily due to a striking increase in the number of adult female crabs, nearly double last year’s estimate. Coupled with a 50 percent increase in abundance of adult males, overall adult abundance in 2008-2009 is estimated to be approximately 230 million crabs—slightly more than the interim target level of 200 million set by the Chesapeake Bay Stock Assessment Committee in early 2008.

Despite the adult population increase, the abundance of young-of-the-year crabs (less than two inches across the carapace) did not change measurably from last year, and remains below the 18-year survey average.  These crabs will become vulnerable to the fisheries late in the 2009 season and represent the 2010 spawning potential.

“The success of these management measures sets the stage for the next step of recovery for the Bay’s blue crab, an increase in juveniles that we hope to see next year,” Governor O’Malley said.  “The ultimate challenge, of course, is to achieve a sustainable crab fishery and maintain it over time.”

“We recognize that this success did not come without unavoidable economic impact to those who work in Maryland’s crabbing industry,” added Governor O’Malley. “I thank them for their conservation efforts and remain committed to mitigating the impact of conservation measures on our working families as we work to create a more profitable and sustainable crab fishery.”

Last spring, in response to scientific data that showed the Bay-wide population of blue crabs had plunged 70 percent since 1993, the two Governors agreed to work collaboratively on a Bay-wide effort to rebuild the species by reducing the harvest of the spawning stock of female blue crabs by 34 percent in 2008.

At that time, scientists from both states deemed conservation measures necessary as blue crabs suffered near-historic lows in spawning stock.  Despite the states’ shared harvest target of 46 percent, in place since 2001, the combination of low abundance of crabs and continuing high fishing pressure led to more than 60 percent of the Bay’s crab population being harvested in 2007.

Overall, the survey indicates that the 2008 coordinated management actions implemented by the State of Maryland, the Commonwealth of Virginia, and the Potomac River Fisheries Commission, were collectively effective at increasing the abundance of spawning–age females, a major goal of the 2008 conservation measures. These adult females will spawn this summer, and the resulting young crabs will be measured as young-of-the-year during the 2009-2010 survey.   It is expected that the large number of mature female crabs conserved last year will significantly increase the chances of a strong spawn in 2009.

“The sharp increase in crab abundance was not a random event, nor was it due to improved environmental conditions. It was clearly due to the recent management actions," said Dr. Rom Lipcius, who directs the VIMS component of the dredge survey. “Now, we have to ensure that these females survive to spawn this summer, and that their offspring produce a healthy spawning stock in coming years.”

Based on winter dredge survey results, Maryland and Virginia may allow for a slight increase in the harvest of female crabs, while still focusing on the shared goal of restoring the fishery and ensuring that no more than 46 percent of the available crabs are removed in any year.  The details of any changes to catch limits and or closing dates will be developed in coordination among the management jurisdictions and in consultation with stakeholders. Changes are anticipated by the end of May.

The Bay jurisdictions will be working through 2009 to establish long-term management approaches that will maintain focus on annual removal rates, improve the efficiency and predictability of blue crab management (i.e., develop harvest allocation by jurisdiction) and increase the level of certainty in our management actions (i.e., addressing latent effort).

In September 2008, Maryland and Virginia were each awarded $10 million in federal blue crab disaster funds from NOAA‘s National Marine Fisheries Service, in response to a request from Governors O’Malley and Kaine, and advocacy by the Maryland Congressional Delegation under the leadership of Senator Barbara Mikulski. Each State also expects to receive $5 million in additional federal disaster funding as a result of recent federal budget action.

In addition to crab management measures to achieve harvest reductions, Virginia has undertaken additional bold regulatory and funding initiatives to significantly reduce pollutant loads from point sources, agricultural lands and urban stormwater, which are negatively impacting the Bay’s crab population.

The Bay-wide blue crab winter dredge survey is a cooperative effort between DNR and VIMS, and is the primary survey used to assess the condition of the Chesapeake Bay blue crab population. Since 1990, the survey has employed crab dredges to sample blue crabs at 1,500 sites throughout the Chesapeake Bay from November through March. By sampling during winter when blue crabs are buried in the mud and stationary, scientists can develop, with good precision, estimates of the number of crabs present in the Bay.

Estimates of abundance are developed separately for young-of-the-year crabs, mature female crabs, and adult male crabs. Together, these groups of crabs will support the 2009 fishery and produce the next generation of crabs. In May, the NOAA Chesapeake Bay Stock Assessment Committee (CBSAC) will conduct a complete examination of the blue crab data including dredge survey results and 2008 harvest information. The results of this analysis will be presented in the 2009 Blue Crab Advisory Report to be released in late summer of 2009.

“It is very gratifying to see success in our efforts to rebuild the crab population, and some financial help for our hard-hit crabbers,” said Governor Kaine. “The crab population is stabilizing but we need to maintain discipline and stay the course. We are now in a position for the next phase of the recovery. We dare not backslide.”