Between 2019 and 2020, the abundance of adult (age 1+) female blue crabs in the Chesapeake Bay decreased 26% from 191 million to 141 million. This number is above the 70 million threshold which is considered to be the minimum sustainable level for female blue crabs in the Bay, but lower than the target of 215 million. Because of natural variability in annual blue crab populations, blue crab abundance fluctuates from year to year. For example, the 2020 abundance estimate of 141 million is a decrease from 2019, but similar to the 2018 estimate of 147 million female blue crabs.
Adult Female Blue Crab Abundance (1990-2020)
Blue crabs support commercial and recreational fisheries across the region. The female-specific reference points associated with this outcome—including a threshold of 70 million adult female crabs and a target of 215 million adult female crabs—were recommended in the 2011 blue crab benchmark stock assessment and adopted by Maryland, Virginia and the Potomac River Fisheries Commission (PRFC) in 2012. Where annual adult female blue crab abundance falls in relation to these numbers informs management decisions for the blue crab fishery.
Since data collection began in 1990, the abundance of adult female blue crabs has peaked three times: first in 1991 when abundance reached 227 million, second in 2010 when abundance reached 246 million and third in 2017 when abundance reached a record-high 254 million. Since female-specific regulations were implemented in 2008, the average adult female blue crab abundance has doubled from the previous decade. The adult female blue crab abundance has not fallen below the 70 million threshold since 2014.
Anthropogenic activity—including harvest pressure and development that leads to the loss of fish and shellfish habitat—can affect blue crab populations. Environmental factors—including winter temperatures, coastal currents, weather patterns and natural predation—can also affect blue crab abundance. Water quality improvements, underwater grass restoration and proper harvest management will be critical to maintaining this valuable resource
To achieve this outcome, Chesapeake Bay Program partners have committed to:
- Planning and implementing a benchmark stock assessment; and
- Continuing to support the Chesapeake Bay Stock Assessment Committee’s annual review of the status of the blue crab population.
Monitoring and assessing progress toward the outcome will occur through the Chesapeake Bay Stock Assessment Committee’s (CBSAC) annual review of blue crab survey data and determination of population status relative to biological reference points. The continuation of the annual Bay-wide Blue Crab Winter Dredge Survey will be essential in estimating the blue crab population and monitoring the stock.As part of the Chesapeake Bay Program's partnership-wide implementation of adaptive management, progress toward this outcome was reviewed and discussed by the Management Board in November of 2019.
Participating partners have committed to taking specific actions to achieve the approaches identified in the management strategy above.
Completed actions from this outcome's Logic & Action Plan include:
- In December 2018, the Sustainable Fisheries Goal Implementation Team determined that a benchmark blue crab stock assessment is not needed at this time. This decision was based on the fact that the recent stock assessment indicates the existing management framework is working.
The Sustainable Fisheries Goal Implementation Team leads the effort to achieve this outcome.
Participating partners include:
- Maryland Department of Natural Resources (State of Maryland)
- University of Maryland Center for Environmental Science Chesapeake Biological Laboratory (State of Maryland)
- Old Dominion University (Commonwealth of Virginia)
- Virginia Institute of Marine Science (Commonwealth of Virginia)
- Virginia Marine Resources Commission (Commonwealth of Virginia)
- Potomac River Fisheries Commission
- Chesapeake Bay Commission
- National Marine Fisheries Service (National Oceanic and Atmospheric Administration)
- University of North Florida
Maryland, Virginia and the District of Columbia also engage commercial and recreational blue crab harvesters through committees and advisory groups, which include the Maryland Blue Crab Industry Advisory Committee, Blue Crab Industry Design Team, Sport Fisheries Advisory Commission and Tidal Fisheries Advisory Commission; the Virginia Blue Crab Industry Panel and Marine Resources Commission Crab Management Advisory Committee; and the Potomac River Crab Advisory Committee.