Amendment #1
1997 Chesapeake Bay Blue Crab Fishery Management Plan
February 2003
Introduction
A unified management approach among the Bay jurisdictions was initiated with the
development of the 1989 Chesapeake Bay Blue Crab Fishery Management Plan (FMP). The
1989 FMP recognized the importance of the blue crab resource, identified areas of concern, and
recommended strategies to stabilize fishing effort. In 1997, the plan was completely revised to
incorporate new information and management strategies. Major recommendations include: 1)
restore and protect blue crab habitat and water quality: 2) stabilize the fishery; 3) limit access to
the fishery and lower the cost of harvesting crabs; 4) prevent an increase in exploitation; 5)
design and implement a survey to estimate recreational catch and effort; 6) monitor the
commercial fishery; 7) improve enforcement of regulations; and 8) develop socioeconomic data
collection to assess the social and economic utilization of the blue crab resource. In order to
provide long-term protection for the blue crab stock, the plan set forth several strategies and
actions that required reevaluation after several years. Strategy 1.1 initiated the development of
"references for evaluating stock status and implementing fisheries or habitat management
measures." The strategy also stated that "targets" would be defined as "safe management levels"
and "limits" would be "maximum limits for sustainability."
Several actions were delineated to address the strategy. First, the 1997 Baywide stock
assessment (Rugolo et al) was scheduled to be updated in 1999 and every five years thereafter.
The stock assessment would be used as a tool to determine the status of the blue crab population.
In addition, new assessment tools would be considered, if available. The Chesapeake Bay Stock
Assessment Committee (CBSAC), established in 1985 by the National Marine Fisheries Service
(NMFS) with support of the NOAA Chesapeake Bay Office, has supported the funding of several
important research projects that contribute to updating the stock assessment. After the 1997 Blue
Crab FMP was adopted, it became apparent that the stock assessment should be updated annually
and not every fifth year. The CBSAC Technical Workgroup was tasked with updating the stock
assessment and since 1998, has prepared an annual Blue Crab Advisory Report.
The second action under the strategy for protecting the blue crab stock was a blue crab
target setting effort to examine how environmental variables affect stock size and recruitment; to
examine blue crab harvest and abundance by life history stage, time and area; and, to develop a
regional model to predict life stages and regions of greatest sensitivity of blue crab to changes in
exploitation patterns and rates. This effort resulted in the preparation of a "Blue Crab Target
Setting Final Report" ( Miller and Houde 1998). The report concluded that fishing effort was
"higher than is desirable to maintain a high-quality fishery in perpetuity;" fishing mortality (F)
should be stabilized and reduced; and that the blue crab stock was "growth overfished." The
report recommended an overall reduction in F by at least 30%; continued monitoring of the blue
crab resource; and additional information on the effects of the recreational fishery.
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The third action to meet the strategy for protecting the blue crab stock was to convene a
special Bi-State Blue Crab Advisory Committee (BBCAC) under the Chesapeake Bay
Commission to review the status of the blue crab resource and the effectiveness of regulations.
The BBCAC consists of a joint panel of legislators; representatives from the blue crab industry,
commercial and recreational fisheries; representatives from Maryland, Virginia, and the Potomac
River Fisheries Commission; and, other interest groups. In addition, a technical workgroup
(TWG) was formed comprised of researchers, resource managers, resource economists and other
experts to advise on a number of technical issues. The fourth action tasked the TWG with an
economic assessment of various biologically-determined limits and target levels. The TWG was
also tasked with assessing the economic ramifications of policies designed to stabilize harvest
and effort levels. Since its original conception in 1999, the roles of the BBCAC and TWG have
expanded.
After a two-year analysis of the blue crab resource and how it is managed, the BBCAC
completed an action plan (BBCAC 2001) and the following recommendations were made:
1)	adopt a threshold and target for the blue crab resource;
2)	reduce fishing effort through a phased approach to reach the adopted target;
3)	ensure that reductions in effort are fairly distributed among all user groups; and,
4)	analyze multispecies interactions and habitat interactions.
Although using biological reference points for managing the blue crab resource began in
January 2001, this amendment formally adopts fishery management thresholds and targets for the
blue crab resource in Chesapeake Bay. The amendment reaffirms the strategy to reduce fishing
effort and recognizes the importance of monitoring, habitat protection and ecosystem processes.
Stock Status
Data analyses indicate that blue crab abundance is below average and has declined in
recent years (CBSAC TC 2002). Length-based estimates of fishing mortality (F) indicate the
stock is fully exploited. The 2001 Chesapeake Bay commercial harvest was approximately 52
million pounds and is 30.6% below the 1968-2001 average of 75 million pounds. Megalopae
abundance has declined at the mouth of the Bay since the Chesapeake Bay Program Zooplankton
Monitoring Program began in 1985. Recruitment indices are contradictory. Maryland and
Virginia trawl surveys indicate average recruitment but the baywide winter dredge survey
indicates below average recruitment. Based on the data from the three surveys, there is a
declining trend in recruitment in recent years. There is consensus among biologists and members
of the BBCAC to adopt biological reference points (BRPs) or targets and thresholds for
managing the blue crab resource and develop rules for implementing management actions.
Stock Status Strategy
The Bay jurisdictions will adopt appropriate biological reference points for managing the
blue crab resource and control rules for implementing management actions. The BRPs are
expected to change over time as new data becomes available and the stock is reassessed.
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Thresholds and targets will be updated according to new assessments and decision rules
will be developed to manage the resource, i.e., delineate actions to be taken if the BRPs
are under achieved, achieved or exceeded.
Action 1
The jurisdictions will adopt a threshold fishing mortality rate that preserves 10%
of the blue crab spawning potential relative to an unfished stock and a minimum
stock size threshold.
Action 2
The jurisdictions will adopt a target fishing mortality rate of F20 which if achieved,
will increase the blue crab spawning potential from 10% to 20% relative to that of
an unfished stock.
Action 3.
The jurisdictions will develop control rules based on the BRPs for managing the
blue crab resource.
Action 4.
The Bay jurisdictions will utilize the results of fishery-independent surveys to
determine stock status. Currently, five surveys are utilized to determine stock
status and include the Virginia trawl survey, the Maryland summer trawl survey,
the Calvert Cliffs crab pot survey, the Baywide winter dredge survey and the
Baywide zooplankton monitoring.
Fishing Effort
Based on the current assessment of the stock, the trend in fishing mortality rates (F) is
unclear. Length-based estimates suggest F may be declining while estimates of abundance
suggest exploitation is increasing. The methodology used to estimate F needs to be refined.
Spawning stock abundance has declined since the early 1990s. The 2000 and 2001 abundance
estimates were the lowest in the time series. The average exploitable abundance of age 1+ crabs
is below average. Since blue crab recruitment is highly variable from year to year and has
exhibited a declining trend over the last few years, the blue crab resource is believed to be at risk
of overexploitation.
Fishing Effort Strategy
The Bay jurisdictions will adjust fishing effort to achieve the adopted BRPs.
Action 5.
The Bay jurisdictions will reduce the exploitation rate of legal-sized blue crabs to
meet the target BRP. Methods to achieve this objective may include a
combination of time limits, seasons, gear restrictions, catch limits, size limits,
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limited entry and/or other methods as necessary and appropriate.
Monitoring
Biological, environmental and fishery data are needed in order to successfully manage the
blue crab resource and assess blue crab stock status. The 2002 Blue Crab Advisory Report
identified the following baywide information needs: 1) harvest and effort data from the
commercial and recreational fisheries; 2) growth and mortality rates; and, 4) the age, size, sex
and maturity composition of the harvest and stock. Environmental effects on the blue crab
resource, especially during the early larval stages that occur outside of the Bay, are important to
understanding and possibly predicting annual recruitment to the stock. Blue crab play an
important role in the food web of the Chesapeake Bay. They are an important prey item for a
variety of fish and other predators in the Bay. Their role as prey should be considered in
managing the blue crab resource from an ecosystem perspective.
Monitoring Strategy
The Bay jurisdictions will collect fishery-dependent and fishery-independent data on the
blue crab resource and where possible, increase the biological understanding of its role in
the food web of the Bay.
Action 6
The Bay jurisdictions will continue to monitor the blue crab resource in the Bay
and work towards developing a baywide monitoring approach.
Habitat
In response to reduced abundance in the blue crab stock and increased fishing pressure on
the
resource, Virginia designated areas that are closed to blue crab harvest. Virginia established the
Hampton Roads and Bayside Eastern Shore Blue Crab Management Areas and implemented
provisions to control the harvest of crabs from these areas. The Hampton Roads Blue Crab
Management Area consists of all tidal waters inshore and upstream of a line formed by the
extreme south and north ends of the westbound span of the Hampton Roads Bridge Tunnel.
Virginia also established the Virginia Blue Crab Sanctuary (2002) which protects 927 square
miles from harvest, June 1st through September 15th. No commercial or recreational crabbing is
allowed from the sanctuary which includes waters 30 feet deep or greater.
Habitat Strategy
The Bay jurisdictions will identify and protect critical blue crab habitat.
Action 7
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Maryland and Virginia will consider designating additional sanctuary areas to
protect blue crab habitat based on new research data.
Action 8
The jurisdictions will continue to protect submerged aquatic vegetation (SAV) in
potential post-larval settlement areas.
Ecosystem
Blue crabs play an important role in the food web of the Bay. They are prey for a variety
of finfish including striped bass, weakfish, bluefish, and black drum. Although they are
opportunistic and generalists in their food habits, they are a major predator on a number of
molluscs including oysters and soft clams. There are a number of studies in progress to define
blue crab trophic interactions.
There is concern about blue crabs and their interactions with three species of non-native
crabs specifically, the green crab (Carcinus maenas), the Japanese shore crab (Hemigrapsus
sanguineus) and the Chinese mitten crab (Eriocheir sinensis)). These non-native species have
been identified as potential threats to the blue crab population in terms of habitat and trophic
interactions. Currently, the green crab and Japanese shore crab have been detected in Maryland's
coastal waters and in the lower Chesapeake Bay.
Ecosystem Strategy
The jurisdictions will incorporate information on ecosystem processes relating to blue
crabs as it becomes available and utilize the information to determine management
actions as necessary. Precautionary management that considers ecosystem services
provided by the blue crab should be adopted.
Action 9
As data becomes available on food web dynamics, adjust fishing mortality rates
on the blue crab population to include predator needs.
Action 10
Evaluate the impact of non-native crab introductions on the blue crab population
and develop recommendations accordingly.
Conclusion
The goal and objectives of the 1997 Chesapeake Bay Blue Crab Fishery Management
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Plan continue to be appropriate for managing the blue crab resource in the Bay. Each year as
more biological monitoring data becomes available for stock assessment analyzes, the ability to
develop management strategies and actions improves. The most recent stock assessment
indicates that recruitment is declining, there is a low female spawning stock size, and the
exploitable stock size is also low.
References
Bi-State Blue Crab Advisory Committee (BBCAC). 2001. Taking Action for the Blue Crab:
Managing and Protecting the Stock and its Fisheries. Chesapeake Bay Commission, Annapolis,
Maryland.
Chesapeake Bay Stock Assessment Committee's Technical Subcommitee (CBSAC TC). 2002.
The 2001 Chesapeake Bay Blue Crab Advisory Report. NOAA Chesapeake Bay Program Office,
Annapolis, MD.
Miller, T.J. and E.D. Houde. 1998. Blue Crab Target Setting Final Report. University of
Maryland Center for Environmental Science, Chesapeake Biological Laboratory, Solomons, MD
Ref. No. [UMCES]CBL 98-129.
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