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Blue Crabs

Overview

There's nothing more “Chesapeake” than the Bay's signature crustacean, the blue crab. Callinectes (“beautiful swimmer”) sapidus (“savory”), a member of the swimming crab family, is an aggressive, bottom-dwelling predator and one of the most recognizable species in the Bay. The blue crab population is vulnerable to increased harvest pressure, as well as the effects of habitat loss due to poor water quality. Proper management of the crab harvest, as well as water quality improvements and bay grass restoration efforts, will help restore the Bay's blue crab population and maintain this valuable resource into the future.

Why are blue crabs important?

As both predator and prey, blue crabs are a keystone species in the Chesapeake Bay food web. Blue crabs also make up the most productive commercial and recreational fisheries in the Bay.

Blue crabs are an integral link in the Chesapeake Bay food web

Blue crabs serve as both predator and prey in the Bay's food web.

  • Blue crabs are prey for fish, birds — even other blue crabs! Soft-shelled crabs that have recently molted are especially vulnerable to predators.
  • Predatory fish like striped bass, as well as drums, eels, catfish, cownose rays and some sharks, rely on juvenile blue crabs as part of their diet.
  • Blue crab larvae are part of the planktonic community and are fed on by filter feeders such as oysters, menhaden, bay anchovies and juveniles of other fish species.
  • Bottom-dwelling blue crabs are among the chief consumers of the benthos. They feed on thin-shelled bivalves, other crustaceans, fish, marine worms, plants, detritus and nearly anything else they can find.
  • Blue crabs enhance salt marsh communities by feeding on marsh periwinkles.

Blue crabs are economically important

During the past 60 years, blue crabs — along with Atlantic menhaden — have dominated the Chesapeake Bay's commercial fisheries.

  • It is estimated that more than one-third of the nation's catch of blue crabs come from the Chesapeake Bay.
  • Blue crabs have the highest value of any Chesapeake Bay commercial fishery. The Bay's commercial blue crab harvest in 2000 was valued at approximately $55 million.
  • Blue crabs also support a major recreational fishery in the Bay.

How many blue crabs live in the Chesapeake Bay?

Chesapeake Bay scientists use the annual Bay-wide winter dredge survey as their main tool to estimate how many blue crabs are living in the Bay. According to the 2011 winter dredge survey, which took place just before the start of the 2011 commercial crab season, 461 million crabs are estimated to be living in the Chesapeake Bay.

The winter dredge survey also estimates the number of adult (age 1 or older) blue crabs in the Bay. In 2009, 223 million adult blue crabs were estimated to be living in the Bay. This is a 70 percent increase from 131 million adult crabs in 2008 and the first time since 1993 that adult blue crab abundance exceeded the interim goal of 200 million crabs. However, the number of juvenile (less than one year old) blue crabs was 179 million, still well below the historical average of 259 million juvenile crabs.

How is harvest a pressure on blue crabs?

It is estimated that more than one-third of the nation's blue crab catch comes from the Chesapeake Bay. Blue crabs—harvested as hard shell crabs, peeler crabs (just prior to molting) and soft shell crabs (immediately after molting)—have the highest value of any Chesapeake commercial fishery, bringing in more than $50 million per year. They also support a major recreational fishery in the Bay.

Between 1968 and 2005, commercial blue crab harvest from the Bay averaged around 73 million pounds annually. In several of those years, commercial harvests yielded over 100 million pounds of crabs; a record of 113 million pounds was set in 1993.

Since the early 1990s, there has been a dramatic decrease in Bay-wide blue crab landings. Commercial crabbers have also increased their fishing effort, but are catching fewer crabs per amount of effort than in years past. These occurrences likely relate to recruitment overfishing, when large removals of adults from the stock result in fewer juveniles being produced.

The 2007 Chesapeake blue crab harvest of 44.2 million pounds was among the lowest recorded since 1945. The low harvest corresponds with low stock abundance, but also reflects restrictive management measures in place since 2001 and 2002. While the crab harvest remains near record lows, the percentage of Bay crabs harvested remains high: an estimated 60 percent of the Bay's available blue crabs were caught in 2007—considerably more than the target harvest of 46 percent.

How is habitat loss a pressure on blue crabs?

Reduced acreage of underwater bay grasses due to poor water quality and irregular weather conditions has also been linked to the decline of blue crabs. Bay grass beds provide important habitat for blue crabs by protecting juveniles, molting adults and feeding adults from predators. Field experiments have shown that underwater bay grasses substantially reduce predation on juvenile blue crabs, and also result in higher growth rates compared to crabs living in unvegetated areas.

In addition to habitat loss, debate has grown over the effect of increased predation on the blue crab stock. Predatory fish like striped bass and Atlantic croaker—whose populations are currently very high—may rely on juvenile blue crabs as part of their diet, affecting the abundance of blue crab recruits (age 0 crabs).

How are blue crabs being restored?

Proper management of the crab harvest, as well as water quality improvements and underwater bay grass restoration efforts, will help restore the Bay's blue crab population and maintain this valuable resource into the future.

Blue crab management

Blue crabs are currently managed as a single species, using minimum catch size and seasonal limits on harvests to meet target levels of fishing pressure. The annual winter dredge survey determines if the blue crab stock's target levels have been exceeded. Under this strategy, fishing pressure is set to levels that should allow for increased abundance of crabs over time.

The Bay Program developed its first Chesapeake Bay Blue Crab Fishery Management Plan in 1989 to unify the approach of the three Bay jurisdictions that manage commercial crabbing: Maryland, Virginia and the Potomac River Fisheries Commission. A second fishery management plan for blue crab was implemented in 1997. Its goal was to manage blue crabs in a way that conserves the Bay-wide stock, protects its ecological value and optimizes the long-term use of the resource.

In 1996, the Bi-State Blue Crab Advisory Committee (BBCAC) was created through the Chesapeake Bay Commission to facilitate dialogue and coordinate blue crab fishery management among the same three Bay jurisdictions. The BBCAC is not regulatory; rather, it advises the governors, legislatures and resource managers in Maryland and Virginia of their findings and recommendations for blue crab management.

In 2001, the BBCAC recommended that the three jurisdictions take actions to double the spawning stock of blue crabs in the Bay. To meet this goal, the jurisdictions developed fishery management actions designed to decrease the annual blue crab harvest effort by 15 percent, with the intent of allowing the blue crab population to increase.

Protecting migrating blue crabs

In 2002, Virginia expanded their deep water blue crab sanctuary to 929 square miles off-limit to commercial crabbing. This area includes coastal ocean waters immediately adjacent to the mouth of the Bay, since blue crab larvae use this area as they grow into juveniles. The larger no-collection zone is estimated to reduce overall fishing pressure by about 6 percent.

Scientists are also working to better understand the life cycle and habits of blue crabs in the Bay. The Smithsonian Environmental Research Center (SERC) in Maryland uses tags to track crabs' movement and feeding habits. By researching crabs in their natural environment, Bay Program partners will be better able to manage the species and help sustain a thriving blue crab population for years to come.

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Chesapeake Bay News

In The Headlines


Blue Crab Abundance (Spawning-Age Females)

The abundance of spawning-age female blue crabs in the Chesapeake Bay increased to 147 million in 2013, compared with 97 million in 2012. This number is below the 215 million target but remains above the 70 million threshold.


Blue Crab Fishery Management

Based on 2012-2013 winter dredge survey data and estimates of Bay-wide harvest, the Chesapeake Bay spawning-age female blue crab population and harvest continued at sustainable levels. Harvest was estimated at 10 percent, well below the maximum number that can be taken (34 percent).



Publications

Adoption Statement - Blue Crab Fishery Management Plan, Amendment

Publication date: December 09, 2003 | Type of document: Adoption Statement | Download: Electronic Version

The adoption statement was to implement the management strategies and actions recommended by this amendment to protect blue crab spawning potential, reduce exploitation, increase our biological understanding of blue crabs through…

Blue Crabs and the Chesapeake Bay

Publication date: July 07, 2003 | Type of document: Fact Sheet | Download: Electronic Version

This fact sheet overviews blue crab anatomy, life cycle, habitat and current status of the Chesapeake Bay blue crab population

Blue Crab Fishery Management Plan

Publication date: May 01, 1998 | Type of document: Management Plan

Incorporates new information from the first Baywide stock assessment and recommends additional management strategies. Plan recommendations to protect the health of the blue crab stock which has the highest monetary value of any Bay…

Adoption Statement - Blue Crab Fishery Management Plan

Publication date: June 04, 1997 | Type of document: Adoption Statement

The 1997 Chesapeake Bay Blue Crab Fishery Management Plan is a guide to conserving and protecting the blue crab resource for long-term ecological, economic and social benefits

Blue Crab Fishery Management Plan (Report)

Publication date: June 01, 1997 | Type of document: Management Plan

The 1997 Chesapeake Bay Blue Crab Fishery Management Plan incorporates new information and management strategies into the 1989 fishery management plan.
 

Annual Progress Report: Fishery Management Plans 1994

Publication date: October 01, 1995 | Type of document: Management Plan | Download: Electronic Version

As part of the process of establishing accountability and tracking the implementation of management actions, each fishery management plan (FMP) is annually reviewed and updated. This report reviews the progress of management plans during…




From Around the Web

Bay FAQs

  • Do blue crabs put on weight before winter hibernation?
  • How long do blue crabs live?
  • What do blue crabs eat?

 

Bay Terms

  • Benthos
  • Bivalve
  • Crustaceans
  • Dredge
  • Keystone species
  • Predator
  • Prey
  • Submerged aquatic vegetation (SAV)

 

Bay-Friendly Tips

  • Avoid Bay Grass Beds
  • Steer clear of bay grass beds in shallow waters to avoid harming this critical habitat and food source.
  • Fertilize in the Fall
  • If you need to fertilize your lawn, do it in the fall. Spring rains wash fertilizer off lawns and into local waters.

 

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