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Blue Crabs

Overview

There is nothing more “Chesapeake” than the blue crab. The Bay’s signature crustacean is one of the most recognizable critters in the watershed, and supports commercial and recreational fisheries. But blue crabs are vulnerable to pollution, habitat loss and harvest pressure, and their abundance has fluctuated over time. Water quality improvements, underwater grass restoration and proper harvest management will help 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 support the most productive commercial and recreational fisheries in the Bay.

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

Blue crabs are both predators and prey in the Bay’s food web.

  • Blue crab larvae are part of the Bay’s planktonic community, and serve as food for menhaden, oysters and other filter feeders.
  • Juvenile and adult blue crabs serve as food for fish, birds and even other blue crabs. Striped bass, red drum, catfish and some sharks depend on blue crabs as part of their diet. Soft shell crabs that have just molted are particularly vulnerable to predators.
  • Blue crabs are among the top consumers of bottom-dwelling organisms, or benthos. Blue crabs are opportunistic feeders that eat thin-shelled bivalves, smaller crustaceans, freshly dead fish, plant and animal detritus, and almost anything else they can find.
  • Because blue crabs feed on marsh periwinkles, they help regulate periwinkle populations. Scientists are concerned that a drop in blue crab populations could harm salt marsh habitat, as periwinkle populations rise and the snails over-feed on marshgrass.

Blue crabs support the watershed economy

Over the past 60 years, blue crabs have dominated Chesapeake Bay fisheries.

  • It is estimated that more than one-third of the nation’s blue crab catch comes from the Bay.
  • Blue crabs support a large recreational fishery, and are the highest-valued commercial fishery in the Bay. The Bay’s commercial blue crab harvest was valued at approximately $55 million in 2000.

How many blue crabs live in the Chesapeake Bay?

Each year, scientists use the winter dredge survey to measure the Chesapeake Bay’s blue crab population. Maryland and Virginia scientists visit 1,500 sites over the course of three and a half months, using metal dredges to pull up and count crabs over-wintering in the mud. According to the results of the 2014 survey, 297 million blue crabs are estimated to be living in the Bay.

The Chesapeake Bay Program tracks the abundance of adult female blue crabs as an indicator of Bay health. In 2014, 68.5 million adult female crabs were estimated to be living in the Bay, compared with 147 million in 2013. According to a 2014 report from the Chesapeake Bay Stock Assessment Committee (CBSAC), the stock is depleted but overfishing is not occurring.

How does habitat loss affect blue crabs?

Blue crabs use underwater grass beds as nurseries and feeding grounds. A drop in underwater grass abundance—due to warming waters, irregular weather patterns and pollution—has been linked to the decline of blue crabs. Research has shown that grass beds protect crabs from predators and boost their growth rates. Research has also shown that denser grass beds hold more crabs, indicating both the quantity and quality of grass habitat can affect blue crab populations.

How does harvest pressure affect 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 and soft shell crabs—are the highest-valued commercial fishery in the Bay, and bring in millions of dollars each year. Blue crabs also support a recreational fishery in the region.

Since the 1990s, there has been a dramatic decline in blue crab landings, as watermen expend the same amount of effort to catch fewer crabs. This could be linked to “recruitment overfishing,” which occurs when large removals of adults result in fewer juveniles being produced.

According to a 2014 report from the Chesapeake Bay Stock Assessment Committee (CBSAC), 40.7 million pounds of blue crabs were harvested from the Bay and its tributaries during the 2013 crabbing season. Recreational harvest was estimated to be 3.9 million pounds, while commercial harvests from Maryland, Virginia and those waters managed by the Potomac River Fisheries Commission (PRFC) were estimated to be 36.8 million pounds. The total harvest was the lowest seen this century and well below the maximum number of blue crabs that can be taken from the Bay.

Because recreational and commercial harvests affect the blue crab population, CBSAC has named improving the harvest data a top research need.

How does predation affect blue crabs?

Debate has grown over the effect of predation on blue crab abundance. Striped bass, Atlantic croaker, red drum and other fish feed on juvenile blue crabs, and a change in these fish species’ populations could affect the abundance of blue crab “recruits,” or those crabs that are less than one year old.

How are blue crabs being protected?

Water quality improvements, underwater grass restoration and proper harvest management will help protect blue crab populations and maintain the resource into the future.

Blue crab management

Blue crabs are managed as a single species, using minimum catch size and seasonal harvest limits to meet target levels of fishing pressure. The annual winter dredge survey helps scientists determine whether the target blue crab harvest level has been met or exceeded. Under this strategy, target fishing pressure is set to a level that should allow for increased blue crab abundance over time.

The Chesapeake Bay Program developed its first Chesapeake Bay Blue Crab Fishery Management Plan in 1989 to promote collaboration among the three jurisdictions that manage commercial crabbing in the watershed: Maryland, Virginia and the Potomac River Fisheries Commission (PRFC). The Bay Program’s Chesapeake Bay Stock Assessment Committee (CBSAC) has continued to provide scientific advice to fisheries managers, and publishes a Blue Crab Advisory Report each year that offers advice on harvest regulations.

In response to prolonged low blue crab abundance, CBSAC recommended new management actions in 2011, including sex-specific management and a target abundance of 215 adult female blue crabs in the Bay.

Take Action

For Chesapeake Bay restoration to be a success, we all must do our part. Our everyday actions can have a big impact on the Bay. By making simple changes in our lives, each one of us can take part in restoring the Bay and its rivers for future generations to enjoy.

To protect blue crabs in the Bay watershed, consider protecting bay grasses. Boaters should follow posted speed limits and no-wake laws to avoid harming bay grass beds. Boaters can also steer clear of bay grasses growing in shallow waters.

Photos



 

Chesapeake Bay News

In The Headlines


Blue Crab Abundance (Spawning-Age Females)

The abundance of spawning-age female blue crabs in the Chesapeake Bay decreased to 68.5 million in 2014, compared with 147 million in 2013. This number is below both the 215 million target abundance and the 70 million threshold, which means spawning-age female crabs are currently in a depleted state. 


Blue Crab Fishery Management

Based on the results of the 2013 winter dredge survey and estimates of the 2013 Bay-wide harvest, the Chesapeake Bay spawning-age female blue crab population is in a depleted state, although harvest continued at sustainable levels. Harvest was estimated at 23 percent, just below the target (25.5 percent) and well below the maximum number that can be taken (34 percent).



Bay 101: Blue Crabs



June 21, 2011

Why are blue crabs important to the Chesapeake Bay? Bruce Vogt from the National Oceanic and Atmospheric Administration (NOAA) explains the iconic crustacean’s economic, ecologic and gastronomic value. Learn more about blue crabs in the Chesapeake Bay Program’s online Field Guide.

Produced by Matt Rath
Music: “A Moment of Jazz” by Ancelin

From the Field: Winter dredge survey counts Chesapeake Bay crabs



April 24, 2013

April 2013: The Chesapeake Bay winter dredge survey is an annual count of the Bay’s blue crab population, and a critical component of blue crab management. The information gathered on abundance, young-of-the-year and spawning stock—those crabs that will mature enough to reproduce during the upcoming year—allows fisheries managers to set commercial and recreational harvest limits for the season ahead.
Closed captions: http://www.youtube.com/watch?v=28mvEE7ydXA

Produced by Steve Droter
Music: “Elle Aime Ca” by Löhstana David


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

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

 

Bay Terms

  • Abundance index
  • Benthos
  • Crustaceans
  • Dredge
  • Food chain/web
  • Keystone species
  • Overwinter
  • 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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