Species:

Callinectes sapidus

Common Names:

Blue Crab, Atlantic blue crab, male crab called a jimmy or channeler, mature female called a sook, young female called a sally crab, or she crab, mature female carrying brood of eggs called a sponger or sponge crab

Family

Portunidae

Order:

Decapoda

Description:

has 10 legs, last pair of legs paddle shaped.  Shell more than twice as wide as long with 9 marginal teeth (9th a strong spine).  Usually olive or bluish green above, claws bright blue below; young are paler.  Male abdomen abruptly tapered,  female's broadly rounded. Up to 9 inches wide between tips of longest spines.

Fishery Status:

• Value

• Annual Harvest

• National Commercial Landings Data Searchable By Species And Year
• Virginia Commercial Landings Data:
• Maryland Commercial Landing Data

Predators:

Predators of blue crabs include fish as well as other blue crabs. The major fish predators of blue crabs in both their postlarval and juvenile stages  include the Black Drum, Red Drum, the American Eel, Striped Bass, Spot, Sea Trout catfish and the Atlantic Croaker. Some sharks and cownose rays feed on juveniles and larger crabs. The Atlantic Ridley sea turtle, an endangered species, migrates to the Bay every summer to find its preferred food, the blue crab. 

Prey/Food source:

Blue crabs are classified as general scavengers, bottom carnivores, detritivores, and omnivores.
Adult blue crabs prefer mollusks such as oysters and hard clams as their primary food sources.  Some other common food items include dead and live fish, crabs (including other blue crabs), shrimp, benthic macroinvertebrates, organic debris, and aquatic plants and associated fauna such as roots, shoots and leaves of sea lettuce, eelgrass, ditch grass, and salt marsh grass. It will also prey on oyster spat, newly set oysters and clams, or young oysters and quahogs if other food is unavailable.
Juvenile  blue crabs feed mostly on benthic macroinvertebrates, small fish, dead organisms, aquatic vegetation and associated fauna.
Larva crabs called Zoeae are phytoplanktivorous and readily consume algae, phytoplankton and zooplankton. Megalope are considered general scavengers, bottom carnivores, detritivores, and omnivores. Megalope are more omnivorous than zoeae and prey upon fish larvae, small shellfish, and aquatic plants.

Life History:

• In the Chesapeake Bay, blue crab larvae–called zoea–are released by mature females in high salinity waters near the mouth of the Bay. The zoea are transported to the continental shelf, where they develop for a period of 30 to 45 days, through seven or eight distinct stages. The shrimplike zoea feed on zooplankton and plant material.
• Zoea change to the postlarval–megalopae–stage on the near-shore Atlantic shelf.
• Once they have been swept into the Bay by wind and currents, megalopae migrate vertically in response to light and tide. They use nocturnal flood tides to assist their movement up the estuary to shallow estuarine nursery habitats.
• Megalopae settle in the lower Bay and use SAV beds as nursery beds.  After six to 20 days (and depending on salinity and temperature), the megalopae molt producing the true first crab stage.  It is at this time that they become recognizable as miniature blue crabs.  
• Blue crabs mature at approximately 12 to18 months of age. Under current levels of fishing pressure, most crabs live from one to two years beyond maturity and the typical lifespan of a crab is up to three years. The maximum age may be as long as five to eight years.
• The sexually mature crab is approximately five inches wide–the legal size for harvesting.
• Before mating, the male "cradles" the female in its legs and carries her for up to several days while searching for suitable cover, where he guards her during her final molt. Mating takes place while the female is in her soft-shell phase. After mating, the male resumes cradling the female for several more days until the new shell has hardened. The male departs to search for another receptive female; the female migrates to the higher salinities of the lower Bay, where she develops an orange external egg mass beneath her apron that may contain between 750,000 and 8 million eggs, depending on her size.
• The egg mass darkens over a two-week period as the orange yolk is consumed by the developing larvae. Larvae develop large black eye spots as hatching approaches.
• Spawning is protracted and occurs over a period of one to two weeks. Spawning occurs from May to September, with a minor peak in June and major peaks in July and August.
• Individual females may spawn more than once, depending on the amount of sperm transferred during mating.
• Successive spawns may occur during the same year, or females may overwinter before spawning again the following spring.

Habitat & Range:

• Range:  Cape Cod to Uruguay, sometimes north to Massachusetts Bay.  Offshore to at least 120 feet but especially common in estuaries and ranges into fresh water.
• Immediately after molting, crabs are vulnerable to predators because they are soft, so they often hide in Bay grass beds for protection. Young crabs use Bay grass beds for nursery areas, and crabs of all sizes forage for food there. Bay scientists have found that 30 times more young crabs were found in Bay grasses than in areas without grass.
• Male crabs prefer lower salinity areas in the upper Bay and tributaries. Females prefer the higher salinity of the lower Bay and the mid to lower tributaries, and many overwinter in southern Bay waters.

Main Reference:

The Blue Crab Archives,