Marine - Species
SC Species Regulations for Blue Crab
Saltwater Fishing License required.
5 inch minimum carapace width; no bag limit in state waters; limit of two traps (pots) per person (Commercial Saltwater Fishing License, Vessel Decal, and Gear License required to fish more than two pots); females with egg mass (sponge) must be immediately released unharmed.
Blue Crab (Callinectes sapidus Rathburn)
Smooth oblong carapace in variations of gray, blue, or brownish green. Four spines on the anterior edge of the carapace, 9 spines on the anterior lateral edge (posterior-most are the largest). Males: T-shaped abdomen, blue on legs and inner surface of chelipeds, blue fingers of claws. Females: triangular (immature) or circular (mature) abdomen, fingers of claws are orange with purple tips.
Average carapace width: males – 5 1/2inches, females – 6 inches;
approx. maximum size: 10 inches;
maximum age: approx. 3 years
Adults: Males utilize soft bottom tidal creeks and middle to upper reaches of estuaries, generally moving further upstream than females. Females utilize similar but higher salinity habitats until moving to estuary mouths to spawn; thereafter, females remain near inlets or in coastal ocean waters.
Juveniles: Reside in shallow, soft bottom habitats in upper estuaries, tidal creeks, salt marshes, and rivers.
- Adults mature by 1 – 2 years of age; approx. size at maturity: males – 4 inches, females – 5 inches.
- Mating occurs in low salinity upper estuary waters following terminal molting of females. Mating occurs February – November. Females mate only once in life, store sperm internally, and spawn (April-August) multiple times over the next 1 – 2 years.
- Early larval development (zoeal stages) occurs in oceanic waters. Larvae use tidal currents to recruit to estuaries as megalopae (i.e. postlarvae) and move into upper estuaries as juveniles.
- All sizes of blue crab are opportunistic omnivores and forage along the bottom; overall diet is similar between adults and juveniles; preferred prey may change with size and locality.
- Adults: Feed primarily on bivalves, snails, shrimp, fishes, and decaying organic matter; also cannibalize other blue crabs.
- Juveniles: Consume small bivalves, detritus, and plant matter. Larvae feed on zooplankton.
Availability/Vulnerability to Harvest
- Adults and juveniles are present in South Carolina estuaries year-round; overwintering typically occurs in estuaries, but crabs may seek deeper water, become sluggish, and bury in mud during cold; movement to deeper water can also occur with extremely warm water.
- Salinity significantly influences distribution of various life stages; juveniles and adult males seemingly prefer lower salinity waters than female crabs. Larval and megalopae development is best at salinities ≥ 20 ppt.
- Conservation concerns: degradation and loss of estuarine habitats; protection of coastal ocean habitat critical to larval development; viral and bacterial prevalence and mortality; potential for high commercial and recreational harvest; mortality associated with abandoned crab pots; gray crab disease (caused by the pathogenic amoeba Paramoeba perniciosa).
Abundance of Species
DNR surveys collected low numbers of blue crabs in 2013, similar to numbers observed in 2007-2010. The population continues to be in an apparent decline, begun during and after the long-term drought of 1998-2002. Although significantly more rainfall occurred in 2013, overall numbers of blue crab have not recovered in recent years, due possibly to changing climatic conditions and fishing pressure. Data used in the associated graph were derived from DNR's inshore crustacean survey and SCECAP projects. More information.
Commercial blue crab pot fishery landings since 2011 have steadily been above the long term 10 year average, with 2013 recording slightly lower landings than 2012. Previous landings were impacted by decade-long drought conditions and relatively low abundance. Periodic surveys of recreational crabbing indicate that rainfall, or the lack thereof, is important during the warmer months. Data presented in this graph were provided by DNR Fisheries Statistics Section.
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Laughlin RA. 1982. Feeding habits of the blue crab, Callinectes sapidus Rathbun, in the Apalachicola estuary, Florida. Bull Mar Sci 32: 807-822.
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Van Den Avyle MJ. 1984. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (South Atlantic) – blue crab. U.S. Fish Wildl Serv FWS/OBS-82/11.19. U.S. Army Corps of Engineers, TR EL-82-4. 16 pp. Accessed: September, 2009.
Whitaker JD, LB Delancey, JE Jenkins, MB Maddox. 1998. A review of the fishery and biology of the blue crab, Callinectes sapidus, in South Carolina. J Shellfish Res 17: 459-463.