Marine - Species


Blue Crab - Click to enlarge photo

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.

SC Marine Gamefish Tagging

Blue Crab (Callinectes sapidus Rathburn)

General Description
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 Size
Average carapace width: males – 5 1/2inches, females – 6 inches;
approx. maximum size: 10 inches;
maximum age: approx. 3 years

Habitat

Occupy a range of estuarine habitats as well as coastal bays, sounds and nearshore waters; often in association with submerged vegetation or oyster reefs.

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.

Reproductive Cycle

  • 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.

Foraging Habits

  • 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


Blue Crab Adundance in SC graphDNR surveys collected below average numbers of blue crab in 2012, similar to years before 2011. The population continues to fluctuate from low numbers seen during and after the long-term drought of 1998-2002. Recent drought conditions have continued to impact abundance and distribution, displacing crab further upriver. Data were derived from DNR's inshore crustacean survey and SCECAP projects. More information.

Fishery Status


Blue Crab Fishery in SC graphCommercial blue crab pot fishery landings continued to improve in 2012, approaching the long-term average. These two years reversed a decline that began in 2002, when landings were impacted by decade-long drought conditions and relatively low abundance. Periodic surveys of recreational crabbing indicate that it is important during the warmer months. Data presented in this graph were provided by DNR Fisheries Statistics Section.
More information
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Literature Cited

Archambault JA, EL Wenner, JD Whitaker. 1990. Life history and Abundance of Blue Crab, Callinectes sapidus Rathburn, at Charleston Harbor, South Carolina. Bull Mar Sci 46: 145-158.

Hines AH, RN Lipcius, AM Haddon. 1987. Population dynamics and habitat partitioning by size, sex, and molt stage of blue crabs Callinectes sapidus in a subestuary of central Chesapeake Bay. Mar Ecol Prog Ser 36: 55-64.

Laughlin RA. 1982. Feeding habits of the blue crab, Callinectes sapidus Rathbun, in the Apalachicola estuary, Florida. Bull Mar Sci 32: 807-822.

Low R, R Rhodes, ER Hens, D Theiling, E Wenner, D Whitaker. 1987. A profile of the blue crab and its fishery in South Carolina. Technical Report 66. Marine Resources Division, South Carolina Wildlife and Marine Resources Department, Charleston, SC. 21pp.

Mense DJ, EL Wenner. 1989. Distribution and abundance of early life history stages of the blue crab Callinectes sapidus, in tidal marsh creeks near Charleston, South Carolina. Estuaries 12: 157-168.

Millikin MR, AB Williams. 1984. Synopsis of biological data on the blue crab, Callinectes sapidus Rathbun. NOAA Technical Report NMFS 1, National Marine Fisheries Service, Washington DC. 39 pp.

Moore CJ. 1996. A field guide to the identification of marine species regulated in South Carolina coastal waters. Office of Fisheries Management, Marine Resources Division, South Carolina Wildlife and Marine Resources Department, Charleston, SC. 105 pp.

Perry HM, TD McIlwain. 1986. Species profiles: life histories and environmental requirements of coastal fishes and invertebrates (Gulf of Mexico) – blue crab. U.S. Fish Wild. Serv. Biol. Rep. 82 (11.55). U.S. Army Corp of Engineers, TR EL-82-4. 21pp. Available: http://www.nwrc.usgs.gov/wdb/pub/species_profiles/82_11-055.pdf. Accessed:September, 2009.

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. Available: http://www.nwrc.usgs.gov/wdb/pub/species_profiles/82_11-019.pdf. 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.