Callinectes sapidus (from the Greek calli- = "beautiful", nectes = "swimmer", and Latin sapidus = "savory"), the blue crab, Atlantic blue crab, or regionally as the Chesapeake blue crab, is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and introduced internationally.
C. sapidus is of significant culinary and economic importance in the United States, particularly in Louisiana, the Chesapeake Bay, and New Jersey. It is the Maryland state crustacean and is the state's largest commercial fishery.
Callinectes sapidus is a decapod crab of the swimming crab family Portunidae. The genus Callinectes is distinguished from other portunid crabs by the lack of an internal spine on the carpus (the middle segment of the claw), as well as by the T-shape of the male abdomen. Blue crabs may grow to a carapace width of 230 mm (9.1 in). C. sapidus individuals exhibit sexual dimorphism. Males and females are easily distinguished by the shape of the abdomen (known as the "apron") and by color differences in the chelipeds, or claws. The abdomen is long and slender in males, but wide and rounded in mature females. A popular mnemonic is that the male's apron is shaped like the Washington Monument, while the mature female's resembles the dome of the United States Capitol. Claw color differences are more subtle than apron shape. The immovable, fixed finger of the claws in males is blue with red tips, while females have orange coloration with purple tips. A female's abdomen changes as it matures: an immature female has a triangular-shaped abdomen, whereas a mature female's is rounded.
Other species of Callinectes may be easily confused with C. sapidus because of overlapping ranges and similar morphology. One species is the lesser blue crab (C. similis). It is found further offshore than the common blue crab, and has a smoother granulated carapace. Males of the lesser blue crab also have mottled white coloration on the swimming legs, and females have areas of violet coloration on the internal surfaces of the claws. C. sapidus can be distinguished from another related species found within its range, C. ornatus, by number of frontal teeth on the carapace. C. sapidus has four, while C. ornatus has six.
The crab's blue hue stems from a number of pigments in the shell, including alpha-crustacyanin, which interacts with a red pigment, astaxanthin, to form a greenish-blue coloration. When the crab is cooked, the alpha-crustacyanin breaks down, leaving only the astaxanthin, which turns the crab to a red-orange or a hot pink color.
Callinectes sapidus is native to the western edge of the Atlantic Ocean from Cape Cod to Argentina and around the entire coast of the Gulf of Mexico. It has recently been reported north of Cape Cod in the Gulf of Maine, potentially representing a range expansion due to climate change. It has been introduced (via ballast water) to Japanese and European waters, and has been observed in the Baltic, North, Mediterranean and Black Seas. The first record from European waters was made in 1901 at Rochefort, France. In some parts of its introduced range, C. sapidus has become the subject of crab fishery, including in Greece, where the local population may be decreasing as a result of overfishing.
The natural predators of C. sapidus include eels, drum, striped bass, spot, trout, some sharks, humans, and cownose sting rays. C. sapidus is an omnivore, eating both plants and animals. C. sapidus typically consumes thin-shelled bivalves, annelids, small fish, plants and nearly any other item it can find, including carrion, other C. sapidus individuals, and animal waste. C. sapidus may be able to control populations of the invasive green crab, Carcinus maenas; numbers of the two species are negatively correlated, and C. maenas is not found in the Chesapeake Bay, where C. sapidus is most frequent.
Callinectes sapidus is subject to a number of diseases and parasites. They include a number of viruses, bacteria, microsporidians, ciliates, and others. The nemertean worm Carcinonemertes carcinophila commonly parasitizes C. sapidus, especially females and older crabs, although it has little adverse effect on the crab. A trematode that parasitizes C. sapidus is itself targeted by the hyperparasite Urosporidium crescens. The most harmful parasites may be the microsporidian Ameson michaelis, the amoeba Paramoeba perniciosa and the dinoflagellate Hematodinium perezi, which causes "bitter crab disease".
In the Chesapeake Bay, C. sapidus undergoes a seasonal migration of up to several hundred miles. Female blue crabs mate only once in their lifetimes. After mating, the female crab travels to the southern portion of the Chesapeake, using ebb tide transport to migrate from areas of low salinity to areas of high salinity. fertilizing her eggs with sperm stored during her single mating months or almost a year before. Up to two million eggs may be produced in a single brood, and a single female can produce over 8,000,000 eggs in her lifetime. After brooding the eggs as an orange mass on her pleopods for around two weeks, the female crab releases her eggs in November or December. The crabs hatch into larvae and float in the mouth of the bay for four to five weeks, after which the juvenile crabs make their way back into the bay.
Range of Fisheries
Fisheries for C. sapidus exist along much of the Atlantic coast of the United States, and in the Gulf of Mexico. Although the fishery has been historically centered on the Chesapeake Bay, contributions from other localities are increasing in volume. In 2002, around two-thirds of the total U.S. market of C. sapidus came from four states – Louisiana (22%), North Carolina (17%), Maryland (14%), and Virginia (13%). No other state contributed more than 3%, with 17% of the market being supplied by imports, especially from Indonesia (6% of the total U.S. market) and Thailand (4%); no data are available on the amounts exported from the U.S.
Louisiana has the world's largest blue crab fishery. The industry was not commercialized for interstate commerce until the 1990s, when supply markedly decreased in Maryland due to problems in Chesapeake Bay. Since then, Louisiana has steadily increased its harvest. In 2002, Louisiana harvested 22% of the nation's blue crab. That number rose to 26% by 2009 and 28% by 2012. The vast majority of Louisiana crabs are shipped to Maryland, where they are sold as "Chesapeake" or "Maryland" crab.
Chesapeake Bay Fishery
The Chesapeake Bay, located in Maryland and Virginia, is famous for its blue crabs. The crab harvest constitutes the most important economic fishery for both states. In 1993, the combined harvest of C. sapidus was valued at around US$100 million. Over the years, the population of C. sapidus has dropped, and the amount captured has fallen from over 125,000 t (276,000,000 lb) in 1993 to 81,000 t (179,000,000 lb) in 2008.
In the Chesapeake Bay, the population fell from 900 million to around 300 million, and capture fell from 52,000 t (115,000,000 lb) in the mid-1990s to 28,000 t (62,000,000 lb) in 2004, with revenue falling further, from $72 million to $61 million.
Many types of gear have been used to catch blue crabs along the Atlantic and Gulf Coasts. Initially people used very simple techniques and gear, which included hand lines, dip nets, and push nets among a variety of other gear types. The trotline, a long baited twine set in waters 5–15 feet deep, was the first major gear type used commercially to target hard crabs. Use of commercial trotlines is now mostly limited to the tributaries of the Chesapeake Bay. In the Gulf of Mexico, trotline use drastically declined after invention of the crab pot in 1938. Crab pots are rigid boxlike traps made of hexagonal or square wire mesh. They possess between two and four funnels that extend into the trap, with the smaller end of the funnel inside of the trap. A central compartment made of smaller wire mesh holds bait. Crabs attracted by odorant plumes from the bait, often an oily fish, enter the trap through the funnels and cannot escape.
Efforts to Manage Fisheries
Because of its commercial and environmental value, C. sapidus is the subject of management plans over much of its range. In 2012, the C. sapidus population in Louisiana was recognized as a certified sustainable fishery by the Marine Stewardship Council.
- Beautiful Swimmers – a Pulitzer Prize-winning book with an extensive discussion of the crabs and their life cycle
- Chesapeake - a novel by James Michener with a story about C. sapidus titled "Jimmy the crab".
- Crab cake
- She-crab soup
- Soft-shell crab
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- Michelle Sempsrott (March 8, 2011). "Florida's Commercial Blue Crab (Callinectes sapidus) Fishery: Managing Harvest with Output Control" (PDF). Oregon State University. Capstone Project – FW 506.
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- "Number of blue brabs in Bay remains below long-term average". National Oceanic and Atmospheric Administration. July 28, 2008.
- Yonathan Zohar, Anson H. Hines, Oded Zmora, Eric G. Johnson, Romuald N. Lipcius, Rochelle D. Seitz, David B. Eggleston, Allen R. Place, Eric J. Schott, John D. Stubblefield & J. Sook Chung (2008). "The Chesapeake Bay blue crab (Callinectes sapidus): a multidisciplinary approach to responsible stock replenishment". Reviews in Fisheries Science 16 (1): 24–34. doi:10.1080/10641260701681623.
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- Benjamin Alexander-Bloch (March 19, 2012). "Louisiana blue crab earns a blue ribbon". The Times-Picayune. Retrieved March 19, 2012.
|External identifiers for Callinectes sapidus|
|Encyclopedia of Life||312939|
|Also found in: Wikispecies|
- Media related to Callinectes sapidus at Wikimedia Commons
- Female Blue Crab Anatomy - Callinectes sapidus - Dana Point Fish Company
- Crab diagram
- Blue crab life cycle
- The Maryland Blue Crab
- Boy crabs boogie to bring females out of hiding – the wild dance of male blue crabs propels a jet of pheromones to attract would-be lovers, New Scientist, 7 April 2008
- Chesapeake watermen fear blue crab not coming back – Associated Press, July 16, 2008