Callinectes sapidus (from the Greek calli- = "beautiful", nectes = "swimmer", and Latin sapidus = "savory"), the Chesapeake or Atlantic blue crab, is a crustacean found in the waters of the western Atlantic Ocean, the Pacific coast of Central America and the Gulf of Mexico. On the Pacific coast of Central America it is largely ignored as a food source as picking the meat is considered too difficult. It is the Maryland state crustacean and the subject of an extensive fishery.
The blue crab is native to the western edge of the Atlantic Ocean from Nova Scotia to Argentina and around the entire coast of the Gulf of Mexico. It has been introduced (via ballast water) to Japanese and European waters, and has been observed in the Baltic Sea, North Sea, Mediterranean Sea and Black Sea.
The natural predators of the blue crab include eels, drum, striped bass, spot, trout, some sharks, humans, and cownose sting rays. The blue crab is an omnivore, eating both plants and animals. Blue crabs typically consume thin-shelled bivalves, annelids, small fish, plants and nearly any other item they can find, including carrion, other blue crabs and animal waste.
Blue crabs 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 blue crabs are most frequent.
The blue crab may grow to a carapace width of 230 mm (9.1 in). It can be distinguished from a related species that occurs in the same area by the number of frontal teeth on the carapace; C. sapidus has four, while C. ornatus has six.
Male and female blue crabs can be distinguished by their abdomens, which are long and slender in males, but wide and rounded in mature females. A female's abdomen changes as it matures: an immature female has a triangular shaped abdomen, whereas a mature female's is rounded.
The 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 red-orange.
Chesapeake Bay blue crabs undergo a seasonal migration; after mating, the female crab travels to the southern portion of the Chesapeake, fertilizing her eggs with sperm stored from her only mating months or almost a year before. In November or December, the female crab releases her eggs. The crabs hatch in a larval form and float in the mouth of the bay for four to five weeks, then the juvenile crabs make their way back into the bay.
Commercial importance in the United States
The Chesapeake Bay, located in Maryland and Virginia, is famous for its blue crabs, and they are one of the most important economic items harvested from it. In 1993, the combined harvest of the blue crabs was valued at around US$100 million. Over the years the population of the blue crab has dropped, and the amount captured has fallen from over 125,000 t (280,000,000 lb) in 1993 to 81,000 t (180,000,000 lb) in 2008. In the Chesapeake Bay, the population fell from 900 million to around 300 million, and capture fell from 52,000 t (110,000,000 lb) in the mid 1990s to 28,000 t (62,000,000 lb) in 2004, with revenue falling from $72 million to $61 million.
Because of their commercial and environmental value, blue crabs are the subject of management plans over much of their range. In 2012, the blue crab 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.
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- "Callinectes sapidus". Smithsonian Marine Station at Fort Pierce. October 11, 2004. http://www.sms.si.edu/IRLSpec/Callin_sapidu.htm.
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- "Callinectes sapidus". CIESM: The Mediterranean Marine Research Network. August 2006. http://www.ciesm.org/atlas/Callinectessapidus.html.
- "Blue Crab-About The bay". The Chesapeake Bay Foundation. http://www.chesapeakebay.net/blue_crab.htm.
- Catherine E. DeRivera, Gregory M. Ruiz, Anson H. Hines & Paul Jivoff (2005). "Biotic resistance to invasion: Native predator limits abundance and distribution of an introduced crab" (PDF). Ecology 86 (12): 3367–3376. doi:10.1890/05-0479. http://serc.si.edu/labs/marine_invasions/publications/PDF/DeRivera_et_al_%202005%20_Biotic_%20resistance_to_Green_Crab.pdf.
- Susan B. Rothschild (2004). "Sandy beaches". Beachcomber's Guide to Gulf Coast Marine Life: Texas, Louisiana, Mississippi, Alabama, and Florida (3rd ed.). Taylor Trade Publications. pp. 21–38. ISBN 978-1-58979-061-2. http://books.google.co.uk/books?id=w0hWmtbRNwIC&pg=PA34.
- "Blue crab, Callinectes sapidus". Maryland Fish Facts. Maryland Department of Natural Resources. April 4, 2007. http://www.dnr.state.md.us/fisheries/fishfacts/bluecrab.asp. Retrieved February 17, 2011.
- "Blue Crab Frequently Asked Questions'". Blue Crab Archives. December 2008. http://www.bluecrab.info/cooking_faq.htm.
- "Migration". SERC: Smithsonian Environmental Research Center. http://www.serc.si.edu/education/resources/bluecrab/migration.aspx.
- James L. Hench, Richard B. Forward, Sarah D. Carr, Daniel Rittschof & Richard A. Luettich (2004). "Testing a selective tidal-stream transport model: observations of female blue crab (Callinectes sapidus) vertical migration during the spawning season". Limnology and Oceanography 49 (5): 1857–1870. doi:10.4319/lo.2004.49.5.1857.
- "Number of blue brabs in Bay remains below long-term average". National Oceanic and Atmospheric Administration. July 28, 2008. http://www.noaanews.noaa.gov/stories2008/20080728_bluecrab.html.
- 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.
- Vincent Guillory, Harriet Perry & Steve VanderKooy, ed. (October 2001) (PDF). The Blue Crab Fishery of the Gulf of Mexico, United States: a Regional Management Plan. 96. Gulf States Marine Fisheries Commission. http://www.gsmfc.org/publications/GSMFC%20Number%20096.pdf. Retrieved July 22, 2011.
- Benjamin Alexander-Bloch (March 19, 2012). "Louisiana blue crab earns a blue ribbon". The Times-Picayune. http://www.nola.com/dining/index.ssf/2012/03/blue_crab_now_a_certified_sust.html. Retrieved March 19, 2012.