Blue crab

Taxobox | name = Blue crab

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image_width = 250px
regnum = Animalia
phylum = Arthropoda
subphylum = Crustacea
classis = Malacostraca
ordo = Decapoda
subordo = Pleocyemata
infraordo = Brachyura
familia = Portunidae
genus = "Callinectes"
species = "C. sapidus"
binomial = "Callinectes sapidus"
binomial_authority = Rathbun, 1896

The blue crab ("Callinectes sapidus", from the Greek "calli"="beautiful", "nectes"="swimmer", and Latin "sapidus"="savory") is a crustacean found in the waters of the western Atlantic Ocean and Gulf of Mexico, which is the Maryland State Crustacean and the subject of an extensive fishery.cite web |url=http://www.mdarchives.state.md.us/msa/mdmanual/01glance/html/symbols/crab.html |title=Maryland State Crustacean |date=2005-12-27 |publisher=Maryland State Archives] They can deliver an extremely painful pinch and are noted for being particularly aggressive (even out of the water, they will lunge towards movement they consider a threat) and difficult to handle safely.

Distribution and ecology

The blue crab is native to the western edge of the Atlantic Ocean from Nova Scotia to Argentina. [cite web |url=http://www.sms.si.edu/IRLSpec/Callin_sapidu.htm |title="Callinectes sapidus" |publisher=Smithsonian Marine Station at Fort Pierce |date=2004-10-11] It has been introduced (via ballast water) to Japanese and European waters and has been observed from the Baltic Sea, North Sea, Mediterranean Sea and Black Sea. [cite web |title="Callinectes sapidus" |publisher=CIESM: The Mediterranean Marine Research Network |month=August | year=2006 |url=http://www.ciesm.org/atlas/Callinectessapidus.html]

The natural predators of the blue crab include eels, drum, spot, trout, some sharks, and cownose sting rays. The blue crab is an omnivore, eating both plants and animals. Blue crabs typically consume thin-shelled bivalves, annelids, fish, plants and nearly any other item they can find, including carrion.

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 100 million U.S. dollars. Over the years the harvests of the blue crab dropped [ [http://www.noaanews.noaa.gov/stories2008/20080728_bluecrab.html "Report: Number of Blue Crabs in Bay Remains Below Long-Term Average"] , National Oceanic and Atmospheric Administration, July 28, 2008] ; in 2000, the combined harvest was around 45 million dollars. Late in the twentieth century, the Maryland Department of Natural Resources created stricter guidelines for harvesting blue crabs to help increase populationsFact|date=February 2007. These include raising the legal size from 5 to 5¼ inches (from 12.7 to 13.3 cm) and limiting the days and times they may be caught.

While blue crabs remain a popular food in the Chesapeake Bay area, the Bay is not capable of meeting local demand. Most whole blue crabs sold in restaurants in Maryland are shipped into the region from North Carolina, Louisiana, Florida and Texas and many crabcakes are made of crabmeat imported from overseas. At least one well-known "traditional Maryland" seafood restaurant [ [http://www.baltimoresun.com/business/bal-te.bz.phillips07jan07,0,3010222.story Baltimore Sun, 2007] ] actually imports a Southeast Asian crab, an industry there that employs about 15,000 people.

Harvesting techniques

Blue crabs are commercially harvested by using a trap known as a "crab pot" (similar to a Lobster pot). The crab pot is made out of wire mesh (older designs of wood and wire also exist, as well as all metal varieties) and is cubical in shape. The crab pot usually contains two "entrances" for the crabs that prohibit exit. These are in the form of a tapered aperture that allows the crab to squeeze through in one direction only. A crab pot is baited with any of several types of meat, including bunker, bluefish, chicken or eel. The bait is placed in a holding compartment, a separate meshed enclosure in the center of the pot which is accessible through a door on the bottom of the crab pot. This design attracts the crabs through the entrances while preventing them from completely removing the bait. The pots are distributed throughout the crabber's harvesting area in long straight lines and are checked approximately once a day for captures or depleted bait. Crabs that are caught are removed, and the pot is re-baited for the next day.

Crabbers sort the crabs into males ("jimmies") and females ("sooks" or "she-crabs"), and further sort the females into those gravid (with eggs) or not. Catch limits for females are more restrictive than for males, and when sold, the buyer will want to know whether he is buying males or females. Those crabs with signs of getting ready to molt or shed are called "busters" and are also separated from the rest, and placed in shedding tanks. These tanks are usually raised and made of concrete blocks, about 3 feet by 5 feet in size. The water is constantly circulated bay or river water, and the crabs are separated into tanks according to the molting stage, determined by a pinkish spot on the swimming fins which gradually turns red, before visible signs of the shell separation are visible. This continual resorting helps prevent the harder shelled crabs from eating the ones that are beginning to actually shed. Once the shed happens, the pressure of the needing-to-be-larger crab helps the shell to crack, and the crab then backs out of the shell. At this point it is extremely vulnerable because the new shell is a gelatinous papery substance which does not protect the crab. Right after shedding, you can observe the crab becoming noticibly larger because the new shell also expands until it hardens, which takes about 48 hours. Crabbers are constantly tending the tank, and after the expansion, the crabs are removed and iced or flash frozen for transportation to market as soft shell crabs. In well tended shedding tanks there is about a 10% mortality rate. If the shedding process is not managed, the mortality can be as high as 50%.

For the recreational crabber, there exist a variety of crab traps. (Recreational crabbers rarely use commercial pots.) The design of a trap can vary widely, but the common varieties are made out of wire mesh. The crab trap is usually cubical or pyramidal in shape although cylindrical designs are also used. The crab trap contains some form of "entrance" for the crabs, such as hinged panels, that are typically closed as the trap is raised from the water. Like the commercial pots, the crab trap is baited with any of several types of meat, chicken usually being the easiest to obtain. The bait is placed in a holding spot in the middle of the trap usually in some form of clip allowing the crab direct access. This design has the potential to more easily allow the crab to escape with the bait but the trap is usually checked frequently enough (every 15 to 30 minutes) to prevent this from happening.Some recreational crabbers add the catch from the traps to a "keeper pot" that holds the live crabs until a substantial harvest is accumulated. When the keeper pot is appreciably full, the contents are prepared for a "crab feast" or for sale.

Crabs can also be caught with a trotline. While this method generally allows one to catch more crabs than other recreational methods, it requires more effort and equipment. This method is used by advanced recreational crabbers and some smaller commercial operations. Other recreational methods involve line crabbing (using a single baited line similar to fishing) or simply wading through the water with a dip net. Crabs can also be taken from a slow-moving motorboat. During the day, crabbers will operate the boat in shallow, grassy waters (flats) and use a long-handled net to scoop them from the bottom, where they can be easily seen moving about. At night, the crabs swim in deeper water. By scanning the water ahead of the boat using a spotlight, the crabs are easily seen and caught.

Preparation

Blue crabs are most often eaten in the hard shell. Steaming them in large pots with water, vinegar and seasoning (Old Bay Seasoning is a popular variety in Maryland) is the norm on the East coast. The crabs are placed on a raised tray (with holes for the steam), in large cooking pots similar to pot used for cooking pasta. There is water under the tray. As the crabs are layered into the pot large amounts of the seasoning (usually Old Bay) are sprinkled between the layers. The lid is then placed on the pot and kept at boiling until the crabs turn red - just as lobsters and shrimp also turn red.

However, places like New Orleans tend to boil them in water and heavy cajun seasoning which is similar to boiling crawfish. Stores carry this as "Crab Boil" or "Shrimp Boil" spice, which is added to the water, and the crabs are immersed in the water. Again, they are done when they turn red.

The cooked crabs are cracked by hand, and the meat pulled out and eaten directly. Crab shells are wickedly sharp, so the eater of crabs is going to work for the eating pleasure. Because the interior of the crab is also a series of compartments separated by a somewhat pliable but still sharp shell, getting the meat out is also a lot of work for small amount of edible crab. Crabs are often referred as having a tab, like beer cans have for opening. The male tab is sometimes referred to as the Washington Monument because of the long straight tab, while the tabs on females are referred to as the Jefferson Monument in shape. This tab is pried up and pulled off, which gives you a place to pry the upper and lower shells apart. On the bottom of the crab, you then remove the gills or "devil". There is also the crab's equivalent of a liver and pancreas, which is considered a high delicacy by native crab eaters, but usually removed by those who came to crabs later in life. This is called 'tomalley' or, in Maryland and Virginia, referred to as 'mustar' or 'mustard', probably referring to the color, similar to Dijon mustard.

The picked meat, especially the large chunks from the backfin area, can also be used to make crab cakes, crab soup, or other dishes. Picked crab meat is also sold commercially, and the canning operations have huge crab picking 'houses' usually manned by local women armed with sharp knives and who manage to completely remove the meat, sorted into lump, claw, backfin, and the other smaller bits, in less time than a the usual crab eater takes just to get into one crab, remove the gills, and pry out the lumps. Local Maryland and Virginia crab eaters know not to eat crab cakes - even if labeled "Maryland" anywhere other than in Maryland and Virginia. Larger pieces of meat are preferred by customers, but since they fall apart easily, a cook has to carefully fold in crab meat, rather than stir it. A true crab cake has only a small amount of breading, if any, just enough egg to hold it together, and very little in spice, although over the years, more and more Old Bay spice is being added, which wasn't usually used in crab cakes prior to around 1980s. Traditionally crab cakes were fried, but many people today prefer broiled.

Crabs caught just after molting (before the new shell has had time to harden) are prepared as soft shell crabs. Soft shell crabs are prepared by first cutting out the gills, face, and guts. The crab is then battered in flour, egg, and seasoning, then fried in oil until crispy. The result can be served as an entrée, or in a sandwich. When served between bread slices or crackers, the legs stick out on either side, and the entire crab is consumed, legs and all.

Blue crabs average 15% edible meat, and that meat is high in vitamin B₁₂. Just three ounces of crab meat contain a full day's allowance of the vitamin.

References

External links

* [http://www.bluecrab.info/lifecycle.html Blue Crab Life Cycle]
* [http://www.skipjack.net/le_shore/crab/ The Maryland Blue Crab] Blue crab fact and information website.
* [http://www.newscientist.com/channel/life/dn13603-boy-crabs-boogie-to-bring-females-out-of-hiding.html?feedId=online-news_rss20 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
* [http://ap.google.com/article/ALeqM5gKPhZPk1dBPUwT7Lp_DWBU3hk_CQD91UTB3G2 Chesapeake watermen fear blue crab not coming back] - Associated Press, July 16, 2008