Last updated on April 18, 2014 at 1:21 EDT

Blue Crab

Callinectes sapidus, or more familiarly known as the Blue Crab, is a crustacean inhabiting the waters of the western Atlantic Ocean and Gulf of Mexico. Maryland advertises the species as its State Crustacean and consequently, it is the subject of an extensive fishery there. The Blue Crab is particularly aggressive and complicated to handle safely. It is hostile and known to react at any movement they determine a threat.

The western edge of the Atlantic Ocean from Nova Scotia to Argentina is native territory for the Blue Crab. However, it has been introduced in various areas such as Japanese and European waters and has also been found in the Baltic Sea, North Sea, Mediterranean Sea, and Black Sea.

The Blue Crab has many natural predators including eels, drum, spot, trout, some sharks, and cownose sting rays. Blue crabs are considered omnivores, eating small sea creatures and plants, as well as carrion and other Blue Crabs.

The gender of Blue Crabs can be distinguished by their “aprons” or their abdomens. The apron of male crabs is long and narrow, while female crabs have wide, rounded ones. After mating, Chesapeake Bay blue crabs undergo a seasonal migration. The female crabs begin the process by traveling to the southern portion of the Chesapeake where they fertilize their eggs with stored sperm saved up from the previous mating months. In November or December, the female crab discharges her eggs. The tiny larvae hatch and float in the mouth of the bay for 4 to 5 weeks, then the young crabs make their way back up into the bay.

The Chesapeake Bay of Maryland and Virginia is famous for its Blue Crabs. Harvesting of Blue Crabs is a significant contribution to the economies in that region. The overall harvest of Blue Crabs in 1993 was valued at approximately 100 million U.S. dollars. However, declines in harvest have been witnessed in recent years. In 2000, the combined harvest equaled around 45 million dollars. To help grow populations of blue crab, the Maryland Department of Natural Resources instituted tighter guidelines for harvesting in the late twentieth century. Such guidelines include limiting the days and times Blue Crab can be caught as well as implementing a size limit of only 5 to 5¼ inches.

Ironically, while Blue Crab remain a part of popular cuisine in the Chesapeake Bay area, the Bay cannot solely support local demand. The majority of whole blue crabs sold in Maryland restaurants are shipped in from North Carolina, Louisiana, Florida and Texas, while recipes requiring crabmeat are imported from overseas. The annual Blue Crab Festival is hosting in the coastal town of Little River, South Carolina.

Commercially harvested Blue Crabs are captured by using a trap called a “crab pot.” A typical crab pot is made of wire mesh and shaped like a cube with two one-way entrances to allow the crab just enough room to squeeze inside, without exit capability. Some varieties are made of wood and wire, or even all metal versions, but operate by the same principle. A crab pot contains a separate meshed holding cell at the center of the trap that contains bait including bunker, bluefish, chicken or eel. This design entices the crab into the trap but prevents them from being able to remove the bait. Crabbers distribute the traps in long straight lines throughout the harvesting area and checked once a day for catches or depleted bait.

Crabbers sort the crabs into three groups, males called “Jimmies,” immature females called “Sallies,” and mature females called “She-crabs” or “Sooks.” Limit restrictions on females apply, and when sold, they buyer will ask whether he is buying males or females. A final separation occurs upon being sold at market. The crabs with indications of getting ready to molt are termed “busters” and placed in separate shedding tanks. These tanks are usually supported off of the ground and made of concrete blocks, about 3 feet wide and 5 feet tall. The water contained within is circulated bay or river water, and the crabs are then separated into tanks according to molting stage, determined by a pinkish spot on the swimming fins which gradually turns red, before visible indications of the shell separation are visible. The purpose of this continual resorting is to prevent harder shelled crab from eating the ones that have started to shed. After the shed happens and the crab backs out of its shell, it becomes extremely vulnerable because the new shell is like a papery substance which cannot protect the crab. It takes about 48 hours for the new shell to harden completely. Crabbers must attend to the tank constantly to be prepared to grab the crabs right after expanding but before their shells become hardened again. At this point, they are removed and iced or flash frozen for transportation to market as soft shell crabs. If a tank is well tended, there is about a 10% mortality rate. However, a tank that is not well tended mortality rates can be as high as 50%.

Scientists at North Carolina State University and the University of Maryland have developed a new kind of crab harvest based on recent research that could help promote population recovery in blue crab. The idea would be to grow and harvest blue crab in freshwater ponds, rather than from the sea. The researched learned that crabs can tolerate salinity levels of only .3 parts per thousand, which is about the same amount found in tap water of coastal areas. Additional research was conducted to understand the ideal set of circumstances for raising crab including population density, food rations, and habitat structure in ponds.

The most common way to eat blue crabs is still in its hard shell. It is normally prepared on the East coast by steaming in large pots with raised steaming trays, comparable to that used for pasta, and steamed with water, vinegar a seasoning. They are boiled until they turn red, just as lobster and shrimp turn red. It is common to find pre-made season packets called “Crab Boil” or “Shrimp Boil” to add a spicier flavor when cooking Blue Crab.

When crabs are cooked, they are cracked by hand and the meat is pulled out and eaten directly. Crab shells are extremely sharp, so caution is advised to the eater. It can sometimes be difficult to get the meat out of the somewhat pliable, but still hard shell. A tab-like place on the shell of the crab gives you a place to pry the upper and lower shells apart. It is suggested that you removed the gills or “devil” from the bottom of the crab. Also, most people prefer to remove the liver and pancreas of the crab however some consider these parts a delicacy.

Larger pieces of the picked meat, generally obtained from the backfin area, are generally used in recipes like crab cakes, soups, and other dishes. Crab meat is also picked commercially in crab picking “houses” usually operated by local women armed with sharp knives who skillfully pluck out any remnant of meat from claw, backfin, and other various smaller bits.

Soft shell crabs, or crabs caught right after molting and just before they have hardened, are typically prepared by battering in flour, egg, and seasoning and then fried. Most people remove the gills, face and guts before this process. It can be served as an entrée or in a sandwich.

Only about 15% of the meat in a blue crab is edible. The meat is extremely high in vitamin B12, and just 3 ounces of crab meat contain a full day’s suggested portion of the vitamin.

Blue Crabs receive their blue color from numerous pigments in their shell including Alpha-crustacyanin, which mixes with a red pigment, astaxanthin, to create a greenish-blue coloration. A cooked crab turns red-orange because the Alpha-crustacyanin breaks down when boiled, leaving only astaxanthin.

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Blue Crab