The species of heavy-bodied cyprinid fish are collectively known in the United States as Asian carp. Cyprinids from the Indian Subcontinent and mrigal are not included in this classification, and are known collectively as “Indian carp”.
They have been cultivated in aquaculture in China for over 1,000 years. Large-scale silver carp, a more southern species, is native to Vietnam and is cultivated there. Grass, silver, bighead and black carp are known as the “Four Domesticated Fish” in China and are the most important freshwater fish species for food and traditional Chinese medicine. Bighead and silver carp are the most important fish, worldwide, in terms of total aquaculture production. Common carp and crucian carp are also common foodfishes in China and elsewhere. Goldfish, on the other hand, are cultivated mainly as pet fish. Common carp are native to both Eastern Europe and Western Asia, so they are sometimes called a “Eurasian” carp.
There is a long tradition of Asian carp in Chinese culture and literature. A popular lyric circulating as early as 2000 years ago in the late Han period includes an anecdote which relates how a man far away from home sent back to his wife a pair of carp, in which, when the wife opened the fish to cook, she found a silk strip that carried a love note of just two lines: “Eat well to keep fit” (first line) and “Missing you and forget me not” (second line).
At the Yellow River at Henan is a waterfall called the Dragon Gate. It is said that if certain carp called Yulong can climb the cataract they will transform into dragons. Every year in the third month of spring they swim up from the sea and gather in vast numbers in the pool at the foot of the falls. It used to be said that only seventy one could make the climb in any year. When the first succeeded, then the rains would begin to fall. This Dragon Gate was said to have been created after the Flood by the god-emperor Yu who split a mountain blocking the path of the Yellow River. It was so famous that throughout China there was a common saying that: ‘a student facing his examinations is like a carp attempting to leap the Dragon Gate.’
Henan is not the only place where this happens. Many other waterfalls in China also have the name Dragon Gate and much the same is said about them. Other famous Dragon Gates are on the Wei River where it passes through the Lung Sheu Mountains and at Tsin in Shanxi Province. The fish’s jumping feature is set in such a proverbial idiom as “Liyu (Carp) jumps over the Dragon Gate,” an idiom that conveys a vivid image symbolizing a sudden uplifting in one’s social status, as when one ascends into the upper society or has found favor with the royal or a noble family, perhaps through marriage, but in particular through success in the imperial examination. It is therefore an idiom often used to encourage students or children to achieve success through hard work and perseverance. This symbolic image, as well as the image of carp itself, has been one of the most popular themes in Chinese paintings, especially those of popular styles. The fish is usually colored in gold or pink, shimmering with an unmistakably auspicious tone. Yuquan, one of the well-known scenic spots in Hangzhou, has a large fish pond alive with hundreds of carp of various colors. A three-character inscription, Yu-Le-Guo, meaning “fish’s paradise”, is set above one end of the pond in the calligraphy of a famous gentry-scholar of the late Ming Dynasty named Dong Qichang. Many tourists feed the fish with bread crumbs.
Among the various kinds of carp, the silver carp is least expensive in China. The grass carp is still a main delicacy in Hangzhou cuisine. Restaurants along the West Lake of the city keep the fish in cages submerged in the lake water right in front of the restaurant; on an order from a customer, they will dash a live fish on the pavement to kill it before cooking. The fish is normally served with a vinegar-based sweet-and-sour sauce.
Silver carp have become notorious for being easily frightened by boats and personal watercraft, which causes them to leap high into the air. The fish can jump up to 2.5-3 m (8-10 feet) into the air, and numerous boaters have been severely injured by collisions with the fish. According to the EPA, “reported injuries include cuts from fins, black eyes, broken bones, back injuries, and concussions.”. Silver carp can grow to 45 kg (100 lb) in mass. This behavior has sometimes also been attributed to the very similar bighead carp, but this is uncommon. Bighead carp do not normally jump when frightened. Catching jumping carp in nets has become part of the Redneck Fishing Tournament, in Bath, Illinois.
Because of their prominence, and because they were imported to the United States much later than other carp native to Asia, the term “Asian carp” is often used in the United States with the intended meaning of only grass, black, ugly, silver, and bighead carp. In the US, Asian carp are considered to be an invasive species. Of the Asian carp introduced to the United States, only two (crucian and black carp) are not known to be firmly established. Crucian carp is probably extirpated. Since 2003, however, several adult, fertile black carp have been captured from the Atchafalaya and other rivers connected to the Mississippi River. Dr. Leo Nico, in the book Black carp: Biological Synopsis and Risk Assessment of an Introduced Fish, reports that black carp are probably established in the United States. In South Florida, the local water management district actually stocks the canals with sterilized grass carp to control the hydrilla plant, which tends to block the locks and drainage valves used to control water flow from the Everglades.
The common carp was brought to the U.S. in 1831 and has been widespread for a long time. In the late 19th century, it was distributed widely throughout the United States by the United States Fish Commission as a foodfish. However, common carp are not now normally prized as a foodfish in the United States. They are often known to uproot vegetation and muddy water through their habit of rooting in the mud for food. They are thought often to have detrimental effects on native species. However, in Europe common carp are prized as a sportfish, and angling for common carp is enjoying increased popularity in the United States.
In the 1970s, fish farmers in mostly Southern states began importing Asian carp from China to help clean their commercial ponds. The rise in the populations of bighead and silver carp has been dramatic where they are established in the Mississippi River basin. Although many sources cite the record floods of the 1990s as the means by which Asian carp escaped aquaculture ponds into the Mississippi River, this is apocryphal. There is at least one known escape of bighead carp from aquaculture ponds in 1995, but bighead and silver carp were established in the Mississippi River basin prior to 1990. Grass carp have been reproducing in the Mississippi River since the 1970s.
Bighead, silver, and grass carp are known to be well-established in the Mississippi River basin (including tributaries) of the United States, where they at times reach extremely high numbers, especially in the case of the bighead and silver carp. Bighead, silver, and grass carp have been captured in that watershed from Louisiana to South Dakota, Minnesota, and Ohio. Grass carp are also established in at least one other watershed, in Texas, and may be established elsewhere.
The Asian carp have recently been found in Lake Calumet in Illinois. Grass carp have been captured in every Great Lake except Lake Superior, but there is so far no evidence of a reproducing population, although a juvenile grass carp was caught in a river leading to Lake Scugog. No silver carp or black carp have yet been found in any Great Lake. Common carp are abundant throughout the Great Lakes. Current records of where Asian carp have been captured may be found at the United States Geological Survey’s Nonindigenous Aquatic Species website.
These fish are thought to be highly detrimental to the environment in parts of the United States. Because of these concerns, the U.S. Fish and Wildlife Service convened stakeholders to develop a national plan for the management and control of invasive Asian carp (referring to bighead, silver, black and grass carp). The plan was accepted by the National Aquatic Nuisance Species Task Force in the fall of 2007.
In July, 2007, the U.S. Department of the Interior declared all silver carp and largescale silver carp to be injurious species under the Lacey Act. In July 2012, Congress included the “Stop Invasive Species Act” as an amendment to a transportation bill it approved. The Act requires the U.S. Army Corps of Engineers to speed up implementation of strategies to protect the Great Lakes from Asian carp.
Bighead and silver carp feed by filtering plankton from the water. The extremely high abundance of bighead and silver carp has caused great concern because of the potential for competition with native species for food and living space. Because of their filter-feeding habits, they are difficult to capture by normal angling methods.