Many species of heavy-bodied cyprinid fish are collectively known in the United States as Asian carp. Cyprinids from the subcontinent [for example, catla (Catla catla) and mrigal (Cirrhinus cirrhosus)] are not included in this classification, and are known collectively as "Indian carp".
Eight Asian carp have been substantially introduced outside of their native ranges:
All the above, except largescale silver carp, have been cultivated in aquaculture in China for over 1,000 years. Large-scale silver carp, a more southern species, is native to, and is cultivated in Vietnam. 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.[1] 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,[2] so they are sometimes called a "Eurasian carp."
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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.[3] According to the EPA, "reported injuries include cuts from fins, black eyes, broken bones, back injuries, and concussions.".[4] Silver carp can grow to 45 kg (100 pounds) in mass.[5] 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.[1] Catching jumping carp in nets has become part of the Redneck Fishing Tournament, in Bath, Illinois.[6]
There is a long tradition of carp in Chinese culture and literature. A popular lyric circulating as early as two thousand 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 (Chinese: 鯉魚; pinyin: Liyu), 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).
The fish's jumping feature is set in such a proverbial idiom as "Liyu (Carp) jumps over the Dragon Gate (Chinese: 鯉躍龍門)," 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 through success in civil examination or through marriage. 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. One of the well-known scenic spots in Hangzhou (Chinese: 花港觀魚)is a big fish pond which has been alive with hundreds of carp of various colors. A three-character inscription, Yu-Le-Guo, meaning "fish’s paradise", set above one end of the pond, is the calligraphy of a famous gentry-scholar of the late Ming Dynasty named Dong Qichang (Chinese: 董其昌). 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 sweet-and-sour sauce (Chinese: 西湖醋魚).
A few bighead carp have been captured from Lake Erie, but there is no evidence they have reproduced there. Another has 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.[7]
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, silver, and bighead carp. In the U.S., 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.[8] However, since 2003, several adult, fertile black carp have been captured from the Atchafalaya and other rivers connected to the Mississippi River.[9] Dr. Leo Nico, in the book Black carp: Biological Synopsis and Risk Assessment of an Introduced Fish, writes that black carp are likely 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.
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 abundances, 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.
These fish are thought to be highly detrimental to the environment in parts of the United States.[10] 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).[11] The plan was accepted by the National Aquatic Nuisance Species Task Force in the fall of 2007.
In July, 2007, all silver carp and largescale silver carp were declared by the U.S. Department of the Interior to be invasive species under the Lacey Act.[4]
The common carp was brought to the U.S. in 1831, and has been widespread for a long time. In the late 19th century, they were distributed widely throughout the United States by the government as a foodfish.[12] However, common carp are now not 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 to often have detrimental effects on native species.[12] However, common carp are prized in Europe as a sportfish, and angling for common carp is enjoying increased popularity in the United States.
The rise in the populations of bighead and silver carp has been dramatic where they are established in the Mississippi River basin.[13] Although many sources cite the record floods of the 1990s as the means by which Asian carp escaped aquaculture ponds into the Mississippi River,[14] 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.[15][16] Grass carp have been reproducing in the Mississippi River since the 1970s.[17]
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.
In Canada, the federal Department of Fisheries and Oceans has evaluated the risk of Asian carp invading Canadian waters, particularly the Great Lakes, either by introduction from the Mississippi or through the market in live carp.[18] A few bighead and grass carp have been captured in Canada's portions of the Great Lakes, but no Asian carp (other than common carp, an originally Eurasian species) is known to be established in Canada at this time. There are concerns the silver carp may spread into Cypress Hills in Alberta and Saskatchewan through Battle Creek (Milk River), the Frenchman River and other rivers flowing south out of the hills into the Milk River. In Mexico, grass carp have been established for many years in at least two river systems, where they are considered invasive, but no other Asian carp are known to have been introduced.
The United States Environmental Protection Agency is also concerned about the possibility of Asian carp migrating to the Great Lakes.[19] In 2002, the U.S. Army Corps of Engineers completed an electric fish barrier in the Chicago Sanitary and Ship Canal, the only navigable aquatic link between the Great Lakes and the Mississippi River drainage basins. The initial fish barrier was used as a demonstration project to study the design's effectiveness. Following positive results, construction began on a second, permanent barrier in 2004.[20] In addition to the canal, the Corp has identified 18 sites in five additional states, from Minnesota to New York, that could allow for movement of Mississippi basin carp into the Great Lakes. [21]
U.S. Representative Dave Camp from Michigan's 4th district and Senator Debbie Stabenow of Michigan introduced the Close All Routes and Prevent Asian Carp Today (CARPACT), which directs the Army Corps of Engineers to take action to prevent Asian carp from entering the Great Lakes, which is estimated to cost more than $30 million in 2010. The act will make sure the locks and sluice gates at the O’Brien Lock and Dam and the Chicago Controlling Works are closed and remain closed until a better strategy is developed. The act will also enhance existing barriers and monitoring systems by giving authority to the Army Corps of Engineers to obtain real estate necessary for the construction and maintenance of the barrier. The Corps also has the authority to eliminate and prevent the spread of the carp by using fish toxicants, commercial fishing and netting, and harvesting.[22]
In November, 2009, carp genetic material was detected beyond the two electric barriers, leaving only a single lock/dam on the Calumet River between the detected presence and Lake Michigan. "This is absolutely an emergency", Joel Brammeier, acting president of the Alliance for the Great Lakes, was quoted as saying, referring to the ecological threat, and also mentioning the threat to recreational boaters. "Mr. Brammeier and some others called for the immediate closing of the lock ... though others doubted it was feasible to stop shipping traffic [there]." "All options are on the table", said Jacqueline Y. Ashmon, a spokeswoman for the Corps of Engineers. "We don’t have any specifics."[23]
In the first week of December, 2009, the Army Corps made plans to shut down one of the electric barriers for maintenance, and the Illinois Department of Natural Resources responded by dumping 2,200 gallons of the toxin rotenone into the canal. Rotenone, the report said, is deadly for fish, but not harmful to humans, animals or most other aquatic life. While "scores" of fish were killed, only one carp was found, near Lockport Lock and Dam and nearly six miles below the electronic barriers.[24] The fish kill cost $3 million and produced 90 tons of dead fish, reported one commentator, who also noted a parallel with an intentional fish kill in Chicago, in Lincoln Park's South Pond, by the IDNR in November, 2008.[25]
Other efforts to reduce the number of Asian carp have included encouraging the public to eat more carp and fisheries shipping the fish to other markets, such as Israel, and have included the participation of then Secretary of State Hillary Clinton.[26]
On June 22, 2010, a 19-pound Asian carp was found near the shore of Lake Michigan, in Lake Calumet, about six miles downstream from Lake Michigan, by a commercial fisherman hired by the state of Illinois to do routine fish sampling in the area.[27] The fish confirms DNA evidence that Asian carp have indeed breached the electric fish barrier on the Chicago Sanitary and Ship Canal.
On August 24, 2010, a carp reportedly knocked a kayaker out of competition in a Missouri River race at Lexington in western Missouri.[28]
On September 8, 2010, the Council on Environmental Quality announced the appointment of John Goss as the Asian Carp Director. Goss' role is primarily to serve as the principal advisor to the CEQ's chair, Nancy Sutley on Asian carp issues, and oversee federal, state, and local coordination on Asian carp control efforts. Goss was previously executive director of the Indiana Wildlife Federation (a state affiliate of the National Wildlife Federation), director of the Indiana Department of Natural Resources, and vice-chairman of the Great Lakes Commission.[29]
On December 21, 2009, Michigan Attorney General Mike Cox filed a lawsuit with the U.S. Supreme Court seeking the immediate closure of the Chicago Sanitary and Ship Canal to keep the Asian carp out of Lake Michigan. Neighboring Great Lakes states and the U.S. Army Corps of Engineers, which constructed the Canal, are co-defendants in the lawsuit.[30]
In response to the Michigan lawsuit, on January 5, 2010, Illinois AG Lisa Madigan filed a counter-suit with the Supreme Court, requesting it to reject Michigan's claims. The Illinois Chamber of Commerce and American Waterways Operators both sided with Illinois in the lawsuit, filing affidavits (amicus briefs) and arguing that closing the Chicago Sanitary and Ship Canal would upset the movement of millions of tons of vital shipments of iron ore, coal, grain and other cargo, totaling more than $1.5 billion a year, and contribute to the loss of hundreds, perhaps thousands of jobs. In response, Michigan noted the value of the sport fishing and recreation industry, already heavily affected in other states with large carp populations, would drop by more than $3.0 billion and result in the loss of at least 4,000 jobs. President Obama and his administration supported Illinois's efforts to keep the canal open; with the support of USGS and U.S. Fish and Wildlife service, reports have consistently denied the Asian carp poses a threat.[31]
On January 19, 2010 the Supreme Court rejected the Michigan injunction request, but took no action on Michigan's separate request to reopen older cases regarding Chicago water withdrawal from Lake Michigan.[32] The litigation proceeds in lower courts.[33]
On January 1, 2010 the Ontario government also filed a lawsuit (alongside the American states) in an American court to stop the dumping of Asian carp into the Great Lakes, a potentially damaging act to the fishing industry (of Canada).[34]
Asian carp have been a popular food fish in Asia for thousands of years. However, many people in North America associate the term carp with common carp, an unrelated bottom-feeding, worse-tasting fish that was introduced from Eurasia much earlier.[35]
The pearly white flesh - complicated by a series of bones - is said to taste like cod or described as tasting like a cross between scallops and crabmeat. They are low in mercury because they do not eat other fish. To make the fish more appealing to American consumers, the fish have been renamed silverfin or Kentucky tuna. [36] Volunteer efforts to increase the popularity further include making and selling carp-based dishes and using the entrails to make fertilizer.[37] Carp caviar is also increasing in popularity and is an alternative to further endangering sturgeon.