Asian carp, a group of invasive species of fish introduced into North America, pose a major threat to the ecology, environment, economy, and way of life in the Upper Midwest and Great Lakes region of the United States and Canada. The term refers to a group of xenocypridid fish species originally native to East Asia, of which several are known to be invasive in the United States, and represent the most urgent potential danger to the ecology of the Great Lakes.
The United States Department of the Interior and United States Fish and Wildlife Service presented their first annual report to Congress on the issue in December 2014. In June 2022, a United States Environmental Protection Agency (EPA) funded initiative to rebrand and rename Asian Carp "Copi" was announced. The new name is a part of the Federal and multi-state campaign to rebrand the destructive carps to the public as a healthy and responsible seafood option in order to decrease its numbers in U.S. waterways.
Background
The four dominant fish species known in the United States as Asian carp are introduced invasive species. They all cause harm within their new environments.
Specifically, the four most well-known species of invasive Asian carp are black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), and bighead carp (Hypophthalmichthys nobilis).
Black carp are carnivorous and feed on native mussels and snails, some of which are already endangered. Grass carp are herbivores that feed on aquatic plants, and can alter the food webs of a new environment by altering the communities of vegetations, invertebrates and fish. Silver and bighead carp are filter feeders of planktons, which are necessary food sources for larval fish and native mussels.
The extremely high abundance of bighead and silver carp in the Mississippi basin has caused great concern because of the potential for competition with native species for food and living space. Because of their algae-eating nature, they are not easily drawn to most baits and are thus difficult to capture by normal angling methods used by recreational fishermen.
Introduction in North America In the 1970s, fish farmers in mostly southern states began importing Asian carp from China to help clean their commercial ponds.The Carp Must Die in BusinessWeek, February 16, 2012.Great Lakes states sue to stop Asian carp invasion in The Capital Times, 13 January 2010. 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.Tucker, J.K, et al. 1996. The Bighead Carp in the Mississippi River. Journal of Freshwater Ecology. 11(2):241-243.Burr, B.M. et al. 1996. Nonnative fishes in Illinois waters: what do the records reveal? Trans. Il. State Academy of Science 89(1-2):73-91. Grass carp have been reproducing in the Mississippi River since the 1970s.Conner et al. 1980. Larval evidence for natural reproduction of the grass carp Ctenopharyngodon idella in the lower Mississippi River. Fourth Annual Larval Fish Conference, Oxford, MO.
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 with the intended meaning of only grass, black, silver, and bighead carp. 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 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.
Jumping ability Silver carp, in particular, have become notorious for being easily frightened by boats and personal watercraft, which causes them to leap high out of the water. The fish, which can grow to in mass, are capable of jumping up to into the air, and numerous boaters have been severely injured by collisions with the airborne fish. According to the EPA, "reported injuries include cuts from fins, black eyes, broken bones, back injuries, and concussions." Bighead carp, however, do not normally jump when frightened.Kolar et al. 2007. Bigheaded carp: Biological synopsis and environmental risk assessment. American Fisheries Society, Bethesda, MD. Catching jumping carp in nets has become part of the Redneck Fishing Tournament, in Bath, Illinois.Crossett, Larry, "Redneck Fishing Tournament draws crowds" , GateHouse News Service/Pekin Times, Aug 09, 2010 8:00 AM. Other parties, such as the Peoria Carp Hunters, have taken advantage of the jumping ability as a mechanism of hunting the carp, in some cases attempting to purge the invasive species. Peculiarly, the extreme jumping behavior appears to be unique to North American silver carp; their relatives in the native Asian ranges are much less prone to jumping even if introduced to other parts of the world. Although theories have been proposed (for example, the high densities the species reaches in parts of North America, or that the introduced North American population may have been descended from a small number of particularly "jumpy" individuals; see founder effect), the reason for these geographic differences is not known for certain.
Presence and threats Proliferation in the Mississippi, Missouri, and Ohio River basins Bighead, silver, and grass carp are known to be well-established in the Mississippi River basin (including its tributaries, the Ohio and Missouri rivers), 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.
In the Great Lakes
The EPA is concerned about the possibility of Asian carp migrating across the Saint Lawrence River divide, to the Great Lakes drainage basin.", Environmental Protection Agency. Retrieved June 1, 2008. In 2002, the U.S. Army Corps of Engineers (USACE) completed an electric fish barrier in the Chicago Sanitary and Ship Canal. The canal connects the Mississippi River drainage basin (via the Illinois River and its tributary the Des Plaines River) to the Great Lakes Waterway (via the Chicago River) and is the only navigable aquatic link between these basins. The initial fish barrier was used as a demonstration project to study the design's effectiveness. Following positive results, construction began on a permanent barrier in 2004."Chicago Fish Barrier ," United States Army Corps of Engineers. Retrieved February 19, 2011. In addition to the canal, USACE has identified 18 sites in 5 additional states, from Minnesota to New York, that could allow for movement of Mississippi basin carp into the Great Lakes.
The Asian carp have been found in Lake Calumet in Illinois. Grass carp have been captured in every Great Lake except Lake Superior, but so far, no evidence indicates a reproducing population. No silver carp or black carp have yet been found in any Great Lake. Common carp are abundant throughout the Great Lakes.
A report issued in 2012 by the Great Lakes Commission concludes that physical separation of the Great Lakes and the Mississippi River watersheds is the best long-term solution to prevent Asian carp and other invasive species from migrating between the waterbodies.
Stopping these invasive carp from spreading into Lake Erie is another concern to many involved, as Lake Erie provides the ideal habitat for the carp to survive. This could lead to the fish choking out the other native fish that exist there, which would result in a major loss for the sport-fishing industry in the area. This is especially true since catching these carp with traditional fishing methods is difficult, which makes it harder for the industry to shift the sport fishing from one fish to another.Egan, D'Arcy, "U.S. Senate takes measures to battle Asian carp invasion: Northeast Ohio Outdoors Notebook", The Plain Dealer, November 29, 2012; updated November 30, 2012. In October 2013, scientists for the first time documented that Asian carp had reproduced in Ohio's Sandusky River, a tributary of Lake Erie. A study released in 2015 detailed the devastating potential of a possible carp invasion on Lake Erie.
In May 2013, a test for silver carp eDNA in the waters of Sturgeon Bay in Lake Michigan near Green Bay, Wisconsin, was positive. May is a month when the carp are active. The result was published in October and scientists re-tested in May 2014.Wines, Michael, "Bracing for Carp in Great Lakes, but Debating Their Presence", New York Times, January 4, 2014. Retrieved 2014-01-06.
In 2016, many Great Lakes charter boat captains have renewed calls for a rapid response to the threat of carp invasion. In August 2016, the Michigan Department of Natural Resources reported that no evidence of Asian carp had been found in their sampling of the state's waters, or that of the Great Lakes system.
Litigation
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.
In response to the Michigan lawsuit, on January 5, 2010, Illinois Attorney General 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.Merrion, Paul, "Illinois fights back as states seek carp-blocking canal closures", Crain's Chicago Business, 4 January 2010. Original access date 2010-01-07; link dead/conversion 2011-09-11.
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. The litigation proceeds in lower courts.