An exotic (or invasive) species is any plant or animal that is not native to an ecosystem and that can potentially cause economic or environmental harm, as well as damage to native animal or human health. Several species of exotic fishes in Arkansas have the capability to cause significant economic losses to fisheries and reduce opportunities for effective uses of valued aquatic natural resources. These include seven species within the minnow family Cyprinidae (now considered Leuciscidae), five species in the trout and salmon family Salmonidae, a single species of cichlid (Cichlidae), snakehead (Channidae), smelt (Osmeridae), and yellow perch (Percidae), and two species of pikes (Esocidae).
CYPRINIFORMES: CYPRINIDAE (LEUCISCIDAE)
Rudd or pearl roach (Scardinius erythrophthalmus). This fish apparently entered the United States during two widely separated periods of introduction, either in the late 1800s or early 1900s, where it became established in Maine and New York; a second period of introduction presumably began in the late 1960s or early 1970s. The primary means of rudd gaining access to open waters is thought to be bait bucket release. By 2021, this species had been documented as introduced into twenty states. In the fall of 1987, floods in Arkansas inundated thousands of acres of minnow ponds in the state, and as a result, rudd escaped overland. Fishery biologists in Arkansas had previously stated that it was not established in the state, but recent collections have been made from the lower St. Francis River and Spring River. S. erythropthalmus may find its way into California as a contaminant in golden shiner (Notemigonus crysoleucus) shipments imported as bait from Arkansas. This species has been cultured in Arkansas and Virginia (and possibly elsewhere) as baitfish and distributed to bait stores in several states. Many states, however, have outlawed the use of rudd as live bait, and, as a result, its rapid spread appears to have slowed.
The species is reported to be capable of changing macrophyte communities through selective grazing, which may contribute to regime shifts in the lakes it has invaded. Rudd is a prolific spawner that produces a large number (from 3,500 to 232,000) of small adhesive eggs deposited on submerged vegetation once per year during April to August, when water temperatures rise above about 18° C (64° F). Unfortunately, rudd can breed with native golden shiners to produce hybrid offspring, which could lead to a loss of genetic diversity in the population of golden shiners.
Goldfish (Carassius auratus). This native Eurasian fish species was originally imported into the United States as an aquarium species and is now established in the United States, southern Ontario, southern Alberta, and southern British Columbia, Canada. It was introduced as bait fish in Arkansas. However, the geographic distribution of C. auratus in the state is rather spotty, and no reproducing populations are known to be established in Arkansas, suggesting that, after bait releases, their continual survival is problematic, even though it is environmentally tolerant and is sometimes found in watersheds with high turbidity and some forms of pollution. Goldfish are primarily detritus and vegetation feeders but will also take small benthic invertebrates. In late spring and summer, spawning takes place in shallow weedy areas when water temperatures are above 16° C (60° F). Female C. auratus scatter thousands of adhesive eggs over roots, vegetation, and other stationary objects. Goldfish readily hybridize with the common carp (Cyprinus carpio).
Goldfish are important in the aquaculture industry in Arkansas. For example, I. F. Anderson Farms in Lonoke County spawns and cultivates high-quality bait and forage fish, including C. auratus. In addition, the Frisby Fish Farm and Pool Fisheries, Incorporated, both located in Lonoke County, are producers of quality feeder goldfish.
Asian or common carp (Cyprinus carpio). This carp was first introduced into Arkansas waters in the 1880s and became well established in the state. It is found in a variety of aquatic environs in the state, including lowland rivers and streams as well as upland streams and reservoirs, and can be a nuisance because it increases turbidity of streams by rooting behavior on the bottom substrate. In turn, this can also lower productivity of algae and aquatic macrophytes as well as possibly choking out eggs of other fishes.
Grass carp (Ctenopharyngodon idella). Grass carp are native to rivers of China and Eastern Siberia (Amur River system) that flow into the Pacific Ocean. They were originally stocked in the late 1960s in some lakes (first was Lake Greenlee near Brinkley in Monroe County) in Arkansas for control of aquatic weeds and aquaculture purposes and became well established across the state in impoundments and large rivers. However, grass carp have been reported to not be appropriate for every pond. Because of this potential negative impact of the fast-reproducing grass carp on game fishes, sterile (triploid) grass carp have been developed.
Silver carp (Hypophthalmichthys molitrix). This carp is native to the major Pacific drainages of eastern Asia from the Amur River in far eastern Russia south through much of the eastern half of China to the Pearl River, possibly including northern Vietnam. It was first brought into the United States in 1973 when a private fish farmer imported H. molitrix into the state to stock fish farms in Arkansas. This carp was believed to be ideal for phytoplankton control and as a food source; however, by the 1980s, there were instances of H. molitrix in natural waters of Arkansas (Arkansas and White rivers), and later from accidental escapes in the Mississippi River. Silver carp now occur in the Arkansas, Mississippi, Red, St. Francis, and White rivers (and some of their tributaries) of the state. They are an aggressive fish capable of consuming nearly half of their body weight on a filter-feeding diet consisting primarily of phytoplankton, but they are also known to ingest bacteria, zooplankton, and detritus.
Bighead carp (Hypophthalmichthys nobilis). Bighead carp are native to the large rivers and associated floodplains of southern and central China. Similar to silver carp, H. nobilis is an invasive, fast-growing, large-bodied, highly fecund, voracious fish that is rapidly colonizing the waterways of North America. Bighead carp were first imported in 1973 into the United States by a private fish farmer in Arkansas. The diet of this species overlaps with that of other planktivorous species, such as fish and invertebrates, and to some extent with that of the young of virtually all native fishes. Bighead carp have the ability to deplete plankton stocks for native larval fishes and mussels. Both bighead and silver carp were reported in 2005 from Lake Chicot (Chicot County), and, by 2007, they had grown large enough to cause problems with boating and recreation on the lake. The initial open water record of H. nobilis in Arkansas was two specimens taken from the Arkansas River near Pine Bluff (Jefferson County) in 1986; however, as of the late 1980s, there has been no evidence of natural reproduction in the state.
Black carp (Mylopharyngodon piceus). The native range of M. piceus includes most major Pacific drainages of eastern Asia from the Pearl River basin in China north to the Amur River basin of China and far eastern Russia and possibly to the Honghe or Red rivers of northern Vietnam. It was first imported as a “contaminant” in imported grass carp stocks at a private fish farm in Arkansas in the early 1970s. A major cause for the spread of this carp is flooding of aquaculture facilities and associated numbers and types of escaped fishes. For example, it is very likely that the source of some, if not all, of the M. piceus present in the lower Mississippi River basin occur there from flood events. In addition, as early as 1994, hundreds of young M. piceus were accidentally included in shipments of live baitfish sent from Arkansas to bait dealers in Missouri.
This species can be found in rivers, streams, or lakes, but it requires large rivers to reproduce. Black carp is primarily a bottom-dwelling molluscivore. Juveniles feed on zooplankton and insect larvae, while adults feed on benthic invertebrates such as snails and mussels, so different fauna may become depleted. Therefore, there is great potential that black carp can negatively impact native aquatic communities by feeding on, and reducing, populations of native mussels and snails, many of which are protected species.
In Arkansas, there are five species of non-native trout: the brown trout, rainbow trout, cutthroat trout, brook trout, and lake trout.
Brown trout (Salmo trutta). Originally from Europe and often referred to as the “brownie,” S. trutta is an exotic fish that was first stocked on the North American continent (Michigan and New York) in 1883 and is native to Europe and parts of Asia, from Afghanistan and the Aral Sea across Europe to the British Isles and Iceland, and back across Scandinavia to Cape Kanin, Russia, and farther on to the Barents Sea. In the twenty-first century, S. trutta is found throughout the United States in the Great Lakes area, south in the Appalachians to the northern edge of Georgia, farther south in some high-gradient streams and rivers of the Mississippi River drainage system, throughout much of Nebraska, and in every state west of Texas and Nebraska to the Pacific coast. In Arkansas, S. trutta occurs in streams in the White River below Bull Shoals Dam and in the Little Red River. This trout spawns in the fall or early winter and has been reported to be successful in breeding in some waters in Arkansas, particularly the White River below Bull Shoals.
Rainbow trout (Oncorhynchus mykiss). The rainbow trout is native to the west coast of North America in coastal streams from southern Alaska to Durango, Mexico, and far inland to central Alberta, Canada, and Idaho and Nevada. It has been extensively introduced across the lower Canadian provinces and throughout the area of the Great Lakes to the Atlantic coast, south in the Appalachians to northern Georgia and Alabama, east in the southern United States to western Texas, and sporadically in the central United States as well as above the Great Lakes on the Atlantic coast. In Arkansas, rainbow trout require waters that are constantly below 21° C (70° F), so they are limited to cold water releases from just upstream waters that are discharged from the lower levels of reservoirs, mostly to Ozark and Ouachita spring branches and spring-fed streams. The Arkansas Game and Fish Commission (AGFC) has stocked O. mykiss in the state at various sites, including the White River below Beaver and Bull Shoals dams and North Fork River below Norfork Dam south to Lakes Catherine, Hamilton, and Ouachita; the Ouachita River below Remmel Dam; and the Little Missouri River above and below Lake Greeson. Rainbow trout feed on a variety of invertebrates and vertebrates, but aquatic insects, terrestrial insects, snails, and small fishes often make up the bulk of their diet.
Cutthroat trout (Oncorhynchus clarki). This fish is one of the most widely distributed of all the western trout of North America. The anadromous forms are distributed from the Eel River in California, north to Prince William Sound, Alaska. Non-anadromous (inland) forms occur from southern Alberta, Canada, to as far south as New Mexico, and as far east as Colorado and most of Montana and west to Alberta and eastern California. In Arkansas, it has been stocked into the White River below Bull Shoals Dam and in the North Fork River below Norfork Dam. Cutthroat trout inhabit small, gravel-bottomed mountain streams, rivers, and lakes where they eat mostly aquatic insects, but larger adults will feed on minnows and other fishes. This trout has not been found to reproduce naturally in Arkansas.
Brook trout (Salvelinus fontinalis). The brook trout is a type of char, native to northeastern North America, generally from the Great Lakes north to the Hudson Bay and east to the Atlantic and Arctic coasts. These trout (brookies) occur in the Appalachians southeast of the Great Lakes to the northeastern corner of Georgia, where they inhabit clear, cold mountain streams and lakes and even small creeks and ponds. They have been introduced into areas of upland elevation throughout most of western North America and can be found in scattered locations from the central portions of the lower Canadian Provinces south nearly to Mexico (west of Texas). In Arkansas, only a few S. fontinalis have been stocked in the North Fork River below Norfork Dam; some have been reported to migrate downstream into the White River. It has not been reported to breed successfully in Arkansas.
Lake trout (Salvelinis namaycush). The lake trout is another char that is found throughout most of Canada and into Alaska as well as the Great Lakes, including sections of the western United States, where they have been introduced. Salvelinus namaycush inhabits deeper, cooler waters of lakes, some as deep as 30 to 60 m (100 to 200 ft.). In Arkansas, lake trout were first stocked in 1986 in Bull Shoals and Greers Ferry lakes. Some of the same specimens were later found below Greers Ferry Lake in the Little Red River.
Rainbow smelt (Osmerus mordax). This fish is a Holarctic species that also occurs naturally in northern Asia, northern Europe, and North America. In Arkansas, this smelt has been found only in the Mississippi River, where records include specimens from Chicot, Crittenden, and Mississippi counties. Most sea-run (anadromous) populations of O. mordax occur in cool oceans but travel to cool, clear freshwater streams to spawn. Other populations are landlocked (lacustrine) introductions and are found only in freshwater habitats. In terms of food habits, rainbow smelt feed on small crustaceans, fish, dipteran larvae, mysid shrimp, and insects.
Northern snakehead (Channa argus). A species native to Russia, China, and North and South Korea, ranging from the Amur River to Hainan Island, South China, Channa argus has become established in Arkansas, Delaware, Maryland, Pennsylvania, New Jersey, New York, and Virginia. In 2008, breeding populations of this invasive fish were found in Arkansas in drainage ditches in the Piney Creek system of Lee and Monroe counties as a result of a commercial fish-farming accident. In March 2009, this population was the target of an eradication attempt by AGFC biologists with the application of rotenone to more 700 km (435 mi.) of creeks, ditches, and backwaters. However, more snakeheads were found after this effort. In 2017, an angler reported a snakehead in Old Merrisach Lake near Stuttgart (Arkansas County), and AGFC biologists were able to electrofish (a method used to gather fish through the distribution of a controlled electrical current into the water) and eliminate eight more from that watershed. More recent electrofishing surveys by AGFC personnel in 2018 for northern snakeheads, which have been found downstream of Wilbur D. Mills Dam in Desha County, have not been able to locate any of the invasive species in the river or backwaters upstream of that dam.
Northern pike (Esox lucius). The northern pike is a Holarctic species with a native range in the Arctic, Atlantic, Pacific, Great Lakes, and Mississippi River basins from Labrador, Canada, to Alaska south to Pennsylvania and northern Missouri. It is a predatory fish that will eat a variety of fishes and occasionally even other vertebrate prey. It has considerable commercial value and is an excellent sport fish. Originally stocked as a trophy-size game fish in Arkansas, it once occurred in Beaver, DeGray, Millwood, and Norfork reservoirs. However, a 2000 fishery report on E. lucius in Arkansas suggests that it is extirpated in the state.
Muskellunge (Esox masquinongy). Commonly called the muskie, E. masquinongy has a native range that includes the St. Lawrence River and Great Lakes, Hudson Bay, and Mississippi River basins from Quebec to southeastern Manitoba south to the Appalachians through Georgia and west to Iowa. In Arkansas, E. masquinongy was stocked for trophy fishery into DeGray and Norfork reservoirs but did not successfully establish, and E. lucius seems to be extirpated in the state. The tiger muskellunge is a hybrid (E. lucius × E. masquinongy) produced when a male E. lucius fertilizes the eggs spawned by a female E. masquinongy. This genetic cross was originally released into the state in Lakes Ashbaugh and Frierson in Greene County. In 1989, it was stocked into Spring River Lake, a mainstream impoundment below Mammoth Spring (Fulton County). Like most pikes, it is a predator that feeds primarily on fish but has also been reported to prey on ducks and muskrats.
Blue tilapia (Oreochromis aureus). This invasive fish is native to small warm drainages and impoundments in tropical and subtropical North Africa, the Middle East (Jordan Valley), and Eurasia. The origin of American stocks of O. aureus is via importations from Israel. By 2021, this fish has been reported in at least seventeen U.S. states, including becoming established in Arizona, California, Florida, Louisiana, Nevada, North Carolina, Ohio, and Texas; it also is found in Alabama, Arkansas, Colorado, Georgia, Hawaii, Idaho, Kansas, Oklahoma, and Pennsylvania. In Arkansas, there is a 1998 record of blue tilapia from Pool No. 2 of the lower Arkansas River near Pine Bluff, 3.2 km (2 mi.) below dam No. 3.
The exact reasons for and sources of some introductions are not known but might include: (1) stocking and experimental work by states and private companies, (2) release by individuals seeking to use the species as a sport fish, (3) as forage for warm water predatory fish, (4) as a food source, and (5) as a means of aquatic plant control. Introductions and spread have resulted by way of escapes or releases from aquaculture facilities and experimental control areas, and from various other holding sites like zoos, through aquarium and bait bucket releases, and by intentional transport by anglers and private individuals.
Blue tilapia is considered an excellent food fish; however, the growing season may be too short in central Arkansas to grow them to market size in a single season. They also are commonly sold for bait and raised in farm ponds for food in Arkansas and are becoming increasingly popular as a commercially cultured fish in the state, where they have a variety of aquaculture applications. They can be used to control rooted aquatic vegetation and filamentous algae or to provide forage for channel catfish (Ictalurus punctatus) broodstock, largemouth bass (Micropterus salmoides), or striped bass (Morone saxatilis). Interestingly, electric power companies became interested in using tropical fishes, including blue tilapia, for food or sport in heated effluent ponds used to cool effluents from both nuclear-power-generating and fossil-fuel-fired plants, where temperatures often became too high to support populations of native fishes.
Oreochromis aureus is able to exist and reproduce in freshwater or brackish waters with a minimum temperature of 20° C (68° F). They are mouthbrooders—that is, females deposit 100 to 2,000 eggs in single clutches and, after fertilization, receive the eggs into their mouths and protect them until they hatch about three days later. Young O. aureus remain protected in their mother’s mouth until they are about 1 cm (0.4 in.) long, after which they remain near that parent for about five days before going on their own. Adult O. aureus primarily feed on plankton, detritus, and vegetation such as duckweed, water hyacinth, and algae.
Blue tilapia is considered a competitor with native fishes for spawning areas, food, and space. It has been reported that certain streams where O. aureus is abundant have lost most of the vegetation and nearly all the native fishes. The blue tilapia’s local abundance and high densities in certain areas have resulted in marked changes in fish community structure. Blue tilapia has also been incriminated as the cause for unionid mussel declines in two watersheds in Texas.
Yellow perch (Perca flavescens). This freshwater perciform fish is native to much of northern North America. In the northeastern United States, it is one of the most abundant and well-known panfish. In the east, it ranges from Nova Scotia to the Santee River drainage, South Carolina and west through the Great Lakes states to the edge of British Columbia and into Washington. In 1999, a single individual was collected from the Trimble Creek arm of Bull Shoals Lake (Marion County). The yellow perch was reportedly stocked in Arkansas in 1918; however, until the 1999 report, there had been no subsequent reports of its capture in the state.
For additional information:
Aureli, Thomas J., and Les Torrans. “Spawning Frequency and Fecundity of Blue Tilapia.” Proceedings of the Arkansas Academy of Science 42 (1988): 108. Online at http://scholarworks.uark.edu/jaas/vol42/iss1/32 (accessed September 28, 2021).
Baker, R. F., and W. P. Mathis. “A Survey of Bull Shoals Lake, Arkansas, for the Possibility of an Existing Two-Story Lake Situation.” Proceedings of the 21st Annual Conference of the Association of Game and Fish Commission (1967): 360–368.
Behnke, Robert J. “Salmo clarki (Cutthroat Trout).” In Atlas of North American Freshwater Fishes, edited by David S. Lee, et al. Raleigh: North Carolina State Museum of Natural History, 1980.
———. “Salmo gairdneri (Rainbow Trout).” In Atlas of North American Freshwater Fishes, edited by David S. Lee, et al. Raleigh: North Carolina State Museum of Natural History, 1980.
———. “Salmo trutta (Brown Trout).” In Atlas of North American Freshwater Fishes, edited by David S. Lee, et al. Raleigh: North Carolina State Museum of Natural History, 1980.
Buchanan, Thomas M., Jerry Smith, Diana Saul, Jeff Farwick, Tim Burnley, Mark Oliver, and Ken Shirley. “New Arkansas Records for Two Nonindigenous Fish Species, With a Summary of Previous Introductions of Nonnative Fishes in Arkansas.” Journal of the Arkansas Academy of Science 54 (2000): 143‒145. Online at https://scholarworks.uark.edu/jaas/vol54/iss1/25 (accessed September 28, 2021).
Burkhead, N. M., and J. D. Williams. “An Intergeneric Hybrid of a Native Minnow, the Golden Shiner, and an Exotic Minnow, the Rudd.” Transactions of the American Fisheries Society 120 (1991): 781‒795.
Canonico, G., C. A. Arthington, J. K. McCrary, and M. L. Thieme. “The Effects of Introduced Tilapias on Native Biodiversity.” Aquatic Conservation: Marine and Freshwater Ecosystems 15 (2005): 463‒483.
Carter, F. Allen, and John K. Beadles. “Range Extension of the Silver Carp, Hypophthalmichthys molitrix.” Proceedings of the Arkansas Academy of Science 37 (1983): 80. Online at https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=2534&context=jaas (accessed September 28, 2021).
Douglas, Neil H. The Fishes of Louisiana. Baton Rouge: Claitor’s Publishing Division, 1974.
Etnier, David A., and Wayne C. Starnes. The Fishes of Tennessee. Knoxville: University of Tennessee Press, 1993.
Fuller, P. L., L. G. Nico, and J. D. Williams. Nonindigenous Fishes Introduced Into Inland Waters of the United States. Bethesda, MD: American Fisheries Society, 1999.
Galloway, Marvin L., and Raj V. Kilambi. “Temperature Preference and Tolerance of Grass Carp (Ctenopharyngodon idella).” Proceedings of the Arkansas Academy of Science 38 (1984): 36‒37. Online at https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=2492&context=jaas (accessed September 28, 2021).
Helfman, Gene, Bruce B. Collette, Douglas E. Facey, and Brian W. Bowen. The Diversity of Fishes: Biology, Evolution, and Ecology. New York: John Wiley & Sons, 2009.
Howells, R. G. “Losing the Old Shell Game: Could Mussel Reproductive Failure be Linked to Tilapia?” Info-Mussel Newsletter 3 (1995): 4.
Kilambi, Raj V., and Walter R. Robison. “Age and Growth of Carp from Beaver Reservoir, Arkansas.” Proceedings of the Arkansas Academy of Science 32 (1978): 91‒92. Online at https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=2761&context=jaas (accessed September 28, 2021).
Lee, David S. “Salmo trutta (Brown Trout).” In Atlas of North American Freshwater Fishes, edited by David S. Lee, et al. Raleigh: North Carolina State Museum of Natural History, 1980.
Litvak, M. K., and N. E. Mandrak. “Ecology of Freshwater Baitfish Use in Canada and the United States.” Fisheries 18 (1993): 6‒13.
Martin, B., S. P. Platania, and Don E. McAllister. “Salvelinus namaycush (Lake Trout).” In Atlas of North American Freshwater Fishes, edited by David S. Lee, et al. Raleigh: North Carolina State Museum of Natural History, 1980.
Mettee, Maurice F., Patrick E. O’Neil, and J. Malcolm Pierson. Fishes of Alabama and the Mobile Basin. Birmingham: Oxmoor House, 1996.
Miller, Rudolph J., and Henry W. Robison. Fishes of Oklahoma. Norman: University of Oklahoma Press, 2004.
Morgans, Leland F., and Gary A. Heidt. “Microscopic Anatomy of the Digestive Tract of the White Amur, Ctenopharyngodon idella Val.” Proceedings of the Arkansas Academy of Science 28 (1974): 47‒49. Online at https://scholarworks.uark.edu/cgi/viewcontent.cgi?article=2896&context=jaas (accessed September 28, 2021).
Pflieger, William L. The Fishes of Missouri. Jefferson City: Missouri Department of Conservation, 1997.
Pigg, Jimmy, R. Gibbs, and J. Stahl. “Distribution Records for Three New Introduced Species of the Ichthyofauna of Oklahoma Waters.” Proceedings of the Oklahoma Academy of Science 72 (1992): 1‒2.
Robison, Henry W., and Thomas M. Buchanan. Fishes of Arkansas. Fayetteville: University of Arkansas Press, 1988.
Ross, Stephen T. The Inland Fishes of Mississippi. Jackson: University Press of Mississippi, 2001.
Chris T. McAllister
Eastern Oklahoma State College
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