Grass carp Ctenopharyngodon idella or white amur were imported from eastern Asia in 1963 to control submersed aquatic vegetation in aquaculture ponds. Escapement from these aquaculture facilities occurred soon after importation and grass carp in the wild were first documented in the Mississippi River along Illinois in 1971. Since that time grass carp have rapidly spread to 45 states through the accidental and intentional, legal and illegal release by numerous state and federal agencies, private groups and individuals. Grass carp began to appear in the catches of Arkansas’ commercial fisheries in the early 1970's, and by 1976, 25 tons were reported taken statewide. Stocking of grass carp for control of aquatic vegetation was legalized in Oklahoma in the early 1980's. Currently grass carp are available for purchase for private use through a number of commercial fish producers in the state. The Oklahoma Department of Wildlife Conservation (ODWC) currently uses grass carp on its four fish hatcheries for control of aquatic vegetation in culture ponds. Grass carp orient to flow and will quickly leave ponds when water is flowing over the spillway. Today grass carp can be found in most reservoirs in Oklahoma and reproduction of grass carp has been verified in Lake Texoma by ODWC biologists. Negative impacts on native organisms have been summarized to include: competition for food with invertebrates (i.e., crayfish) and other fishes; significant changes in the composition of aquatic vegetation, phytoplankton, and invertebrate communities; interference with the reproduction of other fishes; modification or elimination of preferred fish habitats; enrichment and eutrophication of lakes; disruption of food webs and trophic structure; and introduction of nonnative parasites and diseases.
Regulations Pertaining to Grass Carp
800:20-1-2. List of restricted exotic species
Grass carp: Release of grass carp (diploid and/or triploid), also known as white amur or Chinese carp (Ctenopharyngodon idella) or their hybrids into public waters is prohibited in accordance with 29 O.S., Section 6-504. Only certified triploid grass carp may be imported, possessed, or introduced for the purpose of stocking private waters. Possession and transportation of diploid grass carp is permitted for the control of vegetation on licensed aquaculture facilities, the export to states allowing use of diploid grass carp and for production for sale to the human food market.
The importation and possession of the next two species of Asian carp are illegal in Oklahoma without the written consent of the ODWC Director. Approval has been given for research purposes only.
Bighead carp Hypophthalmichthys nobilis, native to the large rivers of eastern China, were first brought to the U.S. in 1972 by a private fish farmer in Arkansas to improve water quality and increase fish production in culture ponds. Bighead carp first began to appear in open public waters in the early 1980's. The species has now been recorded from within, or along the borders of, at least 18 states and are actively reproducing up and down the Mississippi River. Bighead carp have been reported from the Neosho River above Grand Lake and the Grand River below Grand Lake. The presence of bighead carp in Lake Hudson has been verified by ODWC biologists. Bighead carp have also been found in the Kiamichi River below Hugo Reservoir which makes it a certainty that they exist in the Red River.
Bighead carp have been reported to be “piling up” in large numbers below dams on many Midwestern rivers, and filling the nets of commercial fishermen to the point that nets can not be lifted and sites have to be abandoned. The bighead carp is a very large deep-bodied, somewhat laterally compressed (narrow) fish with a very large head. Scales are very tiny, resembling those of trout, and the eyes are situated below the midline of the body. Gill rakers are long, comblike and close-set allowing the species to strain plankton from the water for food. The bighead carp utilizes open water areas, moving about in the surface zones of large lowland rivers, consuming large quantities of bluegreen algae, zooplankton, and aquatic insect larvae and adults. Because of its feeding habits, bighead carp is a direct competitor with paddlefish, bigmouth buffalo, and gizzard shad; as well as with all larval and juvenile fishes and native mussels. Bighead carp have the unusual habit of jumping out of the water from the sound of outboard motors. The problem has become so severe on the Missouri River that water skiers have quit using the river.
The silver carp Hypophthalmichthys molitrix is also native to the large rivers of eastern China and looks and acts very similar to the bighead carp. Bighead carp have a keel on the belly that extends only partway to the head and has dark blotches along the back. The keel on silver carp extends all the way to the head. Silver carp have a smaller head and mouth than the bighead carp. Like bighead carp, silver carp were imported into Arkansas in 1973 for use as phytoplankton control in culture ponds and as a potential food fish. Silver carp are efficient at straining suspended material from the water through use of gill rakers that are fused into sponge-like porous plates. Silver carp are also a competitor with all larval and juvenile fishes as well as adult paddlefish, bigmouth buffalo, and gizzard shad. Silver carp have spread throughout the large rivers in the Mississippi basin and are reproducing in off-channel and backwater habitats. Silver carp have been found in both the Arkansas and Red rivers in Oklahoma. Small silver carp and bighead carp resemble gizzard shad. Cast-netting for bait in tailwaters below some major reservoirs in Oklahoma has the potential to introduce Asian carp into some of the premier sportfishing lakes in the state. Anglers routinely cast net for bait below the Texoma Dam and use the bait to fish for striped bass or catfish in Lake Texoma. Asian carp can be accidentally introduced into the lake through this practice. Bighead and silver carp have reproductive requirements similar to those of striped bass. There is a real potential to establish a reproducing population of Asian carp in Lake Texoma which could be devastating to striped bass fishery and paddlefish recovery efforts.
What can you do to help stop the spread of Asian carp?
- Consult local conservation authorities about laws and regulations governing importation, culture and stocking.
- Ask your bait dealer where their baitfish came from and never release any unused baitfish to the wild.
- Never release pet fish or aquatic organisms from the home aquarium to public water