Asian Carp in Alabama
Former District Fisheries Biologist
Most anglers in Alabama are familiar with grass carp, also referred to as white amur, but few people realize that the grass carp is just one of several species of exotic Asian carps that have been introduced into the United States over the past few decades.
Although a riverine fish in its native range, the grass carp has been introduced into private ponds in Alabama to control aquatic plants and filamentous algae. These fish grow rapidly and specimens over 40 pounds are common. Stocking rates in farm ponds range from 5 to 20 fish per acre depending on the type of plant and the severity of the infestation. Control is usually maintained for several years with proper stocking.
Two other species of Asian carp are also present in Alabama. These are the bighead carp and silver carp. These carp look similar to a grass carp but have very small scales and a keel on their belly. Originally stocked into aquaculture facilities in combinations with catfish to improve water quality and increase fish production, silver carp, bighead carp, and hybrids between the two, have escaped over the years to make their home in the State’s rivers and streams. Based on many reports from anglers and responses to a poster program, biologists for the Division of Wildlife and Freshwater Fisheries identified several wild bighead carp captured by anglers from 1998 through 2008. These fish were much larger than specimens reported from other river basins in the country, with several fish in excess of 100 pounds.
Although anglers sometimes catch them, bighead carp and silver carp are primarily filter feeders, eating a variety of small plants and animals called plankton. The environmental impacts of these fish are unknown but they could adversely impact many native species of fish due to competition for food. Sport fish such as bass and crappie eat plankton early in their lifecycle. Shad also rely heavily on plankton for food. Large numbers of Asian carp could reduce the numbers of shad, which would reduce the amount of forage available for these important sport fish. Although not documented, if Asian carp are reproducing in Alabama, larval and juvenile Asian carp could displace native fishes competing for the already limited backwater nursery habitat so critical to many species. Larger bighead carp are caught on jigs and spoons, so they apparently eat fish.
Large numbers of Asian carp in our rivers could also adversely impact native mussel populations. Alabama has the largest diversity of mussels of any State, but many of these species are already threatened or endangered due primarily to habitat loss. The presence of a large planktivore like these Asian carp could dramatically impact threatened mussels by reducing the amount of food available.
An even greater concern for mussels and other native mollusks would be the introduction of an additional Asian carp in our State’s waters, the black carp. Black carp, which look remarkably like grass carp but with darker fins, primarily eat mollusks such as snails. Catfish production ponds are sometimes subjected to outbreaks of parasites, which kill fish. Snails are an intermediate host for some of the parasites. By stocking black carp, catfish farmers could reduce the numbers of parasites on their fish by reducing the snail population, thus disrupting the parasite’s lifecycle. If these black carp escape from the ponds, just as the bighead and silver carp have, they will begin feeding on a variety of native mollusk species in our river systems with potentially devastating results. Black carp are also known to host at least 32 disease-causing agents, the impacts of which have yet to be fully assessed. Black carp have already escaped into the Mississippi River system from a fish farm in Arkansas.
Thankfully, current Alabama regulations do not allow black carp to be imported, possessed, or released into our State. Another factor working in our favor is that all of these species of Asian carp need very long stretches of moderately flowing water to successfully reproduce. These spawning requirements can be met in some large midwestern rivers but it is hoped that there are no suitable stretches of river in Alabama. Although only large specimens have been collected, if any of these Asian carp are naturally reproducing in Alabama it could cause a significant change in our native fish populations. Due to the natural reproduction that is occurring in the Mississippi and Missouri Rivers, fisheries biologists estimate that bighead and silver carp now make up more than 6 percent of the commercial harvest for certain areas and have displaced many native species.
Asian carp are apparently much more of a threat to the Mississippi and Missouri drainages than they are to the rivers of Alabama at this time. If black carp are introduced or reproduction of bighead or silver carp is discovered however, these fish have the ability to compete and potentially displace native riverine fishes and mollusks.
Due to the relative lack of information concerning Asian carp in Alabama’s rivers, any information that anglers can provide on exotic Asian carp captured would be very important. If you catch a strange looking carp, please contact your local District Fisheries Office immediately.
The US Fish and Wildlife Service has a video explaining the difference between the bighead carp and silver carp.
Date Published: March 8, 2001. Date Updated: December 14, 2012.