Asian carp are voracious filter feeders that were imported in the 1970s to filter pond water in Arkansas fish farms. They were able to escape because of flooding and establish breeding populations in the Mississippi basin. Their numbers have grown so that Asian carp represent over 97% of the biomass in portions of the Illinois and Mississippi Rivers.
Voracious filter feeders, bighead (Hypophthalmichthys nobilis) and silver, (Hypophthalmichthys molitrix) carp consume up to 20% of their body weight per day in plankton, the small floating plants and animals that are the basis of the food chain. Black carp (Mylopharyngodon piceus) eat mussels and snails, while the vegetarian grass carp (Ctenopharyngodon idella) eat up to 40% of their weight per day of aquatic plants, removing both food and shelter necessary for native fish. These fish are large, with bighead and grass carp growing to 100 pounds or more; silver and black carp grow to 60-70 pounds. The large, hard-headed silver carp can leap up to 10 feet out of the water when startled by boat engines, often colliding with people and causing injuries.
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Efforts to keep Asian carp out of the Great Lakes are ongoing because once they are established in an ecosystem they are almost impossible to remove completely. No natural predators take adult carp and females lay approximately half a million eggs each time they spawn.
Temperatures in the Great Lakes are well within those in the fishes' native range, and nutrient-rich bays, tributaries and other near-shore areas offer Asian carp an abundant food supply. Plankton is eaten by most young and many adult native fishes as well as native mussels and the voracious carp are expected to strip the food web of this resource. There is also a great deal of spawning habitat in the U.S. portion of the Great Lakes suitable for Asian carp.
The Chicago Area Waterways System, a series of sewage and shipping canals, is the most vulnerable path for Asian carp to invade the Great Lakes. The U.S. Army Corps of Engineers maintains electric barriers across the Chicago Sanitary and Ship Canal to stop these invasive fish from entering the Great Lakes. This barrier creates a strong electrical field across the canal to discourage the carp from moving upriver. Asian carp may also be spread through release of bait fish or fish sold live for food, and would do quite well in Pennsylvania rivers.
It is against the law in Pennsylvania to possess, sell or purchase live silver, bighead or black carp or introduce or import these species into Pennsylvania waters. Sterile grass carp can be stocked, but only with a permit.
To avoid spreading invasive species, never release plants, fish, or animals into a body of water unless they came from that body of water.
For more information, visit the Pennsylvania Sea Grant website