Carp Impacts on Waterfowl at Malhenr National Wildlife Refuge, Oregon

Carp (Cyprinus carpio) are an exotic fish species which have severe impacts on North American aquatic syst~mS:: disrupting food chains and Qutcompeting native fish and wildlife. Carp were one of the treasures brought to Europe from Asia during trading expeditions to China in the 15th century. They were first imported to the U.S. from Germany in 1877 and were distributed to most states from 1889 to 1897 by the U.S. Bureau of Fisheries. With human help, carp found their way into most U.S. watersheds by the tUfll of the 20th century. Soon after these introductions~ adverse impacts were realized as carp caused reductions of sport fish populations and of waterfowl foods, resulting in lower waterfowl use and production in many wetlands. Attempted elimination of carp is a common practice to improve marshes for waterfowl, since high carp populations are a detriment to waterfowl habitat. They destroy aquatic vegetation (Threinen and Helm 1954, Robel 1961. King and Hunt 1967, Crivelli 1983), and their foraging, spawning and feeding habits increase water turbidity. decreasing macrophyte and invertebrate production, thus decreasing waterfowl food supplies (Berry 1983). The carp's primary foods are aquatic macroinvertebrates. and they directly compete with waterfowl and waterbirds for those resources. Sigler (1958) found a high percentage of invertebrates in the diets of carp and noted that midge larvae (Chironomidae) were their most important food in Utah. Midge larvae are important foods for breeding ducks and ducklings (Swanson 1984) and have also been shown to be important in the diets of mallards (Anas platyrhynchos), northern pintails (A. acuta