Evaluation of Fish Eradication and Game-fish Restocking in a Central Iowa Pond

Changes in fish community and population structure associated with fish eradication and subsequent restocking were investigated in a small (0. 25 ha) impoundment in Boone County, Iowa. In September 1985, when fish were eradicated with rotenone, the fish community consisted of eight species. Large numbers of small bluegills (Lepomis macrochirus), green sunfish (Lepomis ryanellus), and stunted crappies (Pomoxis spp.) dominated the pond numerically, but seven large carp (Cyprinus carpio) and 18 large bigmouth buffalo (lctiobus ryprinellus) constituted 80% of the total biomass. The only quality angling (popular species of desirable size) was for a few largemouth bass (Micropterus salmoides) and channel catfish (Ictalurus punctatus). The pond was then restocked with juvenile bluegills and channel catfish in October 1985, followed by juvenile largemouth bass in June 1986. By autumn 1987, an estimated 110 bluegills (95% confidence limits 72,235) were at least 80 mm long, and 25 large bass (95% confidence limits 16, 61) were in the pond. The quality of sport angling opportunities had been improved, and biomass of centrarchids increased by about half. Total biomass had dropped from 81 kg before eradication in 1985 to 18 kg in 1987, but the loss was primarily carp and buffalo, which are of little interest to Iowa anglers. The pond and its fish community should be monitored periodically to assess quality of habitat and angling opportunities