Efficacy of Triploid Grass Carp in Controlling Nuisance Aquatic Vegetation in South Carolina Farm Ponds

Abstract

Abstract This 3-year study addressed the effectiveness of triploid grass carp Ctenopharyngodon idella as a replacement for herbicides to control nuisance aquatic vegetation in South Carolina farm ponds. Vegetation control achieved at three stocking densities as well as losses of grass carp to predation in ponds with largemouth bass Micropterus salmoides were examined. Triploid grass carp stocked at rates not potentially interfering with balanced communities of largemouth bass and bluegills Lepomis macrochirus failed to achieve an arbitrary measure of vegetation control approximately 70% of the time, There was no difference in degree of vegetation control from stocking 12, 25, or 50 fish/hectare, nor was there a decrease in mean plant biomass over a 2-year period. Predation studies with three sizes of largemouth bass demonstrated substantial, although inconsistent, losses of triploid grass carp after 1 month. Mean survival of triploid grass carp ranged from 57% in ponds with 46–51-cm largemouth bass to 72%...