Triploid grass carp (Ctenopharyngodon idella) were stocked at densities of 25 (low), 50 (medium), and 75 (high) fish/vegetated hectare into 9 0.16- to 2.83-ha Texas panhandle ponds to evaluate stocking densities that may reduce, but not eradicate, submersed aquatic macrophytes. Prior to stocking, the ponds had 50%-100% areal coverage of macrophytes. The macrophyte communities included Chara sp., Ceratophyllum demersum, Myriophyllum spicatum, Najas guadalupensis, and Potamogeton spp. The high stocking density eliminated macrophytes in ≤ 13 months. Low stocking densities did not reduce areal coverage of aquatic vegetation 2 or 5 years after stocking. Triploid grass carp stocked at medium densities reduced areal coverage of macrophytes by 27% after 2 years and 42% after 5 years. Our results indicate that triploid grass carp can reduce macrophytes without eradicating them and percentage areal coverage is an effective basis for prescribing stocking rate.
