Richard A. Ott, Jr., Texas Parks & Wildlife
Department, Inland Fisheries Division, 11942 FM 848, Tyler, Texas 75707; Voice
903-566-2161;
FAX 903- 566-3542; E-Mail rott@tyler.net
Michael Smart, USAE, Waterways Experiment Station, Lewisville Aquatic
Ecosystem Research Facility, RR 3 Box 446, Lewisville, Texas 75056
Keywords: hydrilla control, plant introduction, fish habitat,
grass carp, herbicide
We developed an integrated management plan was developed to control 48
ha of hydrilla (Hydrilla verticillata) on Lake Jacksonville, Texas (a 547 ha
municipal water-supply reservoir). Our objective was to control a problematic, invasive,
exotic plant while increasing coverage and community diversity of native plants for fish
habitat. Our plan was to reduce hydrilla biomass with aquatic herbicide, stock a minimal
number of grass carp (Ctenopharyngodon idella) to control re-sprouting, and
introduce a diverse native plant community. Hydrilla was treated with Aquathol K in summer
1997 and 1998 followed by stocking 100 grass carp each year. Following each treatment,
native plants representing floating leafed, emergent, and submersed growth forms were
planted in protective cages (to limit herbivory). In fall 1998 hydrilla was found only in
cages where native plant survival was low. Herbivores appeared to be selectively removing
hydrilla from the plant community outside of the cages where it had been observed in
summer 1998. Many of the native plant species introduced in 1997 and 1998 have survived
and are expanding beyond the protective cages. These preliminary results indicate that an
integrated approach has the potential to control hydrilla while promoting diversity of the
native plant community.
