Effect of Aquatic Macrophyte Removal on Recruitment and Growth of Black Crappies and White Crappies in Lake Conroe, Texas

Abstract

In Lake Conroe, Texas, macrophyte removal by grass carp Ctenopharyngodon idella corresponded to an increase in abundance of threadfin shad Dorosoma petenense. Subsequently, growth rates of black crappies Pomoxis nigromaculatus and white crappies P. annularis increased, and crappie recruitment to harvestable size (254 mm total length) declined by 1–2 years compared with periods when macrophyte coverage ranged from 29 to 44%. First-year growth appeared to be density-dependent for both species. Crappie year-class strength was highly variable, and no consistent trends were evident between age-1 density and macrophyte or threadfin shad abundance. If crappies depend on threadfin shad or other pelagic forage fish for food, and if these prey are negatively affected by excessive macrophyte growth, then plant control should be considered to enhance crappie growth rates.