Effects of simazine treatment on channel catfish and bluegill production in ponds

Application of 13.4 kg/ha of simazine to the bottom of channel catfish (Ictalurus punctatus) ponds before flooding resulted in an extended period of low dissolved oxygen, a 19% reduction (P < 0.01) in channel catfish yield, and poorer feed conversion by fish when compared to control ponds. A single application of 1.5 mg/l of simazine to the water of fertilized bluegill (Lepomis macrochirus) ponds also decreased dissolved oxygen. The 11% reduction in bluegill yield was not statistically significant (P > 0.05). Simazine treatment caused an initial reduction in macrophyte coverage in bluegill ponds, but macrophyte coverage increased as simazine concentrations in the pond water declined.