Evaluating Pond Shoreline Treatments of Slurried Hydrated Lime for Reducing Marsh Rams-Horn Snail Populations

Abstract

Trematode parasites can cause massive infections in commercially raised fish. The most promising approach for the control of these infections is the reduction or elimination of snails that serve as vectors for the trematodes. A recent approach, the application of high concentrations of slurried hydrated lime (SHL) or copper sulfate pentahydrate (CSP) along pond margins (shoreline treatment), has shown promise in reducing populations of the marsh rams-horn snail Planorbella trivolvis (the snail vector of Bolbophorus damnificus and Clinostomum marginatum) in experimental ponds. While CSP has been shown to effectively reduce snail numbers, treatment efficacy and application methods using SHL have not been well defined. Four SHL treatments were evaluated for their ability to kill marsh rams-horn snails in experimental units designed to mimic commercial aquaculture ponds. The treatments were applied at water temperatures of 75–79°F (24–26°C), total alkalinity of 137–257 mg CaCO₃/L of water, and total hardness of 86–120 mg CaCO₃/L. All tested SHL applications reduced snail numbers; however, the applications of 100 lb of hydrated lime per 100 linear feet (3-ft swath) and 175 lb per 100 ft (6-ft swath) were the most effective, resulting in 97.2% and 98.3% reductions in snail survival, respectively.