A Before-After Control-Impact Assessment of Gravel Washing as a Lacustrine Spawning Habitat Restoration Method for Smallmouth Bass (Micropterus dolomieu)

Smallmouth bass (Micropterus dolomieu) spawn on clean sand and gravel in the littoral zone of lakes, which may become degraded by the presence of fine sediments and decomposing organic matter. Substrate size and composition have been identified as important variables for nest site selection by male bass. I tested whether cleaning substrate with a pressure washer to remove smaller sediment would increase the number of bass nests or the average length of bass nesting in an area the following year using a before-after control-impact design. Treatment was not a significant predictor of nest abundance or average male length. Considering the strength of the experimental design it is reasonable to conclude that this intervention is ineffective in lakes for enhancing spawning substrate for bass. Understanding the factors that maintain productive spawning sites for smallmouth bass is important to restoration effectiveness and determine where habitat enhancement will provide a benefit or not.