Underwater Methods for Sampling the Distribution and Abundance of Smallmouth Bass in Lake Washington and Lake Union

Direct underwater observations were used to characterize habitat use and to quantify abundance of smallmouth bass in the littoral zones of Lake Washington and Lake Union during the spring and summer of 2000 and 2001. We evaluated monthly changes in density, size structure, size-specific selection of natural vs. artificial structure, and nest-site characteristics of smallmouth bass at several locations. Integrating diver observations, side-scan sonar imagery, global positioning system (GPS) data, and geographic information systems (GIS) should provide maps of smallmouth bass distribution and abundance that will benefit resource managers and anglers alike.