A NEW TECHNIQUE FOR ESTIMATING THE ABUNDANCE AND HABITAT USE OF STREAM FISHES

An open-sampling technique that employed seining and AC electroshockin g with a downstream block net was compared with enclosure sampling in a small river. Relative abundance of species, species diversity and ri chness, total numbers and densities of fish, and median fish size were examined. The two sampling techniques provided concordant fish-assemb lage patterns for riffles and runs. Pool samples showed differences in species diversity and/or dominant species between sampling methods, w hich resulted from fish mobility or sample bias. Fish size did not dif fer significantly between the two methods, and only runs showed notice ably higher fish densities for the enclosure samples.