Comparison of diel sampling data for sauger collected by electrofishing

Using a stratified-random sampling design, we sampled sauger (Stizostedion canadense) by day and night electrofishing during the spring from Lewis and Clark Reservoir, South Dakota-Nebraska. Catch per unit effort (number of stock-length (greater than or equal to 20 cm) sauger caught per hour of electrofishing) did not vary among three sites (lake, transition area, and river; P=0.64) nor between diel periods (P=0.91). Size structure of samples, indexed using stock density indices, was consistently higher during the day than at night; sauger greater than or equal to 51 cm were only collected during the day. Differential size structure for samples collected during diel periods should be considered when biologists design sampling programs or assess population size structure.