COMPARISON OF DIEL SAMPLING DATA FOR SAUGER COLLECTED BY ELECTROFISHING

Using a stratified-random sampling design, we sampled sauger (Stizoste dion canadense) by day and night electrofishing during the spring from Lewis and Clark Reservoir, South Dakota-Nebraska. Catch per unit effo rt (number of stock-length (greater than or equal to 20 cm) sauger cau ght 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 c onsistently higher during the day than at night; sauger greater than o r equal to 51 cm were only collected during the day. Differential size structure for samples collected during diel periods should be conside red when biologists design sampling programs or assess population size structure.