Some Factors Associated with Fluctuation in Year-class Strength of Sauger, Lewis and Clark Lake, South Dakota

Abstract

The strength of sauger, Stizostedion canadense (Smith), year classes in Lewis and Clark Lake has fluctuated widely since formation of the reservoir in 1956. Our studies suggest that more than 80% of the variability in year-class strength measured from the catch of fish older than age 0 can be predicted from knowledge of water level change over the spawning ground, June reservoir water temperature, and reservoir water exchange rate. These factors were measured and probably function during the first 2 months of fish life. Sauger year classes of better than average strength can be expected in most years if both power-peaking operations at Fort Randall Dam during the fish spawning and incubation period, and the reservoir water exchange rate during June are minimized.