Impact of Alewife Introduction on Walleye and White Bass Condition in Lake McConaughy, Nebraska, 1980-1995

Abstract

We examined relative weight (W _r) relationships of walleye Stizostedion vitreum and white bass Morone chrysops before and after the addition of alewife Alosa pseudoharengus in Lake McConaughy, Nebraska, where gizzard shad Dorosoma cepedianum had been the primary prey. Walleyes and white bass were collected in fall gillnetting surveys from 1980 to 1995. A general linear model was constructed to determine the least-squares means of walleye and white bass W _rs by length category and year. Contrast statements were used to test for significant differences in the annual W _rs of walleye and white bass population length categories before and after the establishment of alewives. The annual mean W _rs of walleyes of stock to quality (S-Q), quality to preferred (Q-P), and preferred to memorable (P-M) lengths and Q-P-length white bass increased significantly, whereas that of S-Q-length and P-M-length white bass decreased significantly after 1988. The introduction of alewives changed the body condition of walleyes and white bass in Lake McConaughy, Nebraska.