CHANGES IN PREY FISH POPULATIONS IN WESTERN LAKE ERIE, 1969-88, AS RELATED TO WALLEYE, STIZOSTEDION-VITREUM, PREDATION

Relative abundance of the total prey fish community in the western bas in of Lake Erie varied little from 1969 to 1988, but species compositi on changed significantly. Soft-rayed fishes such as emerald shiner, No tropis atherinoides, spottail shiner, N. hudsonius, and alewife, Alosa pseudoharengus, declined significantly after 1977 whereas only one sp iny-rayed species, white bass, Morone chrysops, declined over the same period. Trout-perch, Percopsis omiscomaycus, a relatively abundant sp ecies rarely eaten by piscivores in this system, experienced only mino r shifts in abundance between 1969 and 1988. Although several factors could be responsible for the shift in species composition, predation b y increasingly abundant walleye, Stizostedion vitreum, played a major role. Walleye prefer to eat soft-rayed fishes; thus, observed shifts i n the community match expectations of selection noted in the diet. We suggest that management goals focusing primarily on walleye affected n ot only the targeted species but the entire fish community of western Lake Erie.