Shoreline seining of two typical large Minnesota walleye lakes, Mille Lacs and Winnibigoshish, during the summers of 1954 and 1955 showed young-of-year yellow perch and walleye to be closely associated. Throughout the summer the young walleyes were always larger than the young perch. The average length of walleye ranged from about 1.2 inches in late June to 4.8 inches in late August; that of perch growth for the same period ranged from about 0.9 to 2.5 inches. Food studies demonstrated that throughout the summer young perch fed mostly on plankton crustaceans and aquatic insects and young walleyes fed mostly on fish, especially yellow perch. Yearling and older perch taken from the same seining areas fed principally on plankton crustacea and insects during the first part of the summer and shifted somewhat to fish as the season progressed. Considerable numbers of young walleyes and perch were taken from the seining areas in the summer of 1954. Largest catches of young-of-year walleyes in 1954 were made in July when 1,206 per shoreline acre were taken from Mille Lacs and 795 from Winnibigoshish. In 1955, however, similar seining took markedly fewer fish in Mille Lacs Lake and showed a different seasonal distribution of the catch from Lake Winnibigoshish. Possible reasons for these differences are discussed. The close association of young-of-year walleyes and yellow perch along shores together with their differences of growth rate and feeding habits suggest that in typical walleye lakes the size of the perch crop may be an important factor in determining the year-class strength of the associated walleyes.
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