Development of Dominant Year Classes in a Yellow Perch Population

Abstract
Abundance of young-of-the-year yellow perch in Oneida Lake, New York was estimated in 1959 through 1968 by shore seining in July and trawling in late summer. Seine and trawl catches were high in 1960, 1962, 1964, and 1968 and catches of age I+ perch in subsequent years confirmed that these were dominant year classes. Variation in numerical size of year classes was less in the first year than in the second which indicated a divergence in year class abundance. Estimates of mortality based on the catch in trawls from August to October confirmed that weak year classes generally experienced higher mortality than strong year classes, thus mortality was depensatory. Changes in year class bio-mass and estimates of perch consumed by the walleye population were consistent with the assumption that depensatory mortality was caused by predation.

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