Intraspecific Resource Partitioning by Yellow Perch (Perca flavescens) in a Stratified Lake

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Abstract
Summer habitat use and relative abundances of different size classes of yellow perch (Perca flavescens) were determined using gill nets set in the main basin, deep bays, and shallow bays of a lake. Niche overlap indices were used to quantify resource use patterns. Size classes spatially segregated into different habitats, but not different depths within a habitat type. Segregation of sexes at different depths was observed with females occupying warm, shallow areas, whereas males were more common in cool, deep water. Formation of an anoxic hypolimnion restricted perch to the epilimnion in late summer, but patterns of habitat segregation observed prior to thermocline formation were maintained. Food partitioning was relatively unimportant in reducing niche overlap. Spatial segregation of perch size classes and sexes may compensate for high diet overlap between conspecifics and reinforces the importance of habitat partitioning in structuring fish communities.