Illinois Natural History Survey - University of Illinois

Yellow Perch Population Assessment in Lake Michigan

John M. Dettmers and Sergiusz Czesny

Yellow perch (Perca flavescens) is an important sport fish for Illinois anglers and is prized for its exceptional quality meat. The nearshore movements of this species make yellow perch available to shoreline as well as boat anglers for the majority of the fishing season. However, yellow perch abundance in Lake Michigan has declined dramatically since 1989, resulting in restrictive harvest regulations to protect this natural resource. Because of the high demand and exploitation of this resource, LMBS conducts 1) annual assessments of the population and 2) directed research designed to determine why young yellow perch survival has been poor during the last decade. LMBS researchers sample yellow perch eggs, larvae, juveniles, and adults during May to October each year. In addition to yellow perch sampling, zooplankton and benthos samples are also collected to examine food resources for larvae and juvenile yellow perch. yp0025pp.jpg
The number of egg skeins produced by spawning yellow perch increased between 1996 and 2002. Despite this increased potential, measurable year classes were produced only in 1998 and 2002. This means that the adult population is maintained almost exclusively by fish hatched in 1998. The causes of poor recruitment are varied and complex. Recently, our research has demonstrated that recruitment of yellow perch increases when the density of zooplankton food available to first feeding larvae is high. At the same time, we are learning that success of yellow perch is also related to the frequency of offshore winds and to zebra mussels. The zebra mussel is a filter feeder that may strongly impact larval yellow perch food resources by competing for the same food needed by zooplankton, the primary food of young yellow perch. Zebra mussel may also interrupt the rate of transfer of essential fatty acids through the food web, affecting the survival of fish larvae (See Essential fatty acids in Lake Michigan food web project description). yp0022pp.jpg


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