Density-Dependent Growth of Yellow Perch in

Abstract.—The relationship between the growth rates and abundance of yellow perch Perca flavescens was evaluated in the Indiana waters of Lake Michigan from 1984 to 2004. Relative abundance values were taken from trawl catch per unit effort, while growth rates were determined by back-calculation. Abundance was approximately one order of magnitude higher during the mid-1980s than in 1990–2004. Growth rates were negatively related to relative abundance and were sexually dimorphic (females grew faster than males). Regression analysis indicated that approximately one-half of the observed variation in growth was related to abundance; this was most apparent with smaller and younger fish. Lee’s phenomenon was shown to be present during periods of high exploitation and not present during periods of low exploitation. Both intraspecific competition and physiological changes associated with age at maturity are plausible explanations for these relationships. Growth, recruitment, and mortality are interrelated and can influence the population dynamics of fish populations. For example, growth may play a direct role in recruitment by altering the size of maturation within the fish community (Muth and Wolfert 1986). Growth assessments may also identify management problems, such as population thinning caused by overexploitation (Spangler et al. 1977) and thereby provide feedback on these types of management decisions. In addition, detailed information on growth rates may indicate whether density-dependent biolog-ical factors, such as food availability, cannibalism, and predation, are structuring fish communities (Van Den Avyle and Hayward 1999). Typically, an increase in abundance will increase competition for food resources and a reduction in food resources will then slow growth of fish at specific ages (Henderson 1985). In contrast, low abundance will result in increased growth rates as a result of a decrease in competition for the available food (Le Cren 1958). This particularly applies to yellow perch Perca flavescens because this species has the potential to be highly prolific, leading to rapid fluctuations in population abundance (Schneider 1984) and consequently density-dependent growth (Schneide