Yellow Perch ( Perca Flavescens) Growth and Mortality Rates in Lake St. Clair and the Three Basins of Lake Erie, 1963–86

Abstract

Growth and mortality rates differed among the three stocks of yellow perch ( Perca flavescens) examined in Lake Erie from 1978 to 1985 in samples obtained from multi-mesh gillnets set in May and July. Growth rates were significantly greater in the central basin than in either the western or eastern basins for yellow perch sampled from four year-classes (1976–79). The lowest growth rates were found among yellow perch from the western basin in the May and July sampling periods. Pooling each age class from 1978 to 1985, we showed that perch from the central basin were usually larger at age. These differences in size at age and growth rates were not explained satisfactorily by differences in population density and water temperature among the basins but could be attributed in part to differences in primary production and fish community structure. Size at age in trawl samples tended to decline in all basins of Lake Erie and Lake St. Clair, particularly in the late 1970s and 1980s, and in the western basin and Lake St. Clair. We suggest that this decline in size may have been caused by both a decrease in primary productivity and the increase in the abundance of white perch (Morone americana). From estimations of total mortality rates derived from cohort catch curves (ages 3–6, 1975–79 year-classes) and annual changes in relative abundance, we concluded that total mortality (Z) was positively correlated with commercial fishing effort (western> central> eastern)