Age and Growth Companson of Redear Sunfish
and Bluegills in Southern Michigan Lakes

Olen M. Gannon
School of Science and Natural Resources
Lake Superior State University
Sault Ste. Marie, M149783


Abstract Panfish are often the most targeted sportfishes in southern Michigan lakes, with
bluegills (Leponils niacrochinis) being most popular. However, bluegill populations may become
overabundant, resulting in competition for limited resources. Competition for resources leads to
reduced growth rates and small size a "stunted" population. In response to angler demand for
panfish, the Michigan Department of Natural Resources (MDNR) implemented a redear sunfish
(Lepomis microlophus) stocking program in 1984. Redear sunfish exhibit faster growth rates and
have potential to obtain larger sizes than do bluegills. In this study, the objective was to
determine ifthe MDNR's redear sunfish stocking program has provided a quality panfish fishery.
Five lakes with similar morphometry, productivity, and water quality characteristics were used to
determine the stocking program's effectiveness. Fish were collected with trapnets, then length
measurements (mm) and scale samples (to determine age) were obtained from these fish. Age-
frequency analysis demonstrated that the majority of bluegills were age-5, while redear sunfish
were age-3. However, length-frequency analysis (30-mm ranges) showed most bluegills were
within the 170-199mm range, while redear sunfish were within the 200-229mm range . Age and
1ength data did not meet the assumptions of normality (Shapiro-Wilkes, p>0.10), a non-parametric
Mann-Whitney test was used to compare length at age for redear sunfish and bluegills. Between
species, a significant difference (p<0.0001) existed for each age class. These results indicate
redear sunfish grew at faster rates than bluegills and the MDNR's stocking program is providing a
quality panfish fishery.



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