Degree Name

Master of Science (MS)

Semester of Degree Completion


Thesis Director

Leonard Durham


The purpose of this study was to compare the temporal spawning distribution and growth rates of bluegill (Lepomis macrochirus) and redear sunfish (Lepomis microlophus) in Illinois impoundments. Otolith sagittae were used to age the fish and to determine the intervals of successful spawning for both species.

Readear sunfish initiated spawning slightly before or a the same time as bluegill; however, bluegill spawned for twice as long as redear sunfish in all study impoundments. The earliest spawned fish of both species showed the fastest growth and the earliest spawned redear sunfish grew faster than did the earliest spawned bluegill. Growth rates of both species declined constantly, decreasing for each day later in the summer that they were spawned. The length to age regressions were positively correlated showing that the growth rates of the fish declined constantly throughout the growing season. There was a direct relationship between otolith radius and fish length for both species, but the relationship seemed to be population specific and differed among impoundments sampled.