Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Animal Ecology

First Advisor

Clay L. Pierce


We explored differences among four well-known indices (%W, %O, %N, and %IRI), plus a modified %IRI (%MIRI), examined diet and consumption dynamics of black crappie (Pomoxis nigromaculatus), largemouth bass (Micropterus salmoides), northern pike (Esox lucius ), smallmouth bass (Micropterus dolomieui), walleye (Stizostedion vitreum), and yellow perch (Perca flavescens ) in Spirit Lake, Iowa, in 1995--1997. %W and %MIRI emphasizes importance of large prey taxa, even when relatively rare in diets, whereas %O and %N emphasize small prey common in diets. %IRI yielded intermediate results. Using %IRI, we found that the most important prey taxa overall were yellow perch, Decapoda, and Amphipoda. Largemouth bass, northern pike, and walleye fed intensively on yellow perch. Smallmouth bass preyed heavily on both yellow perch and decapods. Black crappie and yellow perch largely relied on macroinvertebrates. Yellow perch, logperch (Percina caprodes), walleye, and bluegill (Lepomis macrochirus) were the four most predominant prey fish species over the course of the study. Using bioenergetics models, we found that walleye dominated both the total consumption and consumption of fish in 1995--1997, due to their high abundance and piscivory. We believe that annual intensive walleye stocking in Spirit Lake results in higher consumptive demand on forage fishes and walleye cannibalism compared to other systems in North America. As an important prey as well as dominant predator, yellow perch could influences walleye well-being and compete walleye for food in Spirit Lake, playing a complex role in the trophic dynamics of the fish community. Using data from our study and previous studies, we developed regression models to help fisheries managers to obtain quick approximations of annual population consumption.



Digital Repository @ Iowa State University,

Copyright Owner

Hongsheng Liao



Proquest ID


File Format


File Size

146 pages