Biology, Management, and Culture of Walleye and Sauger

Chapter 9: Population and Community Dynamics of Walleye

Nancy A. Nate, Michael J. Hansen, Lars G. Rudstam, Roger L. Knight, and Steven P. Newman


The term “fish population dynamics” may be used to describe changes in fish population attributes for individual populations or among multiple stocks of fish over time, or may describe changes over time in fish population metrics from many individual populations (e.g., meta-populations) over a large spatial area. The dynamics of fish populations may be described as changes in any measurable fish population metric or dynamic rate such as abundance, biomass, size structure, age at maturity, body condition, growth, recruitment, or mortality. Summaries of species metrics from many systems across a geographic range provide useful benchmarks for comparison when managing a particular species (e.g., relative weight comparisons, Wege and Anderson 1978), and were presented in earlier chapters. Nested within such comparisons of metrics across many systems is variation associated with differences in sampling methodologies among lakes, years, and systems, and inherent ecological differences among lakes. An approach that minimizes these sources of variation, such as a case study approach, enables an exploration of the magnitude of change possible for any one metric over time.

Herein, we present case histories from three aquatic ecosystems to examine the magnitude of change possible in walleye population metrics and dynamic rates. Each case history presents a long time series of data collected in a relatively consistent manner, and includes multiple fish population metrics presenting a unique opportunity for comparison and synthesis. Because our chapter focus was on temporal changes in population metrics, the case studies were selected based on the availability of long-term data and where walleyes are the predominant predator. Case studies are presented from a small lake (119 ha), Escanaba Lake, Wisconsin; a medium-sized lake (20,670 ha), Oneida Lake, New York, and a large lake (2,565,700 ha), Lake Erie. We acknowledge that walleyes occur in lakes and rivers, and therefore the conclusions may differ for river populations. The lakes selected are similar in geographic location (latitude 42–46°N) but differ in morphology and management.