Simulated Walleye Responses to Various Harvest Regulations in a Nebraska Reservoir

Authors

Mikael Ranta, University of Nebraska, Kearney
Melissa Wuellner, University of Nebraska-KearneyFollow
Keith D. Koupal, Nebraska Game and Parks Commission, Kearney

Date of this Version

Summer 7-28-2025

Document Type

Article

Citation

Ranta, M, Wuellner, MR, and Koupal, KD. (2025). Simulated walleye responses to various regulations in a Nebraska reservoir. Transactions of the Nebraska Academy of Science 45 (2025), pp. 73-83. doi:10.32873/unl.dc.tnas.45.5

Comments

Copyright © 2025 Mikael Ranta, Melissa R. Wuellner, and Keith D. Koupal

Abstract

Recreational fishing provides sociological and economic benefits, and fish populations are managed by state agencies to meet angler expectations. One of the most popular species in Midwest reservoirs are walleye (Sander vitreus), and most of these fisheries have established restrictions on the number and sizes of fish harvested. Regulations are set based on population structure and dynamics and management goals, but often agencies have incomplete information needed to establish regulations. Predictive models can provide insight on population responses and inform managers of the tradeoffs between angler restrictions and population sustainability. Lake McConaughy, Nebraska, supports a popular walleye fishery. Despite annual stockings of age-0 walleye since 1991, annual standard surveys conducted by the Nebraska Game and Parks Commission has shown that the relative abundance of adults has generally declined since the 1990s. Current harvest regulations allow harvest of four walleye, all of which must be at least 38 cm long but only one ≥ 56 cm, but population responses to other possible regulations used in Nebraska and elsewhere to manage walleye are unknown. The objectives of this study were to: 1) model various population outcomes for walleye in Lake McConaughy under different minimum length and bag limits; and 2) compare the proportion of individuals reaching 56 cm under different natural and fishing mortality rates. Models were informed by previous creel interviews and annual standard surveys of walleye by the Nebraska Game and Parks Commission and were constructed in Fisheries Analysis and Modeling Simulator (FAMS). Overall, the population was more sensitive to changes in minimum length limits than bag limits, likely due to rapid growth in body length. Additionally, fishing mortality was a greater limitation to recruitment of fishes to 56 cm than natural mortality. Overall, our approach and results can be informative for state agencies throughout the Midwest in setting the appropriate harvest regulations needed to reach management goals.