Skip to main content
U.S. flag

An official website of the United States government

Effects of exploitation and emigration on apparent survival of Walleye in Lake Sharpe, South Dakota

December 12, 2024

Objective

In 2017, we began a 5-year mark–recapture study to estimate apparent survival of Walleye Sander vitreus and angler exploitation in Lake Sharpe, South Dakota, and inform management strategies for this fishery. The study revealed substantial downstream emigration of Walleye; therefore, we also examined the influence of emigration on apparent mortality.

Methods

We estimated Walleye apparent survival using the Seber parameterization of the dead recovery model. In our models, we included factors influencing voluntary fish release, as well as harvest restrictions, tagging location, and year. We used a multistate Markov model to estimate emigration in relation to Walleye total length, sex, and tagging location, as well as annual reservoir discharge. The exploitation and emigration estimates informed our interpretations of annual Walleye apparent survival.

Result

Apparent survival patterns were explained by an interaction between Walleye length and a minimum harvest length restriction. Apparent survival was lower during July and August, when the minimum harvest length limit was suspended, and results suggest that anglers were willing to release preferred sizes (≥508 mm) when able to harvest smaller (<381 mm) Walleye. Annual apparent survival, exploitation, and emigration estimates ranged between 15% and 47%, 8% and 25%, and 11% and 28%, respectively. Emigration was influenced by tagging location and annual discharge: increasing with proximity to Big Bend dam and during high annual flows. Although years with high exploitation or emigration corresponded to years with low apparent survival, estimates did not explain the magnitude of mortality or emigration indicated by survival models.

Conclusion

Our results revealed that harvest–release decisions by Walleye anglers in Lake Sharpe are primarily influenced by regulations, although exploitation was not a significant source of mortality. Annual patterns in apparent survival indicate high mortality or emigration. Continued investigations into immigration and emigration and sources of mortality of Lake Sharpe Walleye are warranted to better inform management strategies for the fishery.

Publication Year 2024
Title Effects of exploitation and emigration on apparent survival of Walleye in Lake Sharpe, South Dakota
DOI 10.1002/nafm.11062
Authors Laurel H. Sacco, Mark J. Fincel, Cameron W. Goble, Tanner Davis, Steven R. Chipps
Publication Type Article
Publication Subtype Journal Article
Series Title North American Journal of Fisheries Management
Index ID 70262208
Record Source USGS Publications Warehouse
USGS Organization Coop Res Unit Leetown
Was this page helpful?