Comparing AWSSI and Traditional Winter Metrics for Predicting Overwinter Survival of Juvenile Walleye (Sander vitreus)

Authors

• Camille N. Shifrin, University of Nebraska-LincolnFollow

First Advisor

Jessica Corman, School of Natural Resources

Second Advisor

Lindsey Chizinski, School of Natural Resources

Date of this Version

5-2026

Document Type

Thesis

Citation

Shifrin, C. N. (2026). Comparing AWSSI and Traditional Winter Metrics for Predicting Overwinter Survival of Juvenile Walleye (Sander vitreus). Undergraduate Honors Thesis. University of Nebraska-Lincoln. March 2026.

Comments

Copyright Camille Nicolette Shifrin, 2026. 

Abstract

Winter conditions are an important driver of recruitment variability in freshwater fishes, yet winter severity is often characterized using single climate metrics. These simplified approaches may not capture the cumulative stress experienced by fishes during winter. The Accumulated Winter Season Severity Index (AWSSI) integrates multiple components of winter climate and may therefore provide a more biologically relevant indicator of overwinter survival. In this study, we compared AWSSI with traditional winter severity metrics to explain interannual variation in overwinter survival of juvenile Walleye (Sander vitreus) in Harlan County Reservoir, Nebraska. Model comparisons using Akaike’s Information Criterion (AIC) indicated that models incorporating AWSSI provided the strongest relative support. However, relationships between winter severity and juvenile survival were weak and not statistically significant, and overall explanatory power was modest, suggesting additional ecological processes also influence juvenile survival. These results indicate that winter conditions may influence survival indirectly and should be considered alongside broader ecological drivers. Improved representation of winter severity may offer potential utility for recruitment forecasting and inform fisheries management as winter conditions continue to change.