Factors Effecting Growth Trajectory of Walleye in Northern Wisconsin Lakes

Abstract

Understanding population dynamics of sympatric fishes can be important for management. Walleye Sander vitreus are an important recreational species and a top predator in the systems they inhabit. Walleye growth can be highly variable among lakes suggesting that within-lake factors such as prey availability and quality are important. A statewide assessment of Cisco Coregonus artedi, an important prey species for Walleye, was recently conducted in Wisconsin lakes to better understand the status of this important species. We used data from a long-term standardized Walleye survey program (Ceded Territory of Wisconsin; CTWI) and the recent Cisco assessment to determine Walleye growth trajectories among lakes with and without Cisco. Analysis of the data from 87 populations of walleye across the CTWI revealed that female walleye reach greater asymptotic lengths in lakes where Cisco were detected, while male Walleye asymptotic length did not differ among lakes with and without Cisco detections. Common Walleye minimum length limits, 15 and 18 inches, were reached 0.6 and 0.9 years earlier in lakes with Cisco detections. Yellow Perch Perca flavescens, another common prey item for Walleye, mean length was significantly lower than lakes without Cisco. This could further enhance Walleye growth as they generally select for prey \u3c 130 mm. Therefore, managing to maintain Cisco habitat in these lakes could help ensure fast growth and trophy potential of Walleye in these systems