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Monday, January 29 • 2:20pm - 2:40pm
WALLEYE: Identifying Recruitment Bottlenecks for age-0 Walleye in Northern Wisconsin Lakes

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AUTHORS. Daniel Isermann, USGS-Wisconsin Cooperative Fishery Research Unit; Jason Gostiaux, Fisheries Analysis Center, University of Wisconsin-Stevens Point, Hadley Boehm, Wisconsin Department of Natural Resources, Joseph Hennessy, Wisconsin Department of Natural Resources, Gretchen Hansen, Minnesota Department of Natural Resources

ABSTRACT. Natural recruitment of walleye has declined in some northern Wisconsin lakes where adult walleyes were still present in sufficient numbers to produce year classes based on previous data. Initial assessments on 4 lakes suggested that a recruitment bottleneck was occurring at or before the larval stage. During 2016 and 2017, we conducted age-0 walleye sampling on 13 northern Wisconsin lakes with two different recruitment histories (declining = D-NR, sustained = S-NR) to determine if the timing of a recruitment bottleneck was consistent among D-NR lakes. We also assessed whether abiotic and biotic variables differed between lakes with different recruitment histories. Age-0 walleye were collected after the larval stage in six of seven S-NR lakes but were not observed at any stage in the remaining S-NR lake. Age-0 walleye were collected after the larval stage (summer gill netting and fall electrofishing) in only one of six D-NR lakes, but in very low numbers. Our data suggests a recruitment bottleneck occurs at or before the larval stage in many D-NR lakes. We are also assessing diets of larval walleyes and examining whether zooplankton communities differ among lakes in each recruitment category during the period when larval walleyes are present.

Monday January 29, 2018 2:20pm - 2:40pm CST