Midwest Fish & Wildlife Conference 2018

AUTHORS. Phillip Oswald, Bemidji State University; Dr. Andrew Hafs, Bemidji State University; Tony Kennedy, MNDNR; Jake Graham, Boise State University

ABSTRACT. The Tamarac River, a major tributary to the Red Lakes, Minnesota, drains one of the largest peat bogs in the lower 48 states and thus experiences low dissolved oxygen at times.  The river hosts a substantial Walleye (Sander vitreus) spawning migration but it is largely unknown how the potential anoxic bog water affects walleye reproductive success each year and subsequent year class strength. Walleye reproductive success is of critical interest for the Red Lakes as this system is maintained entirely by natural reproduction and supports robust commercial and recreational fisheries.  Abiotic factors such as dissolved oxygen, temperature, and stream discharge are known to influence Walleye reproductive success and potential recruitment and these factors vary annually. Fyke nets were set from 2014-2017 to assess the relative abundance of adult Walleye spawning in the river. In 2017, a Jolly-Seber abundance estimator was used to assess the magnitude of the spawning migration. Larval drift nets were set in 2014, 2016 and 2017, to assess fry out-migration in the Tamarac River. Larval drift nets were not set in 2015 due to low water levels and insufficient discharge. Non-linear regression models were run to assess the relationship between larval Walleye density and dissolved oxygen, temperature, and stream velocity. Establishing relationships between abiotic factors and Tamarac River larval Walleye density will help managers better understand the importance of the Tamarac River to overall Walleye production in the Red Lakes.Keywords: Freshwater Fish - Walleye, River/Stream, Wetland