Cooperative Research Units
Education, Research And Technical Assistance For Managing Our Natural Resources
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Wild juvenile salmonid abundance and outmigration in Wisconsin tributaries to Lake Michigan


July 2015 - December 2018


Introduced salmonids (i.e., chinook and Coho salmon, rainbow and brown trout) support important recreational fisheries within the Lake Michigan ecosystem. These fisheries are primarily supported by stocking. However, some natural reproduction is known to occur within some tributary systems. Specifically, anadromous rainbow trout (i.e., steelhead) stocked into Lake Michigan are known to exhibit an adfluvial life history, migrating up tributaries for spawning. Wild offspring have been encountered in some of these tributaries, but it is not known whether these fish successfully outmigrate from these streams into larger tributaries or Lake Michigan. The primary objectives of our research are to determine if: 1) abundance of wild age-0 salmonids (primarily steelhead) varies among selected streams in relation to available habitat; 2) wild age-0 salmonids successfully outmigrate from Wisconsin tributaries into Lake Michigan or into larger tributaries and 3) potential bottlenecks related to stream temperature or annual flow regimes prevent successful outmigration from some streams. We will also compare mark-recapture methods used to estimate wild age-0 salmonid abundance to determine if a single sampling event following stocking of marked fish yields similar estimates to estimates derived from multiple sampling events.

Research Products and Activities

Peer Reviewed Publications

  • Wegleitner, E.W, and D.A. Isermann. 2017. Comparison of two viewing methods for estimating largemouth bass and walleye ages from sectioned otoliths and dorsal spines. North American Journal of Fisheries Management 37:1304-1310. DOI

Current Staff

Federal Staff: 95

Masters Students: 239

Phd Students: 144

Post Docs: 55

University Staff: 239

5 Year Summary

Students graduated: 670

Scientific Publications: 1897

Presentations: 4193



Funding Agencies

  • Wisconsin Department of Natural Resources


Cooperative Research Units Program Headquarters Cooperators

  1. U.S. Geological Survey