Sass GG, Shaw SL, Rooney TP, Rypel AL, Raabe JK, Smith QC, Hrabik TR, Toshner ST. 2019. Coarse woody habitat and glacial lake fisheries in the Midwestern United States: knowns, unknowns, and experiment to advance our knowledge. Lake Reserv Manage. 35:382–395. Coarse woody habitat (CWH) additions have increased in popularity in glacial lakes (i.e. kettle lakes) of the Midwestern United States. However, most enhancements have not been treated as deliberate experiments to test for fish and aquatic ecosystem responses. Whole-lake CWH removal studies have shown reductions in fish growth rates, declines in forage fish abundance, and behavioral changes. Whole-lake CWH addition studies have shown improved reproductive output of certain fishes, increased availability and diversity of prey available to fishes, and influenced behavior and habitat use. Key uncertainties identified in previous CWH addition studies include: (1) Does CWH increase fish production? (2) Does CWH influence certain fish species differently? (3) Does CWH influence fish populations in larger lakes than previously studied? (4) Does CWH influence fish populations over longer periods of time? In 2015, we began a whole-lake CWH addition experiment on a northern Wisconsin lake aimed to address these uncertainties. Sanford Lake maintains a low productivity fish community and supports fishes not generally studied before in the context of CWH. Fish population dynamic/behavior and aquatic ecosystem response variables will be monitored, and tree drop CWH additions are slated for 3 phases over 20 yr. We introduce the Sanford Lake experiment and provide recommendations for expectations and the implementation of CWH additions in inland glacial lakes. Given the reliance of north-temperate inland glacial lake fisheries on allocthonous sources of energy and negative influences of lakeshore residential development on CWH, we hypothesize that CWH addition may contribute to maintaining or enhancing fish production.
Bibliographical noteFunding Information:
Special thanks to Tim Hanson, Jerry Geiger, and Dairymen?s Inc., for allowing us access to Sanford Lake and for their logistical and field support. We also thank Joe Nohner and the Midwest Glacial Lakes Partnership for sponsoring a symposium at the Midwest Fish and Wildlife Conference, Milwaukee, Wisconsin, 2018, where this work was first presented and for organizing this special issue in Lake and Reservoir Management. We also acknowledge the editor-in chief, associate editor, and two anonymous reviewers for providing constructive comments on an earlier draft of this manuscript. This research was supported by the US Fish and Wildlife Service, Federal Aid in Sportfish Restoration funding to the Wisconsin Department of Natural Resources, project F-95-P, FHCW.
- Coarse woody habitat
- fish production
- inland lakes
- tree drops
- “fish sticks”