Education
- B.S., 1993, University of Wisconsin Stevens Point
- M.S., 1995, University of Wisconsin Madison
- Ph.D., 1999, University of Wisconsin Madison
Curriculum Vitae
My Google Scholar Page
Research
Aquatic Ecology, Fisheries, Hydroacoustics
My research program examines several aspects of fisheries ecology. Current projects are focused on studying the interactions between exotic and native fishes, the effects of climate change on habitat quality for cold water fishes in streams and lakes, biogeographic patterns in aquatic communities and fisheries survey design. While this group of topics is diverse, each is important for they are focused on examining the influence of human induced environmental change on aquatic communities. Fish populations are a vital source of revenue for economic interests in sport and commercial fisheries, as well as a vital link in ecosystem processes that influence water quality. Understanding linkages between aquatic species and ecosystems is vital to predicting the effects of changing the natural environment.
Recent Publications
*Schleppenbach, B.T., T.R. Hrabik, D.D. *McCann, K.B. Gran and G.G Sass. 2025. Spawning Habitat Partitioning of Sympatric Salmonid Populations in the Upper Bois Brule River, Wisconsin. Fishes 10: 506. https://doi.org/10.3390/ f ishes10100506
*Michels, NO, TR Hrabik, QC Smith, GG Sass, AF Mensinger. 2025. The effects of light intensity and water clarity on growth rates of age-0 walleye (Sander vitreus). Fisheries Research 287, 107399
*Hanson J., M. Gordon, N. Peterson, R. Lepak, C. Goldsworthy, V. Brady, T.R. Hrabik, J. Hoffman. 2025. Stable isotope analysis of western Lake Superior predatory fishes, part two: prey source contributions. Journal of Great Lakes Research 51(1), 102615
*Hanson, J., M. Gordon, N. Peterson, R. Lepak, C. Goldsworthy, V. Brady, T.R. Hrabik... 2025. Stable isotope analysis of western Lake Superior predatory fishes, part one: Trophic niche overlap. Journal of Great Lakes Research 51 (1), 102441
Stratton, K., J. George, F. Fischer, T.R. Hrabik, E.S. Dunlop, B.J. Shuter, ... 2025. Age-dependent juvenile mortality explains delayed smolting in a declining steelhead population. Journal of Great Lakes Research, 102508
*Michels, N.O., Q.C. Smith, L.S. Rogers, T.R. Hrabik, G.G. Sass, A.F. Mensinger. 2025. Visual sensitivity, foraging behavior, and success of walleye (Sander vitreus) under ecologically relevant downwelling light conditions. Environmental Biology of Fishes 108 (1), 147-160
Possamai, B., J.E. Marsden, J. Janssen, M.D. Rennie, T.R. Hrabik, ... 2024. Are lakemounts hotspots of productivity and biodiversity? Journal of Great Lakes Research 50 (6), 102440
*Michels, N.O., A.F. Mensinger and T.R. Hrabik. Effects of Light and Predator Environment on Predator Avoidance Success of Native and Invasive Benthic Prey Fishes. Ecology of Freshwater Fish. Ecology of Freshwater Fish 33 (3), e12777
*Smith, Q.C., S.L. Shaw, J.K. Raabe, G.G. Sass and T.R. Hrabik. Sport fish movement responses to littoral zone coarse woody habitat. North American Journal of Fisheries Management. 44 (2), 463-491
Conowall, P., K.M. Schreiner, J. Marchand, E. Minor, C. Schoenebeck, M. Maurer-Jones, and T.R. Hrabik. Frontiers in Earth Science 12, 1339822
Conowall, P., K.M. Schreiner, E.C. Minor, T.R. Hrabik, C.W. Schoenebeck. 2023. Variability of microplastic loading and retention in four inland lakes in Minnesota, USA. Env. Pollution. 121573.
Hrabik, T.R., *K. Olson, *T. Kaspar, M.E. Sierszen and *B.G. Matthias. 2023. The influence of conditions in Lake Superior and stream conditions on returns of migratory rainbow trout to the Bois Brule River, WI. J. Great Lakes Res. 49:506-514.
* Hrabik Graduate Student
Teaches
- BIOL 3835 Freshwater Ecology
- BIOL 4761 Ichthyology
- BIOL 5805 Fisheries Ecology and Management
- BIOL 4833/5833 Stream Ecology
- IBS 8201 Ecological Processes
Current Graduate Student Projects
- 2022- present Levi Feucht, (M.S. WRS)(Primary Adviser w/Ozersky), Winter Fish Ecology
- 2022- present Alia Benedict (Ph.D. WRS)(co-Advisor w/Ozersky), Winter Zooplankton Ecology
- 2023- present David Gallagher (Ph.D. WRS)(Primary Advisor), Biogeography of the Fish Communities of Isle Royale
- 2024- present Aiden Waterhouse (MS. WRS)(Primary Advisor), Optimal survey design for demersal coregonines
Recently Completed Graduate Student Projects
2020-2023 Danny McCann, (M.S. Integrated Biosciences) (Primary Advisor), Brule River Salmonid Niche Partitioning
2021- 2023 Andrew Helfrich, (M.S. Integrated Biosciences) (Primary Advisor), Hydroacoustic estimates of demersal prey fish abundance in Western Lake Superior
2021- 2023 Mark Ellman, (M.S. WRS)(Primary Advisor), The effects of Winterkill on Fish Communities
2021-2023 Ben Schleppenbach, (MS WRS) (Primary Advisor), Spawning habitat partitioning in Brule River Salmonid populations
2021-2024 Noland Michels, (Ph.D. Integrated Biosciences) (co-Advisor w/Mensinger), Fish predator-prey interactions under varying environmental conditions.
Recent UROP and Undergraduate Research Student Projects
- Emily Kells BURST. 2025. Hydroacoustic analyses of fish communities in nearshore Lake Superior
- Abby Stott UROP. 2024 Variability in growth and diet of Yellow Perch in Pike Lake, MN.
- Brook Harvey UROP 2023. Aquatic macroinvertebrate community of the Bois Brule River, WI. American Fisheries Society, Minnesota Chapter, St. Cloud, Minnesota, United States.
Hobbies
Fishing, Skiing, Scuba Diving, Canoeing, Camping