Department of Biology
THOMAS HRABIK, Associate Professor

B.S., 1993, University of Wisconsin Stevens Point
M.S., 1995, University of Wisconsin Madison
Ph.D., 1999, University of Wisconsin Madison

Office: 11 SSB
Phone: 726-7626

Curriculum vitae


Aquatic Ecology, Fisheries, Hydroacoustics

My research program is presently examining several aspects of fisheries ecology. I have projects focused on studying the interactions between exotic and native fishes, the effects of changing climate on habitat quality for cold water fishes and nutrient regeneration-translocation by vertically migrating fauna in the recovering food web of Lake Superior. 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

  • Issac, E.J.*, T.R. Hrabik, J.D. Stockwell, A.E. Gamble, and D.L Yule. 2012. Prey selectivity in the Lake Superior food web. Journal of Great Lakes Research. 38:326-35.
  • Warner, D.M., R.C. Claramunt, J.S. Schaeffer, T. Hrabik, B. Pientka, D. Yule, L. Rudstam, J.S. Holuszko and T.P. O'Brien. 2012. Relationship between mid-water trawling effort and catch composition variability in large lakes dominated by alosines, osmerids and coregonines. Risheries Research. 123:62-69.
  • Ahrenstorff, T.D.*, O.P. Jensen, B.C. Weidel, B. Mendsaikhan, and T.R. Hrabik. 2012. Abundance, spatial distribution, and diet of endangered Hovsgol grayling (Thymallus nigrescens). Environmental Biology of Fishes. DOI: 10.1007/s10641-011-9961-5.
  • Gamble, A.E.*, T.R. Hrabik, J.D. Stockwell, D.L. Yule. 2011. Trophic connections in Lake Superior I: the offshore foodweb. Journal of Great Lakes Research 37:541-549.
  • Gamble, A.E.*, T.R. Hrabik, J.D. Stockwell, D.L. Yule. 2011. Trophic connections in Lake Superior II: the nearshore foodweb and comparisons to the offshore foodweb. Journal of Great Lakes Research 37:550-560.
  • Ahrenstorff,T.D.*, T.R. Hrabik, J.D. Stockwell, D.L. Yule, and G.G. Sass. 2011. Seasonally dynamic diel vertical migrations of Mysisdiluviana, coregonine fishes, and siscowet lake trout in the pelagia ofWestern Lake Superior. Transactions of the American Fisheries Society140:1504-1520.
  • Liebich, T.A.*, S.D. McCormick, D. Kircheis, K. Johnson, R. Regal, T.R. Hrabik. 2011. Water chemistry and its impacts on the physiology and survival of Atlantic salmon (Salmo salar) smolts in eastern Maine, USA. J.Fish.Biol. 72:502-519.
  • Jensen, O.P., S. Hansson, T. Didrikas, J.D. Stockwell, T.R. Hrabik, T. Axenrot and J.F. Kitchell. 2011. Foraging and bioenergetic constraints on diel vertical migration: field observations and modeling of Baltic Sea young-of-year herring (Clupea harengus). J. Fish.Biol. 78:449-465.

* Graduate Student papers


  • BIOL 4761 Ichthyology
  • BIOL 5805 Fisheries Ecology
  • BIOL 2802 Ecology Lab
  • IBS 8201 Ecological Processes

Current Graduate Student Projects

  • Tyler Ahrenstorff (Ph.D., Integrated Biosciences) (Primary Advisor). Thesis Spatial, temporal and seasonal patterns in distribution and trophic interactions in pelagic foodwebs. Expected completion date: Spring 2013.
  • Emily Heald
  • Kirk Olson (M.S., Integerated Biosciences) (Primary Advisor). Thesis – Niche partitioning and diet characteristics of Arctic grayling, Hovsgol grayling and sharp-nosed lenok in Mongolia. Expected completion date: Spring 2013.
  • Trevor Keylor (M.S., Integrated Biosciences) (co-advisor w/Mensinger). Thesis - TBA.

Recently Completed Graduate Student Projects

  • Samantha Mueller (M.S., Integrated Biosciences )(co-advisor w/Branstrator). Thesis - Nutrietnt regeneration by zooplankton in Lake Superior: Summer 2012.
  • Tyler Kasper (M.S., Integrated Biosciences) (Primary Advisor). Thesis - Factors influencing migratory rainbow trout recruitment in Lake Superior. Spring 2012.
  • Edmund Issac. MSc. Evaluation of Mysis relicta as a keystone species in the food web of Lake Superior 2011
  • Allison Gamble. Ph.D. The influence of habitat characteristics on trophic exchange in Lake Superior 2011
  • Beth Holbrook. Ph.D. The role of mesoscale eddies in the ecology of offshore waters of Lake Superior. 2011

Recent UROP Student Projects

  • Logan Jacobson.  Seasonal changes in zooplankton species composition and distribution in Crystal Lake, WI.


Fishing, Skiing, Scuba Diving, Canoeing, Camping

© 2014 University of Minnesota Duluth
The University of Minnesota is an equal opportunity educator and employer.
Last modified on 10/22/13 09:16 AM
University of Minnesota Campuses
Crookston | Duluth | Morris
Rochester | Twin Cities | Other Locations