Research:

Aquatic Ecology, Fisheries, Hydroacoustics

My research program is presently examining several aspects of fisheries ecology. I have projects focused on studying the local and regional factors influencing the fish diversity and dispersal small and large lake ecosystems, the interactions between exotic and native fishes, and the accumulation of toxic chemicals in fish tissue. While this group of topics is diverse, each is extremely important for they are focused on examining the influence of anthropogenically induced environmental change on fish 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 fishes and the ever changing environment is vital to predicting the effects of changing the natural environment.

Recent Publications:

• Hrabik, T.R ., O. P. Jensen, S. J. D. Martell, C. J. Walters and J. F. Kitchell. 2006. Evidence for persistent diel vertical migration in the Lake Superior pelagic foodweb. In Press. Canadian Journal of Fisheries and Aquatic Sciences.

• Jensen, O. P., T. R. Hrabik, S. J. D. Martell, C. J. Walters and J. F. Kitchell. 2006. Diel vertical migration in a Lake Superior pelagic community: modeling trade-offs at three trophic levels. In Press: Canadian Journal of Fisheries and Aquatic Sciences.

• Ray, B. A., T. R. Hrabik, M. P. Ebener, O. T. Gorman, D. R. Schreiner, S. T. Schram, S. Sitar, W. P. Mattes. 2006. Variability in Lake Superior salmonine predator diet characteristics and selectivity from 1986-2001. Accepted: Journal of Great Lakes Research.
• Holbrook, B. V., T. R. Hrabik, D. K. Branstrator, D. Yule and J. Stockwell. 2006. Estimation of zooplankton biomass using hydroacoustic backscatter at two shoals in the Apostle Island region of Lake Superior. In Press: Journal of Great Lakes Research.
• Sass, G. G., J. F. Kitchell, S. R. Carpenter, T. R. Hrabik, A. Sugden-Newberry, T. K. Kratz and M. G. Turner. Fish community and food web responses to a whole-lake removal of coarse woody habitat. In Press. Fisheries
• Krueger, D. M. and T. Hrabik. 2005. Foodweb alterations that promote native species: the recovery of native cisco (Coregonus artedi) populations through management of native piscivores. Canadian Journal of Fisheries and Aquatic Sciences. 62:2177-2188.

Teaches

• BIOL 4761 Ichthyology
• BIOL 5805 Fisheries Ecology
• BIOL 1011 General Biology

Current Graduate Student Projects:

• Trent Liebich. Water quality and Atlantic salmon survival:  stream-side rearing studies on the Dennys, Pleasant and Kenduskeag Rivers.

• Allison Gamble.  The influence of habitat characteristics on trophic exchange in Lake Superior

• Matt Balge. Spatial variability in the density and size of lake superior pelagic fishes.

• Beth Holbrook. The role of mesoscale eddies in the ecology of offshore waters of Lake Superior.

Recently Completed Graduate Student Projects

• Beth Holbrook. Factors influencing success of age-0 lake trout on reef complexes in Lake Superior. M.S. Biology University of Minnesota Duluth. May 2006.

• Bradley Ray. Spatial and Temporal Variability in Prey Fish Composition and Predator Diet Characteristics in Lake Superior from 1986-2001. M.S. Biology University of Minnesota Duluth. May 2004.
• John Schwalbe. Mercury Deposition and Cycling in Northern Wisconsin Lakes and the Effect of a Decrease in Mercury Deposition on Yellow Perch (Perca Flavescens) Mercury Concentrations. M.S. Biology University of Minnesota Duluth. May 2004.
• Damon Krueger. Management applications for mitigating the negative effects of rainbow smelt on native fishes. M.S. Biology University of Minnesota Duluth. May 2003.
• Hazel Richmond (co-adviser w/A. Mensinger). Foraging mechanisms of age-0 yellow perch. M.S. Biology University of Minnesota Duluth. May 2003.
  

Recent UROP Student Projects:

• Tyler Winter. Population Assessment of Exotic Goldfish and Native Fish Specials in a Small Impoundment. 2004.

Hobbies

Fishing, Skiing, Scuba Diving, Canoeing, Camping