Fisheries research

The program's researchers and support staff ensure that good science informs DNR fisheries management decisions every day.



Research groups

Populations & fish community ecology

Research focuses on population assessment and fish community dynamics. Researchers in this group also study how climate, invasive species and other systems changes alter populations and communities.


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John HoxmeierSt. PaulPopulation dynamics, competition, predator/prey relationships, fish age and growth, reproductive life history
Tyler AhrenstorffBrainerdBioenergetics, hydroacoustics and predator-prey interactions.
Beth HolbrookBrainerdHydroacoustics, pelagic fish communities, early life stages, bioenergetics, geographic information systems and spatial variability
Loren MillerSt. PaulGenetics, stock identification, genetic tagging, parentage analysis and reproduction studies, hybrid identification, forensics, fitness evaluations, stocking evaluations


Delivers technical information to resource managers and policy makers on fish habitat issues. The group develops expertise from past studies and existing information, in addition to implementing new research targeted at filling important information gaps. Because technical information on fish habitat spans a wide array of sciences such as limnology, aquatic botany, hydrology, landscape ecology and climate science, a key role of the group is to synthesize this knowledge into a form usable by managers, policy makers and the public.


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Pete JacobsonPark RapidsWatersheds, thermal habitat, water quality, climate change adaptation
Doug DietermanLake CityStream morphology, cold & warm water streams, large rivers, watersheds, water quality, agriculture, hydrology & connectivity, long-term monitoring
Donna DustinDetroit LakesGeographic information systems, nearshore habitat, aquatic plants, woody structure, shoreline development, cumulative effects
Brian HerwigBemidjiEcology of shallow lakes, food web dynamics, ecosystem ecology, stable isotopes, landscape-scale approaches, invertebrate ecology, feeding ecology of fish & bioenergetics
Heidi RantalaDuluthEcosystem ecology, lake ecology, landscape ecology, lower trophic levels, food webs, secondary production

Applications & human dimensions

Focuses on addressing traditional fisheries management questions through experiments and reviews of existing information. These questions often revolve around stocking and regulations. We evaluate stocking strategies and regulations to determine which actions are most likely to succeed. In doing so, we continually learn more about how lakes and streams function and can use this new information to determine the best management options for other lakes and streams. The learning process includes refining sampling tools and techniques to get better answers. Finally, we learn about angler behavior and attitudes so that we can figure out how anglers will adjust to new stocking strategies or regulations.


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Patrick SchmalzDuluthStock assessment, population dynamics, large lake fisheries, regulation evaluation
Bethany BethkeDuluthPopulation dynamics interactions with invasive species and climate change; applying stable isotope analysis to species interactions; range expansion of bass species
Will FrenchSt. Paul, Warner RoadSentinel lakes/long term monitoring, trophic ecology, large rivers, trout streams, stable isotopes
Dale LogsdonWatervillePopulation estimation, population dynamics, recruitment, marking methods, age & growth
Tim MartinSt. Paul, Central OfficeLong term monitoring data, GIS and mapping, data management, angler behavior
Mike McInernyGlenwoodAssessment methodology, age & growth, Centrarchids
Jeff ReedGlenwoodLong-term monitoring, angler dynamics and human dimensions, spawning and nursery habitats, Centrarchids, food webs, science communication
Steve ShroyerWatervilleMark-recapture methods, Program MARK, Ictalurids, large river fish sampling, radio and acoustic telemetry, age & growth, winterkill/reverse aeration
Casey SchoenebeckGlenwoodSentinel Lakes/long-term monitoring, trophic dynamics, early life history


Melissa Treml, fisheries research manager, St. Paul
[email protected]
tel. 651-259-5231
fax 651-297-4916