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Fisheries Research

Four small tubes containing fish scales collected from harvested fish at the Northern Highland Fishery Research Area.

Our team of fisheries research scientists, biologists and technicians produce objective, applicable science for the DNR that helps inform fisheries management decisions. Staff are engaged in high-priority research projects related to Wisconsin sport fishes, with specialties including applied fisheries management and ecology, quantitative stock assessments, fish habitat, propagation science and population dynamics.

The fisheries research team works together to cover the diversity of Wisconsin's aquatic habitats and species with three stations across the state: Escanaba Lake Research Station in the Northern Highland Fishery Research Area (NHFRA), the Science Operations Center in Madison, and the DNR Service Center and Tommy G. Thompson State Hatchery in Spooner. The team collaborates with anglers, universities, state hatcheries, tribal partners and conservation groups across the state and country to help meet fisheries research needs. 

Northern Highland Fishery Research Area Studies

The Northern Highland Fishery Research Area (NHFRA) provides a suite of experimental lakes in the Boulder Junction area for the long-term purposes of monitoring angler behaviors, fish population dynamics, and ecosystem-scale studies to benefit fisheries across Wisconsin. Numerous studies have been conducted in the NHFRA over its long history, including fisheries regulations, effects of angler habits on fish populations, fish biology and fish species interactions. In addition to the regular compulsory creel, seasonal field surveys and ongoing monitoring efforts, NHFRA staff are currently conducting the following research projects: 

A fallen tree trunk near the shore provides micro-habitats for fish species

Fish Production with Coarse Woody Habitat Additions

Goal: Measure the effects of adding coarse woody habitat on the fish-carrying capacity of Wisconsin lakes.


Two walleye in a net

Assessing Sportfish Angler Dynamics in Northern Wisconsin

Goal: Determine if walleye angler effort has changed in response to walleye population declines and if that effort has shifted to non-walleye sportfish.


Fish Community Production Distribution in Walleye Lakes

Goal: Determine how fish production is being (re)distributed in declining walleye lakes compared to walleye lakes that have remained stable in recent years.


Statewide Fisheries Research Studies

Fisheries scientists in the Office of Applied Science also work together on projects across the state, from the cold waters of Lake Superior to the streams and lakes of southern Wisconsin. Staff work with collaborators and stakeholders to better understand and meet research needs and are currently working on the following projects:

Survival and Fitness of Stocked Brook Trout

Goal: Calculate the relative stocking success of three generations of brook trout produced by hatcheries.


Beaver swimming in a lake

Beaver Influences on Trout Populations

Goal: Examine how beavers affect coldwater streams and trout populations in ecoregions and beaver management zones across Wisconsin.


Juvenile musky in a holding tank, waiting to be released into Wisconsin lakes.

Muskellunge Age and Growth Study

Goal: Evaluate non-destructive means for determining muskellunge age and growth, as well as determine the effects of catch-and-release on muskellunge mortality and size structure.


An icy lakeshore in northern Wisconsin.

Spawning Phenology

Goal: Test for phenological shifts in the spawning of sport fishes around Wisconsin, understand what may be driving these shifts and determine their implications for recruitment.


DNR staff holds a beautiful trout, picked from a bucket below.

Temporal Trends in Trout Populations

Goal: Measure environmental conditions over time to help understand how and why trout populations vary in response to water temperature, stream flow and other habitat variables.


Chinook Salmon

Reassessing the Predator-Prey Balance on Lake Michigan

Goal: Reassess the predator-prey balance in Lake Michigan to account for recent changes in the prey fish community and associated shifts in feeding dynamics.


A large, vivid bluegill caught during a survey.

Assessing Effects of Alum Treatments on Panfish Growth and Recruitment

Goal: Evaluate the influences of aluminum sulfate treatments for Big Round Lake on panfish size, growth and abundance.


Three bluegill fish in a white bucket.

Panfish Responses to Angling and Predation

Goal: Assess trends in Wisconsin's panfish populations (abundance and size structure) in response to angler exploitation and predator management.


Steelhead from the Brule River

Age-Structured Stock-Recruitment Assessment of Steelhead

Goal: Assess steelhead biological reference points like spawning stock sizes and sustainable yield in the Brule River and western Lake Superior.


Creel station staff explain the NHFRA permit.

Evaluating Creel Survey Efficiencies for Wisconsin's Recreational Fisheries

Goal: Improve creel survey efforts by combining a model-based approach and reallocation of sampling efforts across space and time.


Scientific Consulting

In addition to the research projects above, the Office of Applied Science also provides consultation services to the Division of Fish, Wildlife and Parks. These consultation services are often in the form of population analyses, scientific design or analysis services and consultation on management issues to ensure the best possible scientific information is available to decision-makers.

The open dialogue between the Office of Applied Science and the Bureaus of Wildlife Management and Fisheries Management helps drive our research foci so that research directly fills the research needs of decision-makers.  

Publications and reports

View a list and links to our recent journal publications and reports. For NHFRA-specific peer-reviewed papers, please see NHFRA Publications.