Prairie Research Institute

Illinois Natural History Survey

The Illinois Natural History Survey has a long history of fish and fisheries research and conservation, including one of the longest running fishing creel surveys in the world. 

Monitoring programs

INHS scientists conduct monitoring of fish and their environment in key areas across the state. The data generated by these long-term monitoring programs are critical to making informed management and conservation decisions and support Illinois’ outdoor recreation.

The Long Term Resource Monitoring (LTRM) component of the Upper Mississippi River Restoration Program assesses the health and resilience of the Upper Mississippi River ecosystem, providing a foundation for sound management actions, habitat restoration, and policy decisions. Scientists at both the Great Rivers Field Station and Illinois River Biological Station have participated in these essential monitoring activities for more than 20 years, producing a wealth of data. Fish community sampling for the LTRM program results in approximately 360 samples and 50,000 fish per year. Data taken for fish species include species identification, length, weight, and any abnormalities or deformities. The program’s purpose is to determine trends of all species from collection sites and learn how fish populations have changed over time.

The Long Term Survey and Assessment of Large River Fishes in Illinois (LTEF) has been monitoring Illinois River fish populations since 1957 and expanded in 2010 to include monitoring the Mississippi, Ohio, and Wabash Rivers along with two in-state rivers—the Kankakee and the Iroquois. This collaborative program brings together researchers from the Illinois River Biological Station and Great Rivers Field Station as well as Eastern Illinois University, Southern Illinois University, and Western Illinois University. INHS biologists survey fish species from June through October on the entire Illinois River and select reaches of the Mississippi River. The Illinois Department of Natural Resources uses these data dating back to 1957 to manage recreational fish populations.

Since 2007, scientists from the Illinois River Biological Station also have monitored fish communities and aquatic vegetation at Emiquon Preserve’s Thompson and Flag lakes on behalf of The Nature Conservancy. This work is essential in guiding and evaluating the success of restoration efforts at these two lakes, where 30 native fish species have been stocked.

INHS scientists have been studying Jordan Creek since the 1950s, amassing a well-developed database on its historical fish and invertebrate populations and water chemistry. In summer 2020, Stream Ecology Lab scientists established a long-term monitoring program for the small stream to identify changes in fish populations over the past 70 years and provide information on the current fish and macroinvertebrate communities and stream habitat.

The Illinois Conservation Reserve Enhancement Program (CREP) aims to improve water quality and enhance wildlife habitat by offering private landowners financial incentives to take highly erosive agricultural lands out of production. Since 2012, INHS Stream Ecology Lab scientists have been studying CREP’s impact on fish, macroinvertebrate, and mussel populations; water quality; and in-stream habitat quality by conducting annual monitoring throughout the Illinois and Kaskaskia river basins—watersheds that are eligible for CREP enrollment.

Lake Michigan Biological Station researchers have been studying nearshore fish communities in Lake Michigan using small-mesh gill nets since 2006. Data collected through this sampling help scientists monitor trends in abundance of nearshore prey fish, understand environmental impacts on small-bodied fish assemblages, and detect the appearance and proliferation of invasive species.

Invasive species

Illinois is among the states trying to limit the damage caused by invasive big-headed carp species due to their voracious appetites, high reproductive rates, and lack of natural predators. Bighead Carp and Silver Carp have so far not gotten farther than the Des Plaines and Joliet area thanks to methods including dams, electric barriers, and commercial fishing. INHS scientists—particularly those at the Illinois River and Kaskaskia Biological Stations—study the biology of these invasive carp species, their impact on native ecosystems and fisheries, and methods aimed at halting their spread.

Staff at the Kaskaskia Biological Station conduct annual monitoring of invasive carp reproduction within the Illinois Waterway to both provide an early warning of any increase or spread of reproductive activity further upriver and to understand how carp removals may impact the reproductive productivity of these nuisance species. In collaboration with the Illinois River Biological Station, Kaskaskia Biological Station staff also monitor the response of zooplankton communities in the Illinois River to invasive carp removals. In addition, scientists at both the Kaskaskia and Sam Parr Biological Stations investigate the risks that black carp predation pose to native mollusks and the ability of native predators to consume bighead carp and silver carp.

Staff at the Ilinois River Biological Station conduct an annual harvest of these invasive big-headed carp in collaboration with commercial fishers, removing a record-breaking 87,500 pounds of silver, bighead, and grass carp from the Mississippi River in 2021.

Nearly all research at the Lake Michigan Biological Station occurs in the context of an ecosystem fundamentally altered by invasive species. For example, LMBS annual nearshore fish community monitoring has documented the proliferation of round goby. Analyses by LMBS staff have identified diet overlap between native yellow perch and invasive alewife and round goby. However, round goby themselves are increasingly important components of yellow perch diets.

Read more about all INHS work on invasive and pest species.

Endangered and threatened species

INHS Stream Ecology Lab scientists are evaluating the distribution, abundance, and habitat preferences of two Illinois state threatened fish species—the Eastern sand darter in the Embarras River and the river redhorse in the Kankakee River. The research team aims to develop habitat suitability models for both species, which will support the Illinois Department of Natural Resources in making conservation decisions for these imperiled fishes.

INHS scientist Jeremy Tiemann and his colleagues are investigating when and where the state-threatened bigeye chub spawns to support its continued recovery in Illinois. Thought extirpated in the 1960s, the species was rediscovered in Illinois in the 1990s and is now found throughout the Vermilion River basin and in several small creeks connected to the Wabash River. However, virtually nothing is known about its reproductive behaviors—information needed to inform future conservation and management actions.

Read more about all INHS work relating to endangered and threatened species.

Fish & fisheries ecology

Many INHS scientists study the ecology of fish and fisheries.

Population demographics

Scientists at the Kaskaskia, Ridge Lake, and Sam Parr Biological Stations conduct research addressing questions about fish recruitment variability, reproductive success, and larval ecology. Focal taxa for these studies include centrarchids, such as largemouth bass, bluegill, and crappie species, and the clupeid gizzard shad.

The Sport Fish Ecology Lab, led by Jeffrey A. Stein, estimates the relative abundance, distribution, size structure, and age structure of gars and Bowfin in major Illinois watersheds. Data from these studies will be one of the first to document baseline population parameters of these ancient species and can be used to compare population parameters across watersheds in the state. The Illinois River Biological Station and Great Rivers Field Station are among the partners on this work, which draws on data from the LTEF monitoring program.

Fisheries management

INHS scientists conduct research on economically important, inland recreational fisheries in Illinois. This includes investigating the ecological and human dimensions dynamics affecting the sustainability and impacts of fishery exploitation, as well as the efficacy of management interventions such as stocking practices and harvest regulations.

Scientists at the Kaskaskia, Ridge Lake, and Sam Parr Biological Stations integrate analyses of ecological and sociological factors into their research on experimental harvest regulations and habitat enhancement of urban fisheries in the Cook and DuPage county forest preserve districts. These projects are conducted in collaboration with the INHS Human Dimensions Research Program.

In addition, the Ridge Lake Biological Station, located inside Fox Ridge State Park, conducts one of the longest running fishing creel surveys in the world. Anglers fishing at the lake during open times each summer can participate in the survey; their fish are measured and weighed, providing data for a number of ongoing studies on bluegill, largemouth bass, and muskie populations. Since 1985, the Lake Michigan Biological Station also has worked with the Illinois Department of Natural Resources to conduct creel surveys of recreational pedestrian and boater anglers along the Illinois shoreline. This generates valuable data about fishing efforts, harvest, and distribution of important fish species.

Scientists at the Lake Michigan Biological Station also study the population dynamics of yellow perch, which is both a significant sport fish for anglers and an important part of the Lake Michigan ecosystem. Age data collected by examining yellow perch otoliths and anal fin spines are used by LMBS staff to develop estimates of growth and year-class strength, contributing to further understanding of how changes in yellow perch ecology affect harvest.

Stream Ecology Lab scientists are monitoring smallmouth bass populations in the Mackinaw and Vermilion rivers, with a focus on providing information needed to address low abundances in the Mackinaw River. Their analyses will support efforts by Illinois Department of Natural Resources to improve management of smallmouth bass fisheries.

Movement and habitat selection

Researchers in the Sport Fish Ecology Lab are investigating the movement of gars, seeking insights about their spatial ecology, habitat use, and migration patterns.

The construction of artificial reefs in the nearshore environment for shoreline protection has created a unique opportunity for researchers at the Lake Michigan Biological Station to quantify fish usage and ecological succession in these newly created habitats. LMBS researchers measure biological activity on these reefs using a combination of gill nets and SCUBA surveys, which provide data on the abundance and diversity of the fish and benthic invertebrates that are using these new habitats. These data will help researchers understand how fish and invertebrate communities may respond to changing conditions in Lake Michigan, including changing lake levels and increased erosion, due to changes to the climate cycle in the Great Lakes.

Researchers at the Kaskaskia, Ridge Lake, and Sam Parr Biological Stations study the effects of habitat enhancements in reservoirs designed to aggregate fishes and increase fish productivity. These habitat enhancement studies are conducted at various spatial scales, from reservoir coves to whole-lake manipulations, and quantify responses at various levels, from fish behavior to population demographics to food web effects.

Scientists at the Kaskaskia Biological Station have also used acoustic telemetry to study habitat use and movement ecology of muskellunge newly released into Lake Shelbyville.

Community ecology & food webs

Scientists at the Kaskaskia, Sam Parr, and Ridge Lake Biological Stations are evaluating trophic dynamics in aquatic communities, predator-prey interactions, growth, optimal foraging, and bioenergetics. These investigations include novel predator-prey interactions resulting from biological invasions, ecomorphological factors shaping differential performance of sympatric crappie species, and the role of behavioral syndromes in trophic niche partitioning. In addition, Kaskaskia Biological Station researchers collaborate with scientists from the Illinois Sustainable Technology Center to investigate patterns of larval fish ingestion of microplastic pollution within the Illinois River.

Researchers at the Lake Michigan Biological Station sample the lake’s zooplankton, benthic invertebrates, and small-bodied fish to evaluate the impact of prey quantity and quality on fish diets and growth. In addition to examining stomach contents, LMBS scientists also analyze fatty acid composition as a means of tracing prey sources and mapping food webs

Fish collection

The INHS Fish Collection contains more than 890,000 catalogued specimens, which makes it about the 15th largest collection of preserved fishes in North America. Represented are about 170 families and over 2,500 species. This includes a large number of old specimens, many of which were collected in the late 1800s. Data from the fish collection can be searched online.

Read more about all INHS biological collections.


In coordination with the Illinois Department of Natural Resources, INHS staff manage the I Fish Illinois website, which offers all the information anglers need to prepare for and enjoy a successful fishing season in Illinois, including places to fish, fishing with the family, fishing programs, licensing regulations, fish stocking, and much more.

Published by the University of Illinois Press in 2022, An Atlas of Illinois Fishes: 150 Years of Change presents a “visually spectacular guide to every fish species in Illinois.”

List of Illinois fishes.