2025 Midwest Fish & Wildlife Conference

AUTHORS:  Seth J. Fopma, Iowa Department of Natural Resources

ABSTRACT:  Suitable overwintering habitat is considered to be a limiting factor for Centrarchids in the Upper Mississippi River (UMR). Lock and dam construction in the 1930’s greatly increased total aquatic area of the UMR and provided deep backwater areas favorable to Centrarchid populations; however, sediment deposition has reduced the quantity and quality of deep water habitats presumably limiting overwinter survival. The U.S. Army Corps of Engineers’ Upper Mississippi River Restoration Program (UMRR) initiated a Habitat Rehabilitation and Enhancement Project (HREP) project on Pool 12 of the UMR in 2013. Project objectives included the development of approximately 63 acres of suitable overwintering habitat in four backwater lakes found throughout Pool 12 where insufficient overwintering habitat was thought to limit Centrarchid survival. Habitat restoration in Tippy Lake occurred during 2017 with the goal of increasing the availability of habitat suitable for overwinter survival. Pre-project telemetry efforts utilized radio telemetry during the winter of 2014-2015 to estimate habitat utilization distribution of crappie (n = 50). Telemetry efforts resumed during the winter of 2023/2024 to assess crappie habitat utilization post-project. Relatively recent advances in acoustic telemetry technologies offered researchers the opportunity to compare telemetry methods during the post-project evaluation. Radio (n = 20) and acoustic (n = 20) tags were implanted into crappie November 15-16, 2023 and fish were tracked through the first week of June 2024. Habitat utilization distributions pre and post-project were similar when evaluated using data generated from radio telemetry efforts but differed from estimates calculated using acoustic telemetry data.

AUTHORS: Mark Pegg, University of Nebraska-Lincoln; Victoria Davis, University of Georgia; Martin Hamel, University of Georgia; Dave Buckmeier (retired), Texas Parks and Wildlife Department ; and Jeff Koch, Kansas Department of Wildlife and Parks

ABSTRACT: Accurate determination of fish age from hard structures is a cornerstone of informing fisheries conservation and management. Further, the need to validate age estimates from calcified structures is commonly identified by scientists faced with the task of age estimation. Appeals for ensuring accuracy of age estimates have been pervasive in recent times, but unfortunately, natural resource agencies charged with managing stocks do not possess resources to build large collections of structures from known-age fish. To circumvent these challenges, we set out to develop a publicly available, web-based repository of digital images of known-age reference structures for North American freshwater fishes. In spring of 2023, we began collecting reference structures (e.g., otoliths, spines, fin rays, etc.) containing annual or daily age confirmation. At website launch (August 2024), calcified structures of known-age fish have been processed and imaged for five freshwater species: Largemouth Bass, American Shad, Muskellunge, Striped Bass, Channel Catfish, and Lake Sturgeon with over 500 images available for public reference. Images have been uploaded onto our new website, www.fishage.org, and will continuously be updated to include additional species, featuring metadata (e.g., source of structure, preparation method), multiple age classes and geographical data. metadata (e.g., source of structure, preparation method) and new structures.  We envision this application being used for training new personnel, quality control, and to advance the science of age estimation.

AUTHORS: Kayla Lenz, Great Lakes Indian Fish and Wildlife Commission; Douglass Keiser, Great Lakes Indian Fish and Wildlife Commission; Aaron Shultz, Great Lakes Indian Fish and Wildlife Commission; Adam Ray, Great Lakes Indian Fish and Wildlife Commission; Mark Luehring, Great Lakes Indian Fish and Wildlife Commission

ABSTRACT: The Anishinaabe worldview teaches us that all things that western society considers to be “resources” are, in fact, living beings that take care of one another as well as us humans. As human disturbances and climate change (Aanji-bimaadiziimagak o'ow aki; loosely, “a changing world”) alter the habitat of the creatures that care for us, we have a responsibility to, in turn, do what we can to help them. The Minocqua Chain of Lakes in the 1842 Ceded Territory in northern Wisconsin are among the most popular destinations for boating and angling in the state. For Minocqua Chain ogaa (walleye Sander vitreus), poor recruitment to the year-1 age class (likely due to a combination of factors) has resulted in a decrease in adult abundance over time. Observations of age-0 and age-1 walleye have been decreasing for years, reaching an all time low in the mid 2000’s. In an effort to alleviate this decrease, the Minocqua chain of lakes have been stocked annually with thousands of fingerling ogaawag since 2013. However, management and population recovery efforts are rarely effective if the focus is placed solely on the species of interest. As part of a holistic approach to assess the effects of changing ecosystems on the Minocqua Chain, we identified juvenile habitat for several fish species in two lakes in this system: Minocqua and Kawaguesaga Lakes. This was accomplished via snorkeling and electrofishing surveys of the two lakes to locate, map, and characterize juvenile fish habitat across all observable species. “Juvenile habitat” included hatching, feeding, and nursery habitat for age-0 and age-1 fish of any species. These surveys identified hotspots of juvenile fish activity that may be critical to protecting aquatic life of all types in the Minocqua Chain. Juvenile fish were observed to occupy about 12.87 km (48.1%) of Minocqua’s shoreline and 11.24 km (63.5%) of Kawaguesaga’s shoreline. While there were strong territorial boundaries between the ranges of juvenile predator species in Minocqua, they were more likely to cohabitate in Kawaguesaga. In both lakes, juvenile fish of all species were likely to be concentrated in areas of the lakes with little to no shoreline development. The results of these surveys may be used to inform fisheries stewardship/management plans, designate critical habitat for these species, and improve shoreline and up land use policies for this beloved waterway.

AUTHORS: Justin Lombardo, University of Illinois Urbana-Champaign; Cory D. Suski, University of Illinois Urbana-Champaign; David P. Philipp, Fisheries Conservation Foundation; Joel Zhang, Carleton University; Joseph Parkos, Illinois Natural History Survey; Steven J. Cooke, Carleton University; Jeffrey A. Stein, Illinois Natural History Survey

ABSTRACT: Spring fishing for spawning black bass is a controversial topic. The aggressive behaviors exhibited by nesting males increases their susceptibility to angling, and should a nesting bass be removed by an angler, all offspring in that nest can be consumed by predators. Over time, this has potential to negatively impact populations, which may suggest the need for regulatory protection for nesting males. Unfortunately, long-term studies that track changes in black bass populations due to angling during the spawn have not been conducted, precluding our ability to make definitive conclusions about the impact on populations. The objective of this study was to quantify how reproductive and behavioral characteristics of spawning black bass in lakes Charleston and Opinicon in southern Ontario have changed due to angling pressure over a 32-year period compared with two control populations that have not received angling pressure. For this, nesting surveys were conducted during two sampling periods by snorkeling along the littoral zone in all four lakes to observe the mating success of nesting males. After snorkeling, nests were angled with 15 standardized casts to quantify susceptibility to angling. Results show that, from the 1990s to 2020s, there was no significant change in mating success in any of the studied lakes. The percentage of strikes on the first cast, however, significantly decreased in smallmouth bass in lakes Charleston and Opinicon, with no significant decreases in the control lakes. Similarly, in lakes Charleston and Opinicon, the percentage of strikes on any cast decreased in largemouth bass, with no significant changes in the control lakes. Results suggest that fisheries induced evolution may be negatively influencing black bass behavior and eroding their response to angling. Results will be further discussed in the context of protected areas to mitigate the consequences of angling.

AUTHORS: Benjamin J. Schall, South Dakota Department of Game, Fish and Parks; David O. Lucchesi, South Dakota Department of Game, Fish and Parks; Keith E. Schwartz, South Dakota Department of Game, Fish and Parks; Alison A. Coulter, South Dakota State University; Steven R. Chipps, USGS Cooperative Fish and Wildlife Unit, South Dakota State University

ABSTRACT: Changes to aquatic habitats owing to climate change can impact fish populations. Warming temperatures combined with changes in the magnitude and frequency of precipitation events have resulted in more frequent flooding and increased river flows in portions of the upper Great Plains. The impact of changing flow and increased water temperature on fishes in these systems is not well understood. Therefore, this study was designed to evaluate the impacts of changing water levels and temperature on Channel Catfish and Flathead Catfish growth and condition. Channel Catfish were collected in eastern South Dakota from the James River from 2017-2024 and the Big Sioux River from 2021-2024. Flathead Catfish were collected from the James River in 2018 and 2022-2024. Growth increments were measured from the three most recent pectoral spine annuli, and lengths-at-age were back-calculated. A series of Bayesian generalized linear mixed-effects models were developed to evaluate the relationship between back-calculated lengths and environmental variables, including discharge and cumulative growing degree days (GDD). Fish condition was also assessed by developing annual length-weight regressions and modelling fish weights under varying river discharge and GDD values on the James River. Overall increases in annual growth increment and length-weight regression slopes were observed for Channel Catfish in the James River as river discharge increased. However, growth of Channel Catfish in the Big Sioux River was negatively related to GDD. James River Flathead Catfish condition remained similar across the study years, but growth increments increased with discharge. By modeling potential future environmental conditions under varying climate scenarios, it may be possible to identify how these populations will be impacted by changing climatic conditions and how that may impact their management.

AUTHORS: Cali Engel, University of Nebraska-Lincoln; Mark Pegg, University of Nebraska-Lincoln

ABSTRACT: Aquatic invasive species (AIS) have been a growing concern for many fisheries managers and biologists throughout the United States. In Eastern Nebraska, White perch (Morone americana) have been found in a variety of lakes, including Branched Oak Lake, Pawnee Lake, Holmes Lake, and Wildwood Lake. Waterbodies with high densities of this species may cause them to become stunted, maintaining a small size and being undesirable by anglers. Branched Oak Lake and Pawnee Lake contain an abundance of stunted white perch, making management of these reservoirs difficult. Interestingly, there are at least two reservoirs in Southeast Nebraska that contain populations of white perch that are not stunted. Despite their geographic proximity to Branched Oak Lake and Pawnee Lake, Holmes Lake and Wildwood Lake contain populations of white perch desirable to anglers. This study assesses the age structure and growth rates of White perch populations in these four lakes to better understand the differences in population dynamics of populations across different densities. Size structures were markedly different among the four study lakes as expected. Exact differences between stunted and non-stunted populations will be compared to begin determining factors that may influence the propensity for stunting.

AUTHORS: Ethan T. Scott, Eastern Illinois University; Daniel R. Roth, Eastern Illinois University; Eden L. Effert-Fanta, Eastern Illinois University; and Robert E. Colombo, Eastern Illinois University

ABSTRACT: This study investigates the population dynamics of Smallmouth Bass (Micropterus dolomieu) in the Kaskaskia and Vermilion Rivers in Illinois, comparing supplementally stocked populations with naturally reproduced ones. Stocking efforts in the Kaskaskia River have aimed to support recreational fisheries for over a decade. Yet, the contribution of stocked fish to long-term population sustainability has not been fully assessed. In contrast, the Vermilion River supports natural recruitment, and recent dam removals have improved fish diversity and habitat quality, potentially benefiting the abundance of sportfish like Smallmouth Bass. Our primary objectives are to evaluate the relative abundance and demographics of Smallmouth Bass populations in both rivers and assess dynamic rate functions such as age, growth, and mortality. To achieve these objectives, we conducted surveys at 12 sites in each river using pulsed-DC boat electrofishing during the spring and fall. All fish were measured, weighed, and tagged with passive integrated transponder (PIT) tags. Pectoral fin rays were collected as a non-lethal aging structure, and microchemistry analysis will be used to identify recruitment sources by examining elemental ratios. Initial results from the Kaskaskia River suggest that this population is primarily supported by stocking, with Smallmouth Bass most abundant in areas where stocking occurs, particularly near the Shelbyville Dam. This study will provide critical insights into the effectiveness of supplemental stocking in enhancing Smallmouth Bass populations while identifying the natural factors that contribute to successful recruitment in free-flowing systems like the Vermilion River. By comparing two rivers with distinct recruitment mechanisms and environmental stressors, this research will inform more effective management strategies tailored to each system. The findings will also offer broader applications for managing Smallmouth Bass fisheries across similar Midwestern River systems.

AUTHORS: Kristen Patterson: Minnesota Department of Natural Resources; Loren Miller, Minnesota Department of Natural Resources; Beth Holbrook, Minnesota Department of Natural Resources; Chris Smith, Minnesota Department of Natural Resources: Derek Bahr, Minnesota Department of Natural Resources

ABSTRACT: Burbot (Lota lota) are a unique fish in Minnesota as the only freshwater member of the cod family Gadidae and the only under ice spawner. There has been a variable history of appreciation across the state from a productive commercial fishery to some generalized opinion as “trash fish”. Although relatively little is known about populations in Minnesota, Burbot was recently designated a game fish and will have a bag limit set in 2025. Minnesota DNR staff have noted increased Burbot angling interest and have expressed concerns about current exploitation and future potential impacts on area lakes if angling pressure continues to build. Burbot are not well represented with methods employed in current fisheries assessments, and generally targeted with methods outside of standard protocols, e.g. hoop or trammel netting, set or long lining. Without employing intensive sampling efforts, we aim to use single nucleotide polymorphisms (SNPs) to determine whether Burbot are currently showing signs of genetic depression in popular fisheries and if this could be a useful method to gain population level information moving forward. We will share our current knowledge on Burbot populations in Minnesota, preliminary genetic analysis results, and welcome input and discussion for future study and management of this cold-water fish.

AUTHORS: Stephen M. Tyszko, Ohio Department of Natural Resources, Division of Wildlife; Jeremy J. Pritt, Ohio Department of Natural Resources, Division of Wildlife; Richard D. Zweifel, Ohio Department of Natural Resources, Division of Wildlife; Stuart A. Ludsin, The Ohio State University; Joseph D. Conroy, Ohio Department of Natural Resources, Division of Wildlife; Jay Kelly, The Ohio State University; Michael Figueroa, Ohio Department of Natural Resources, Division of Wildlife.

ABSTRACT: Stocking yearling Channel Catfish to mitigate perceived predation by Largemouth Bass has long been the convention despite greater costs compared to stocking smaller life stages. We quantified recruitment of stocked cohorts of Channel Catfish and investigated the effects of stocking life stage (fingerling vs. yearling), Largemouth Bass density (low vs. high), and their interaction on the percentage of a cohort recruiting to the adult population and fishery. Marked (magnetized wire tags) cohorts of advanced fingerling and yearling Channel Catfish were concurrently stocked into reservoirs with low (7 reservoirs, CPUE < 100 fish/h) and high-Largemouth Bass density (5 reservoirs, CPUE > 100 fish/h) populations. We sampled these reservoir Channel Catfish populations with baited, tandem hoop nets 7–8 years after stocking and estimated recruitment. We used a linear mixed model with reservoir as a random effect to test whether cohort recruitment differed by life stage stocked, Largemouth Bass density, or their interaction. Overall, the mean percentage of Channel Catfish recruiting to the adult population and fishery in cohorts stocked as advanced fingerlings was 2.4% (SE = 0.69%) and the mean percentage in cohorts stocked as yearlings was 10.6% (SE = 2.8%). Largemouth Bass density did not have a significant effect on recruitment (P = 0.43) while the effects of stocking life stage (P < 0.001) and the interaction between Largemouth Bass density and stocking life stage (P < 0.003) were significant. The highest recruitment occurred in cohorts stocked as yearlings in reservoirs with high densities of Largemouth Bass. Stocking advanced fingerling Channel Catfish can produce viable year classes in reservoirs with low or high densities of Largemouth Bass. In addition to higher cost, stocking yearling Channel Catfish may result in excessive densities and slow growth.

AUTHORS: Danielle Shubat, Eastern Illinois University; Daniel Roth, Eastern Illinois University; Robert Colombo, Eastern Illinois University; Eden Effert-Fanta, Eastern Illinois University

ABSTRACT: Channel Catfish (Ictalurus punctatus) are a popular and sought after sportfish to anglers across the United States, having substantial value for both recreational and commercial fisheries. However, their populations in impoundments often rely on stockings of fingerlings. In Illinois, the lack of standardized sampling protocols for catfish has made it difficult to adequately evaluate stocking efforts and assess population dynamics. This study aimed to determine the most effective sampling methods for Channel Catfish in impoundments, assess demographic variation among impoundments, and test the efficacy of artificial spawning structures to increase natural reproduction and recruitment in three Illinois reservoirs (Lake Charleston, Lake Mattoon, and Lake Paradise). After two years of seasonal sampling using multiple gears, we found that baited tandem hoop-nets in the fall yielded the best catch rates and we will continue to use this sampling method. Our population assessments and microchemistry analyses of pectoral spines show that Channel Catfish in these lakes are primarily stocked fish, suggesting low natural reproduction. However, the relationship between stocking rates and the observed differences in population density and demographics remains unclear. We hypothesized that the lack of recruitment may be due to insufficient spawning habitat and sought to increase availability of this habitat by adding nest boxes in the study lakes. Preliminary trials showed that Channel Catfish used these structures, and future goals include expanding nest box installations and monitoring for natural recruitment over time. Adding nest boxes to create suitable habitat for these catfish to reproduce may facilitate annual recruitment thereby reducing cost and effort of hatchery operations. If successful, this approach could be implemented in other lakes and ponds to naturally sustain catfish populations.

AUTHORS: Ryan Eastman, Wisconsin Cooperative Fishery Research Unit; Jason Breeggemann, Wisconsin Department of Natural Resources; Robert Davis, University of Wisconsin - Madison Center for Limnology; Daniel Dembkowski, Wisconsin Cooperative Fishery Research Unit; Daniel Isermann, U.S. Geological Survey

ABSTRACT: Green Bay and its tributaries support a world-class fishery for trophy muskellunge that attracts anglers from across North America, but there has been little evidence of natural recruitment and the population remains reliant on stocking to sustain the fishery. Previous efforts to document natural recruitment have focused on the Fox and Menominee rivers where spawning is known to occur. Results of these assessments suggest that hatching success in these rivers is limited. However, recent telemetry-based research indicates that approximately half of Green Bay muskellunge spawn in non-tributary locations. These locations could represent important yet unconsidered sources of natural recruitment in southern Green Bay. Furthermore, anecdotal observations suggest spawning occurs in the Sturgeon Bay area but it is unknown if these fish contribute to the broader southern Green Bay population. Our objectives for this project are to determine if: (1) successful hatching is occurring at open-water locations in Green Bay, including locations in the Sturgeon Bay area, (2) presence of eggs or larval muskellunge at a location is related to a suite of habitat characteristics including distance to shore, bottom slope, depth, dissolved oxygen, substrate type, and aquatic vegetation, and (3) muskellunge spawning in the Sturgeon Bay area contribute to the overall population in southern Green Bay. We are integrating intensive egg and larval fish sampling and acoustic telemetry to address our objectives. We will present preliminary results related to spawning and hatching in non-tributary locations based on sampling efforts during the 2024 field season. We will also discuss the framework of our acoustic telemetry approach to assess the contribution of muskellunge spawning in the Sturgeon Bay area to the broader Green Bay population.

AUTHORS: Kaden Ball, South Dakota State University; Chuck Mordhorst, Arizona Game and Fish Department

ABSTRACT: This study examined the population dynamics of a severely stunted Yellow Perch Perca flavescens population in a high mountain reservoir in the White Mountains of Arizona. River Reservoir sustains a low-density population of trophy Brown Trout Salmo trutta creating a highly prized regional fishery. Yellow Perch have been determined to be an important prey item for Brown Trout in this system contributing to the large sizes Brown Trout attain in the reservoir. The yellow perch population has always been assumed to be stunted based on field observations, but this had never been confirmed. In order to determine if stunting was occurring and to what extent we aged Yellow Perch using otoliths and quantified rates of growth recruitment and mortality. We determined that Yellow Perch in this system are severely stunted relative to other populations and discuss the implications for managing a highly utilized trophy Brown Trout fishery based on these results.

AUTHORS: David D. Duvernell, Missouri S&T; Veronica M. Lee, Missouri S&T; Eric J. Ludwig, Missouri S&T; Aaron D. Geheber, University of Central Missouri; Brett Landwer, Missouri Department of Conservation; Leah K. Berkman, Missouri Department of Conservation

ABSTRACT: Biodiversity monitoring in freshwater habitats provides essential data for assessing and quantifying spatiotemporal patterns and long-term changes. Fisheries biologists use a variety of capture-based methods for biodiversity sampling. Non-capture-based methods have come into common use that rely on the detection of environmental DNA (eDNA), which is released by organisms into their environment. Metabarcoding involves the filtering and extraction of eDNA from samples, followed by sequencing and alignment to a reference database to infer species presence. We worked closely with the Missouri Department of Conservation (MDC) to perform comparative biodiversity assessments using traditional capture-based methods along side eDNA metabarcoding methods. In support of our efforts, we submitted 189 new reference sequences to GenBank, to bring statewide databased coverage of Missouri fish species to over 90%. We teamed with the Resource Assessment and Monitoring (RAM) program to sample sites in six drainages of the Missouri Ozarks, and we worked with Cape Girardeau fisheries biologists to sample lowland habitats in Black Island Conservation Area along the Mississippi River. In Ozark streams we were able to detect approximately double the number of species compared to standard RAM sampling methods, while in the aquatic habitats at Black Island we increased the number of documented species by more than a third relative to MDC survey records dating back to 1940. eDNA sampling missed or failed to discriminate among very few species detected by RAM sampling or documented at Black Island. These missed species were either rare (often single specimens) or were pairs or trios of closely related species with highly similar sequences that were indiscernible using eDNA sequencing methods. Spatial analyses demonstrated that eDNA sampling was sensitive to changes in fish assemblages along Ozark stream habitat gradients, and habitat complexity at Black Island.

AUTHORS: Lewis J. Bruce, Iowa Department of Natural Resources; John Lorenzen, Iowa Department of Natural Resources

ABSTRACT: Creel surveys (i.e., counting and interviewing anglers) are one of the sampling tools used to gauge the amount and type of fishing activity on a pond, lake, or river. Creel surveys provide important information about user demographics, preferences towards fish species and sizes of fish, fish harvest, trip length, and trip expenditures. Collecting these data gives managers insight into what their constituents want. A traditional creel survey consists of two components: 1) random counts of anglers to assess the level of use; and 2) angler interviews to determine more about the typical fishing trip (e.g., how long, what they are catching) and other information about the angler. Randomly counting anglers requires a creel clerk to be on site regularly and, therefore, limits the number of concurrent creel surveys that can be conducted using this traditional method. Another issue with traditional creel surveys is the fact that the mere presence of what some of the public perceive to be a law enforcement figure can result in anglers altering their behavior (e.g., leaving the lake). Time lapsed photography (TLP) was used to collect diurnal count data from multiple lakes simultaneously and these data were collected in an unbiased manner. Cameras were used seasonally (i.e., open water and ice fishing) at some locations and year-round at others. During a 4 year period 20 urban ponds were surveyed using TLP. Hide box maintenance, camera reliability, vandalism, and data processing efforts were also monitored and quantified during this project.

AUTHORS: Keith Hurley, Nebraska Game and Parks Commission

ABSTRACT: FinCatchDE is a mobile-friendly, data entry application that was developed as part of the FinCatch ecosystem - Nebraska Game and Parks Commission’s new database and analysis system for lentic fish sampling data. Utilizing a University of Nebraska – Lincoln capstone computer science project provided a low-cost alternative in obtaining a team of developers to generate this component. Additionally, along the way both technological and data-driven innovations were implemented to improve fish community sampling in the state. We will discuss the process and ideas used for FinCatchDE during this presentation in the hopes that others who are upgrading and transitioning their sampling databases can benefit from our lessons learned.