2025 Midwest Fish & Wildlife Conference

AUTHORS: Braden Lensing, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin-Stevens Point; Daniel Dembkowski, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin-Stevens Point; Joshua Raabe, University of Wisconsin-Stevens Point; Jason Breegemann, Wisconsin Department of Natural Resources; Daniel Isermann, U.S. Geological Survey, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin-Stevens Point

ABSTRACT: Previous research indicates that lake sturgeon Acipenser fluvescens recruitment is limited in the Lower Fox River below De Pere Dam. Habitat enhancements in the form of an offshore reef have been proposed to potentially improve the recruitment of lake sturgeon. However, identifying spawning habitats for other species could help to ensure that restoration efforts for lake sturgeon do not result in loss of spawning habitat for other species. The Lower Fox River supports spawning runs of walleye Sander vitreus and lake whitefish Coregonus clupeaformis, both of which support important fisheries in southern Green Bay. Our objectives are to 1) describe spatial variation in walleye and lake whitefish egg densities in the LFR below De Pere Dam to inform placement of the lake sturgeon spawning reef; 2) determine if spatial variation in egg densities are related to a suite of environmental variables (e.g., flow, depth, and substrate), 3) determine if spatial distributions of eggs are similar for walleye and lake whitefish, and 4) describe the timing (e.g., start, peak, end, and duration) of walleye and lake whitefish spawning. Heat maps generated from relative egg densities illustrate the spatial distribution of walleye and lake whitefish egg densities and reveal significant overlap in egg deposition between the two species, as well as notable overlap with three of four proposed reef locations. The 2023 lake whitefish spawning period spanned 14 days, beginning on November 8 and concluding around November 21. In contrast, the 2024 walleye spawning season lasted 38 days, commencing on March 18 and ending about April 25.

AUTHORS: Kayla Lenz, 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; Carl Klimah, Mille Lacs Band of Ojibwe

ABSTRACT: Mille Lacs Lake located in the 1837 Ceded Territory in central Minnesota offers a unique site for assessing the movement of fish throughout a large temperate lake. The relative shallowness of the lake and resultant lack of a thermocline allows ogaawag (walleye Sander vitreus) to forage throughout the lake, thus maximizing their range. Ogaawag , have been impacted by the many changes happening in this system over the past several decades, resulting in a variable but overall decreasing population between 1980 and 2016, when the population seems to have plateaued. This decrease has largely been attributed to a decrease in annual recruitment from hatching to age-2, but the root cause of that recruitment problem is yet unclear. In other large lake systems, ogaawag frequently display spawning site fidelity, making them especially reliant on a relatively small spawning area. Disturbances and changes in these areas may decrease overall reproduction and decrease fry survival. Identifying and protecting these critical sites may maintain annual recruitment of Mille Lacs ogaawag. The purpose of this study was to identify ogaawag spawning sites across years, characterize habitat type, and quantify spawning site fidelity of adult ogaawag in Mille Lacs Lake. Here we examine the movements of 70 tagged adult ogaawag during the spawning periods of 2019, 2020, and 2021 to determine the proportion of ogaawag that display spawning site fidelity and which areas of the lake were “hotspots” for spawning. Using an acoustic telemetry array, we examine the relationships between sex, length, detection depth, average residence time at each receiver, and spawning site fidelity to establish patterns of behavior among ogaawag. We found that ogaawag in Mille Lacs display spawning site fidelity at high rates (96%) and identified areas with rocky and/or hard substrate, lots of wind/wave action, and that are near undeveloped shoreline to be hotspots of ogaawag activity during the spawning season. We also observed what is likely an occurrence of skipped spawning in a female ogaa. Findings from this study should be used to create new stewardship plans to protect in-lake, shoreline, and upland habitats near spawning aggregation sites in Mille Lacs Lake. These approaches may be applicable to other large lake ecosystems.

AUTHORS: Jeston Hassler, South Dakota State University; Maxwel Wilkinson, University of Wisconsin-Stevens Point; Quinnlan Smith, University of Wisconsin-Madison Center for Limnology; Joseph Mrnak, Wisconsin Department of Natural Resources-Escanaba Lake Research Station/University of Wisconsin-Madison Center for Limnology

ABSTRACT: In recent decades, some lakes in the Ceded Territory of Wisconsin (approximate northern third of the state) have experienced increasing largemouth bass Micropterus salmoides abundance coupled with declining walleye Sander vitreus abundance. These shifts in abundance have become of management concern, as largemouth bass have been hypothesized to negatively influence walleye populations through potential competitive or predatory interactions. Yet, a mechanistic understanding of these ecological interactions remains relatively unknown. As climate change continues to alter thermal habitat in northern Wisconsin lakes, understanding how warming water temperatures may influence largemouth bass and walleye interactions, specifically their consumption rates of prey items, could assist in the future management of the two species. Thus, our objectives in this study were to 1) calculate diet overlap and consumption rates of common prey items for largemouth bass and walleye in a northern Wisconsin lake and 2) simulate consumption rates of largemouth bass and walleye in predicted climate change scenarios. Our study site, Little John Lake located in Vilas Co., Wisconsin, contains a naturally recruiting walleye population and fish assemblage similar to many other northern Wisconsin lakes. We intensively sampled diets of largemouth bass and walleye in Little John Lake from May-October in 2024 and took a bioenergetics approach to estimate and simulate consumption rates of these species under climate-change scenarios. Increased rates of consumption were apparent for both species, notably of yellow perch Perca flavescens and Lepomis spp., yet walleye consumption rates slowed when water temperature began reaching their thermal tolerance. Understanding how largemouth bass and walleye consumption rates may differ under climate-change scenarios may give valuable insight into future interactions between these species in northern Wisconsin lakes.

AUTHORS:  William J. Radigan, University of Nebraska; Dr. Mark Pegg, University of Nebraska; Christopher Longhenry, South Dakota Department of Game, Fish, and Parks, Dr. Cameron Goble, Alberta Environment and Protected Areas; Dr. Kevin Pope, United States Geological Survey—Nebraska Cooperative Fish and Wildlife Research Unit

ABSTRACT:  Walleye Sander vitreus and Sauger Sander canadensis are both socioeconomically important sportfish species in Lewis and Clark Lake, an interjurisdictionally managed mainstem Missouri River reservoir fishery. Adult Walleye (n=136) and adult Sauger (n=82) movement patterns were assessed from March 2021 to September 2024 among four management zones corresponding roughly to quarters of Lewis and Clark Lake using acoustic telemetry. We used a multistate live-dead model approach to assess survival, detection, and movement probabilities. Walleye survival probabilities (mean 85%) varied over time. Detection (mean 81%) and movement (mean 14%) probabilities varied by zone. Sauger detection probabilities varied by zone (mean 58%), and transition probabilities varied by sex, with female Sauger more likely (mean 14%) to transition among zones than male Sauger (mean 6%). Approximately 34-44% of all Walleye and Sauger were site residents, moving less than 10 km from their tagging location over the study duration. Non-site resident male and female Sauger utilized 44-47 km of the reservoir. Female Walleye utilized more of the reservoir (58 km) than male Walleye (45 km). Walleye tagged near Fort Randall Dam utilized more of the reservoir (69-72 km) than Walleye tagged elsewhere (47 km). Exploitation estimates were derived from angler-reported tags and entrainment estimates were based on detections recorded on receivers placed downstream of Gavins Point Dam. Annual exploitation (0-19%) and entrainment (0-5%) are considerable sources of loss for adult Walleye and adult Sauger in Lewis and Clark Lake. Examination of Walleye and Sauger movement patterns and sources of loss enables fisheries managers to focus management on areas identified to be important for spawning and validates the appropriateness of maintaining current harvest regulations.

AUTHORS: Thomas S. Jones, Minnesota Department of Natural Resources
Mark Luehring, Great Lakes Indian Fish and Wildlife Council
Heidi Rantala, Minnesota Department of Natural Resources
John M. Hoenig, Virginia Institute of Marine Sciences
Patrick J. Schmalz, Minnesota Department of Natural Resources

ABSTRACT: Abundance of Walleye in Mille Lacs Lake, Minnesota, has decreased since the 1990s. Two important environmental changes likely contributed to these declines. First, water clarity increased abruptly in the mid-1990s and increased clarity continues through the present day. Second, zebra mussels and spiny waterflea invaded in the late 2000’s, leading to a 90% reduction in zooplankton. Efforts to rebuild the stock through low harvest since 2013 have met with limited success. This study used multiple approaches to compare Walleye productivity changes associated with three time periods (pre-water clarity, post-water clarity, and post-invasive species). First, we estimated annual harvestable surpluses by summing Walleye fishing mortality and the resultant change in population size estimated from statistical catch-at-age models. These data were fit to surplus production models making various assumptions about the shape of the sustainable yield curve. Second, we estimated total annual Walleye production using an instantaneous growth model. All models showed reduced production after each ecological event. Recognition of reduced productivity may have ramifications for future Walleye management in Mille Lacs Lake.

AUTHORS: Maxwel Wilkinson, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin - Stevens Point; Stephanie Shaw, Wisconsin Department of Natural Resources, Escanaba Lake Research Station; Joseph Mrnak, Wisconsin Department of Natural Resources, Escanaba Lake Research Station and University of Wisconsin - Madison, Center for Limnology; Greg Sass, Wisconsin Department of Natural Resources, Escanaba Lake Research Station; Daniel Dembkowski, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin - Stevens Point; Daniel Isermann, U.S. Geological Survey, Wisconsin Cooperative Fishery Research Unit, University of Wisconsin - Stevens Point

ABSTRACT: The Ceded Territory of Wisconsin is a lake-rich region that supports important tribal subsistence and recreational fisheries for multiple species. Recently, declines in walleye Sander vitreus production and recruitment, coupled with increases in centrarchid abundance (e.g., largemouth bass Micropterus salmoides and bluegill Lepomis macrochirus) have created challenges for managers in terms of maintaining desired fish community structure amidst changing environmental conditions and angler preferences. Competitive and predatory interactions between centrarchid species and walleye have been hypothesized to influence walleye natural recruitment, notably in small lakes (

AUTHORS: Joshua Fluur, Southern Illinois University; Gregory Whitledge, Southern Illinois University

ABSTRACT: Walleye (Sander vitreus) is a popular sportfish whose populations are often supported by maintenance or supplemental stocking, with most fish stocked as fry, fingerlings, or advanced fingerlings. Evaluation of stocking efficacy is important to inform decisions regarding fish stocking rates and sizes and allocating hatchery fish to locations where maintenance or supplemental stocking is most needed. Several types of artificial tags or marks can potentially be used to identify stocked fish, but many have various drawbacks. Natural chemical markers in otoliths or eye lenses offer several advantages compared to conventional tags or marks and can be used to identify stocked fish when differences between hatchery-reared and wild fish are present. However, the accuracy of these approaches for identifying Walleye stocked at either fry or fingerling sizes has not been evaluated. Thus, the objectives of this study are to assess identification accuracy for Walleye stocked as fry or fingerlings using otolith microchemistry and eye lens stable isotope analysis. Known stocked fish and fish moved between chemically distinct locations to simulate stocking were obtained from several sources. Results to date indicate that otolith microchemistry can identify Walleye stocked as fingerlings with high accuracy and that the source hatchery signature can be detected in fish stocked as early as three days post-hatch. Results of this study will provide guidance regarding applications of otolith and eye lens chemistry techniques to assess contributions of stocking and natural reproduction to Walleye populations and relative efficacy of stocking fish at varied sizes.

AUTHORS:  Caleb J. Branam, Michigan State University; Holly S. Embke, Midwest Climate Adaptation Science Center, U.S. Geological Survey; Chris L. Cahill, Michigan State University

ABSTRACT:  A key challenge in inland fisheries is assessing numerous lakes across vast landscapes within an agency’s jurisdiction given limited resources. To reconcile this, a variety of data-limited methods have been developed to assess the status of inland fish populations. However, these tools often do not explicitly address the potential for population dynamics, or they make strong assumptions that a given population or stock is at equilibrium. Furthermore, these assessment tools are rarely simulation tested in inland fishery settings to determine their efficacy. Without knowing how these methods perform when confronted with simulated dynamics where truth is known, the effectiveness of such tools remains uncertain. Our objective was to evaluate how commonly used assessment methods for Walleye Sander vitreus performed when tested against simulated data. To achieve this, we developed an age-structured simulation model for Walleye and then evaluated the performance of the following commonly used assessment methods: mark-recapture, catch per unit effort as an index of relative abundance, size-structure indices as an index for population status, and production-based dynamics as an index of population status. This presentation will lay out the research plan for our study, present initial results for at least one assessment method, and touch briefly on the implications of potential results.

AUTHORS:  Devon C. Oliver, MNDNR; Loren Miller, MNDNR; Anthony Sindt, MNDNR; Cristian Hernandez, University of Minnesota

ABSTRACT:  Redhorse species face a diverse array of impacts and conservation issues but often remain overlooked relative to their sportfish counterparts. Furthermore, they often lack constituency groups that advocate for their conservation. River Redhorse is a member of the Catostomidae family that have experienced reductions in abundance and range over the last century and are listed as critically imperiled in Kansas, New York, Louisiana, and Florida, imperiled in Wisconsin, Michigan, Virginia, and North Carolina, and vulnerable in Illinois, Indiana, West Virginia, Mississippi, and Georgia; additionally, they are listed as a species of special concern in Canada. Furthermore, like many potentially imperiled or vulnerable catostomid species, River Redhorse suffers from a paucity of demographic and life history information. Additionally, for River Redhorse, there is some ambiguity as to which morphological characteristics should be used to positively identify them relative to Shorthead and Greater Redhorse, which must be addressed first. Morphometrics and meristics used to determine species id can be highly variable, require harvest of the specimen, subjective, or are inconsistent in their determination across metrics both within and across different source material. To address this knowledge gap and to provide clarity in species identification for biologists and conservation hobbyists this study, 1) evaluated and compared morphometrics and meristics used to positively identify River Redhorse relative to Shorthead and Greater Redhorse, 2) determined useful morphometrics and meristics for identification of the three redhorse species within Minnesota based on genetically confirmed specimens.

AUTHORS:  Drew Holloway, Muncie Bureau of Water Quality

ABSTRACT:  Technology and standardization in electrofishing has come a long way over the years. For this presentation I will be using two of these technologies to help guide future sampling efforts for the Bureau of Water Quality in Muncie, IN. In 2022, we purchased the Smith-Root Apex electrofishing box to replace our outdated and heavily bandaged GPP Electofisher. Now, our historical monitoring stations could be GPS tracked and digitally recorded allowing us to see how yearly variation could affect our electrofishing results. Having previously recorded Side Scan Sonar (SSS) for these same historical sites it gave us the opportunity to not only see if habitats sampled are representative to the species found at each site but if a change in path also changed our fish community diversity. Three years of single pass electrofishing data will be presented from 10 randomly selected West Fork White River sites. The associated habitats will be represented based on SSS categories from previous works done by the Bureau of Water Quality.

AUTHORS:  Kristen Bouska, U.S. Geological Survey, Upper Midwest Environmental Sciences Center; Levi Solomon, Illinois Natural History Survey, Illinois River Biological Station; Andy Bartels, Wisconsin Department of Natural Resources; Jim Lamer, Illinois Natural History Survey, Illinois River Biological Station; Hae Kim, Missouri State University; Quinton Phelps, Missouri State University

ABSTRACT:  Vital rates (i.e., recruitment, growth, and mortality) are the processes responsible for changes in abundance and biomass of a population through time. Knowledge of vital rates and the factors that contribute to interannual variability in vital rates can provide critical information in determining why fish population abundances increase or decrease across time and space. Between 2018 and 2020, over 2,500 individual Bluegill were collected from five study reaches on the Upper Mississippi River and one study reach on the Illinois River. Together these study reaches span nearly 1500 river kilometers and 7 degrees of latitude and represent gradients such as temperature, discharge, and clarity. From the collected individuals, otoliths were extracted, and ages were estimated. Hierarchical growth models were used to estimate growth model parameters and mean-length-at-age for each species and study reach. Logistic regression was used to estimate average age and length at maturity. Study reach-specific age-length keys were created to assign ages to unaged fish collected during standardized sampling and used to estimate indices of recruitment, stock and annual mortality. We first investigated patterns in growth, maturity, recruitment, and mortality across study reaches. Next, we sought to understand the relative contribution of stock density, habitat availability, temperature gradients, and disturbance dynamics on population dynamics. With this presentation, we aim to improve our understanding of how and why bluegill populations vary across these two large rivers and plan to extend our analyses to several other species of interest.

AUTHORS:  Michael Louison, Mckendree University

ABSTRACT:  Microplastics have emerged as a major contaminant of concern in a host of ecosystems, including freshwater systems. Previous work has documented the abundance of microplastics in the bodies of various organisms, finding that aspects of an animal’s niche (feeding habits, habitat choice, etc.) may influence exposure to microplastic contamination. To further our understanding of microplastic abundance in freshwater systems, we conducted a survey of freshwater fish taken from the lower Kaskaskia River in Southern Illinois, USA. The first sampling site (done via direct current boat electrofishing) was stationed directly below the Carlyle Lake dam (a heavily used recreational site with abundant pollution from litter) with two additional downstream sites also sampled. Five species of fish (flathead catfish Pylodictis olivaris, freshwater drum Aplodinotus grunniens, smallmouth buffalo Ictiobus bubalus, white crappie Pomoxis annularis, and gizzard shad Dorosoma cepedianum) of differing feeding ecologies were sampled, dissected, and subsequently examined for microplastics both visually (examinations of gills and stomach contents under microscope) and chemically (analysis of nanoplastic concentration in muscle tissue). Results revealed differences in microplastic load between fish species and between sites, as well as differences in measures of contamination using visual and chemical methods. Our results add to the present knowledge of microplastic abundance in organisms, and specifically how feeding type and proximity to sources of human pollution may impact microplastic abundance in freshwater fish.

AUTHORS:  Ella Humphrey, University of Nebraska Lincoln; Jonathan Spurgeon, U.S. Geological Survey & Nebraska Cooperative Fish and Wildlife Research Unit; Sarah Sonsthagen, U.S. Geological Survey & Nebraska Cooperative Fish and Wildlife Research Unit

ABSTRACT:  Climate change may impact the persistence of fish species based on their ability to adapt to changing environmental conditions, such as decreasing flows and rising temperatures. Fish rely on temperature regimes within their thermal tolerance to maintain metabolic processes. Thus, temperatures outside these tolerances will result in fish losing the ability to continue metabolic processes resulting in severe stress or death. Bigmouth shiner Hybopsis dorsalis is widespread throughout Nebraska and previous studies indicate that increasing temperatures may affect their range. Therefore, we evaluated the critical thermal maximum (CTmax) of H dorsalis and analyzed their expression of heat shock protein 70 (HSP-70) to quantify a thermal stress response over a gradient of temperatures (25-31°C). We found that HSP-70 expression was upregulated in response to temperatures >25°C, indicating a stress response. We then compared this thermal threshold to the yearly maximum temperatures from 42 rivers and streams in Nebraska to determine areas where H dorsalis may already be at risk for thermal stress within their range. About 88% of the sites surpassed 25°C at some point between May and September. This study provides evidence that H dorsalis may be experiencing thermal stress across Nebraska, which future climate scenarios may worsen.

AUTHORS:  Ryan Skowronski, Eastern Illinois University; Eden Effert-Fanta, Eastern Illinois University; Dan Roth, Eastern Illinois University; Trent Thomas, Illinois Department of Natural Resources; Robert Colombo, Eastern Illinois University

ABSTRACT:  The Midwestern landscape has been converted from forests and prairies into land used for urban development and agricultural practices over the past two centuries. This transformation in landscape composition has disrupted ecosystem function and reduced the stability of stream habitats by accelerating bank erosion, decreasing riparian buffers, and lowering water quality. These changes have led to the degradation of stream habitat heterogeneity, which is a key factor influencing the biotic integrity of fish assemblages. Habitat restoration is a common mitigation strategy for reversing stream degradation, though empirical research evaluating the effectiveness of habitat restoration is insufficient in the Midwestern United States. This study aims to investigate the temporal shifts in fish biotic integrity in four Illinois streams restored in the past 15 years using historical fish community data. We expect habitat enhancement to initially disrupt fish assemblages but show an overall increase in biotic integrity in restored sites over time with a rise in habitat specialist and intolerant fishes. Evaluating the outcomes of these restoration projects is critical to conserve fish communities in degraded streams and improve future restoration methods.

AUTHORS:  Hannah Lenning, Iowa Department of Natural Resources/University of Nebraska at Kearney; Melissa Wuellner, University of Nebraska at Kearney; Seth Fopma, Iowa Department of Natural Resources; Keith Koupal, Nebraska Game and Parks Commission; Jayne Jonas-Bratten, University of Nebraska at Kearney

ABSTRACT:  This research evaluates the impacts of restoring backwaters, a habitat type in large floodplain rivers that are essential for maintaining their high diversity of fauna. The restoration of backwaters has been an integral part of managing fish populations on the Upper Mississippi River since 1990 and is a major component of the Upper Mississippi River Restoration Program. This research looks at a 2013 restoration project that expanded on the traditional approach by restoring multiple backwaters in a single effort, resulting in 63 acres of backwater channels dredged within four backwaters, proximal in space (within 14-km reach) and time (2013-2017). Here, we evaluated whether benefits of restoration (increased catch or shifts in size structure) are observed beyond project boundaries and identified species that are indicators of backwater restoration, comparing two river reaches using a BACI approach. The river reach containing restored backwaters (Pool 12) is the Impact area, and a downstream river reach without restored backwaters (Pool 13) is the Control area. Historical, day electrofishing data was utilized, with the before period including sampling years prior to any construction (2006 – 2012) and the after period including years after construction concluded (2018 – 2024). For representative species, relative abundance was compared using the Kruskal-Wallis test. Nonmetric multidimensional scaling (NMDS) was conducted to visualize the similarities and differences between fish assemblages of each BACI group. Finally, indicator species analysis was conducted on each BACI group, which identified indicators of river reaches with and without this approach to backwater restoration. Understanding the scalar impact of Pool 12 restoration and its impact on fish assemblages informs the future planning of restoration projects to maximize program resources and efficiency.

AUTHORS:  Tyler Hessler, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri; Craig Paukert, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri; Yi Shang, Department of Electrical Engineering and Computer Science, University of Missouri; Zhenduo Zhai, Department of Electrical Engineering and Computer Science, University of Missouri; Shiqi Wang, Department of Electrical Engineering and Computer Science, University of Missouri; Jason Persinger, Missouri Department of Conservation

ABSTRACT:  The use of side-scan sonar has seen a dramatic increase in use in a variety of studies including those with the aim to characterize fish habitat. Side-scan sonar has been used to quantify habitat for well over a decade now and has seen promise in a variety of aquatic systems from coastal reefs to backwater bayous. The use of UAS (also known as aerial drones) has also seen more frequent use in mapping features in aquatic systems. In our study, we propose the use of side-scan sonar and UAS to better standardize and streamline the collection of fish-relevant habitat data in non-wadeable, mid-sized rivers. Traditionally, identifying habitat from side-scan sonar and aerial imagery was a manual process that could take several hours to days to complete a site. The amount of data that can be quickly accumulated in riverine systems can be daunting, but the use of AI and other software may streamline the implementation of these data and provide another option for a manager’s toolbelt that can increase confidence associated with making informed decisions that rely on accurate habitat data. To date, we have conducted 25 side-scan surveys across 8 sites across the state of Missouri totaling over 80 river kilometers. In addition, we have conducted 30 UAS surveys across these 8 sites as well as another site just used for UAS imagery. Developing a standardized protocol using side-scan sonar and UAS with the power of AI modeling could significantly increase the quality of data collected in mid-sized rivers and also decrease the costs associated with collecting habitat data and delineating imagery manually.

AUTHORS:  Tyler Ham, Missouri Department of Conservation; Shane Bush, Missouri Department of Conservation; Nathan Recktenwald, Missouri Department of Conservation; Christopher Brooke, Missouri Department of Conservation

ABSTRACT:  As many reservoirs constructed throughout the USA continue to age, the quality of the fish habitat in these reservoirs has experienced a concomitant decline. Fish and wildlife agencies, nongovernmental organizations, and concerned anglers have all sought to supplement natural fish habitat by installing habitat structures to concentrate fish and improve angler catch rates. In Missouri reservoirs, these structures are primarily composed of submerged cedar, hardwood, or mixed cedar and hardwood trees. Being natural materials, these structures decay over time and require maintenance to provide adequate fish cover. To that end, there exists a paucity of knowledge on the physical longevity of these structures installed in Missouri reservoirs. The objectives of this study were to define the current condition and longevity of fish habitat structures in Missouri reservoirs and to provide management recommendations for the most efficient long-term maintenance and enhancement of habitat structures. Sonar imaging was employed on Table Rock Lake, Bull Shoals Lake, and Harry S. Truman Reservoir in Missouri to generate qualitative categorical condition scores for fish habitat structures. In each reservoir a spectrum of structure types was assessed that represented multiple year classes spanning over a decade. Condition scores were used to further categorize structures based on maintenance needs. We also examined the influence of depth, location, and material on structure longevity. This project focused on evaluating the controllable factors that can improve effectiveness and efficiency of fish habitat projects. Identifying the impact of these factors on fish habitat enhancement projects will have direct application to future decision making and benefit anglers using Missouri reservoirs.

AUTHORS: Brittany L. Harried, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO; Jacob T. Westhoff, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO

ABSTRACT: The Bluestripe Darter (Percina cymatotaenia) is endemic to Missouri, is a species of conservation concern, and has been petitioned for listing under the Endangered Species Act. We conducted a study to evaluate the species’ threats, genetic diversity, and population trends. Objectives for this study were to: 1) duplicate Bluestripe Darter sampling effort from past sites and observe trends in population status, and 2) assess the range-wide geographic patterns of genetic variation within Bluestripe Darter. Sampling efforts from 2000-2002 were duplicated during June-August 2024 for 46 sites across five rivers in southern Missouri using seining methods that targeted small-bodied benthic fishes. Furthermore, limited environmental covariate and habitat data were collected and additional sampling in a spatially replicated occupancy framework was completed to estimate occupancy and detection at each site. Up to 20 fin clips and vouchers were collected per river to estimate effective population sizes, geographic structure of genetic variation within and between drainages, and contemporary short-term migration rates. Photos of each voucher specimen were also taken to assess external ecomorphology. We detected Bluestripe Darter at 9 out of 46 sites in 2024, which was well below the 23 out of 46 sites where it was detected by surveys from 2000-2002. Results from this study will inform the Species Status Assessment and listing decision for Bluestripe Darter, and will also benefit Heritage reviews, Wildlife Collector Permit reviews, conservation planning, and priority for on-the ground management projects related to identified population threats.

AUTHORS: Brittany L. Harried, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO; Wesley Fitzsimmons, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO; Kaelyn J. Fogelman, Biological and Environmental Sciences Department, Troy University, Troy, AL; Craig P. Paukert, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO; Jane S. Rogosch, U.S. Geological Survey, Texas Cooperative Fish and Wildlife Research Unit, Department of Natural Resources Management, Texas Tech University, Lubbock, TX; Jim A. Stoeckel, School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL; Jacob T. Westhoff, U.S. Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit, School of Natural Resources, University of Missouri, Columbia, MO


ABSTRACT: Aquatic organisms are experiencing impacts from anthropogenic influences (e.g. climate change), resulting in the loss of suitable habitat for many species. Consequently, it is imperative to improve our understanding of the thermal ecology of these organisms to predict how individual species may respond to changes in water temperature and habitat availability. This is particularly important for species of conservation concern and species on the periphery of their range which could experience greater impacts from climate change-related stressors. In this study, we examined the thermal ecology of hatchery-reared Topeka Shiners, and wild Blacknose Shiners, Ozark Shiners and Carmine Shiners from Missouri. Some of these species have restricted distributions or small populations while others have broader latitudinal ranges. We performed laboratory studies to assess multiple thermal metrics including 1) thermal preference, 2) acclimated chronic exposure, 3) respiratory enzyme thermal performance, and 4) critical thermal maximum. The laboratory study results were integrated with distribution models for these species, stream temperature models for Missouri, barriers to movement and migration, and watersheds where conservation is focused to estimate the adaptive capacity of these species and identify stream reaches that may serve as refugia or managed translocations in the face of climate change. Estimating multiple thermal metrics allows us to test for relationships among metrics within and across species and provides a more thorough understanding of the thermal ecology of these species to inform management decisions. Additionally, this provides insight into the most ecologically relevant thermal metrics for informing future, large-scale modelling efforts with other species.

AUTHORS: Jenna Ruoss, School of Natural Resources - University of Nebraska-Lincoln; Christopher Pullano, School of Natural Resources - University of Nebraska-Lincoln; Mark Pegg, School of Natural Resources - University of Nebraska-Lincoln; Jonathan Spurgeon, U.S. Geological Survey, Nebraska Cooperative Fish and Wildlife Research Unit; Kirk Steffensen, Nebraska Game and Parks Commission

ABSTRACT: Pallid Sturgeon Scaphirhynchus albus is a long-lived species that occupy the lower Mississippi River and the mainstem Missouri River, along with its major tributaries. In 1990, Pallid Sturgeon was listed as federally endangered, stemming from anthropogenic activities including habitat alterations and overharvesting leading to population declines. Conservation efforts and studies have primarily focused on understanding life-history requirements, population dynamics, habitat use, and productivity in the mainstem Mississippi and Missouri rivers. Limited information exists on the potential role of tributaries for Pallid Sturgeon recovery. Previous studies documented that Pallid Sturgeon occupy the lower Platte River, a large tributary to the Missouri River, year-round. Nevertheless, the environmental cues that trigger movement into and out of the Platte River are not fully understood. Therefore, our objective was to assess potential environmental cues for immigration and emigration between the Platte and Missouri rivers using acoustic telemetry. We implanted 29 acoustic transmitters and recorded an additional 64 unique Pallid Sturgeon, previously tagged by other agencies in the mainstem Missouri River, throughout 2022-2023 in the Platte River. Pallid Sturgeon were assigned to one of three migratory statuses (e.g., immigration, emigration, or individual occurrence). We used generalized linear models to investigate the additive effects of mean discharge, mean temperature, and photoperiod for Pallid Sturgeon immigration and emigration at the Platte River confluence with the Missouri River. We determined that the global model with the additive effects of mean discharge, mean temperature, and photoperiod was the highest-ranking model for predicting the probability of immigration. In contrast, mean temperature was identified as the best candidate model for predicting the probability of emigration. Our findings provide important insights concerning Pallid Sturgeon migration between river systems. The high affinity that Pallid Sturgeon displayed for the Platte River could suggest that the tributary plays an important role in fulfilling their life-history.

AUTHORS: Maxwell D. Majinska, Quantitative Fisheries Center, Michigan State University; Christopher L. Cahill, Quantitative Fisheries Center, Michigan State University; Christopher S. Vandergoot, Great Lake Acoustic Telemetry Obersvation System

ABSTRACT: Lake Sturgeon Acipenser fulvescens reintroduction efforts are underway throughout the Great Lakes, often through the stocking juvenile fish. However, little is known about juvenile life-history and system-specific behaviors due to historical population declines prior to detailed scientific study, complicating effective management. Due to late maturation (15-25 years) and natal homing behavior of adults, understanding movement patterns of juveniles may provide useful data for evaluating reintroduction goals.

In 2017, the Saginaw River Basin was selected by the Lake Huron Lake Sturgeon Working Group for reintroduction after being functionally extirpated. Age-0 sturgeon are stocked in four rivers: the Cass, Flint, Shiawassee, and Tittabawassee. Natal streamside rearing is not currently proposed for this system; therefore, fish are sourced from the Black River Streamside Rearing Facility (BRSF, Onaway, MI) and the Genoa National Fish Hatchery (GNFH, Genoa, WI). Paired stocking provides a unique opportunity to compare the behavior of fish reared in different settings – non-natal streamside versus traditional groundwater – while using fish from the same genetic unit.

Our study evaluated movement patterns of stocked juvenile sturgeon released in 2022 and 2023 using passive acoustic telemetry. Fish (n = 80) from each hatchery were surgically implanted with InnovaSea V7 or V7D transmitters and stocked proportionally by tag type and hatchery origin among the four tributaries annually. Movement patterns were assessed by measuring total distance traveled, time to first detection, river residence time, and last known location. Preliminary results suggest BRSF fish begin moving downstream later; however, both hatcheries exhibit similar residence time and total travel distance.

AUTHORS:  Benjamin J. Schall, South Dakota Department of Game, Fish and Parks; Lindsey A. P. LaBrie, USGS Cooperative Fish and Wildlife Unit, University of Arkansas; Tanner L. Carlson, Minnesota Department of Natural Resources; Jeff S. Wesner, University of South Dakota; Chelsey A. Pasbrig, South Dakota Department of Game, Fish and Parks; Steven R. Chipps, USGS Cooperative Fish and Wildlife Research Unit, South Dakota State University

ABSTRACT:  Reproductive characteristics for populations of imperiled non-game species are not regularly studied but may be important for identifying factors associated with population sustainability. Understanding reproductive traits in vulnerable species, particularly long-lived species, may provide insight for implementing management actions to respond to changes in angling behavior. This study aimed to assess the reproductive characteristics of a stable population of long-lived Blue Suckers Cycleptus elongatus in the unchannelized Missouri River in South Dakota. We collected demographic information and gonads from 182 Blue Suckers in 2021-2022. We used Bayesian generalized linear mixed-effects models to assess length and weight relationships with gonadosomatic index (GSI) and fecundity and used spawning potential ratios (SPR) to model the influence of varying harvest and minimum length limit (MLL) scenarios. Fish lengths ranged from 560-821 mm. Female GSI increased with length to ~720 mm before declining, and male GSI remained consistent across lengths. Strong positive linear relationships were observed for GSI with fish weight and fecundity. Using recent natural mortality estimates for this population, SPR under current no-limit regulations decreases rapidly as fishing mortality (F) approached 0.10 but implementing a 660-mm MLL would prevent SPR from falling below acceptable limits (0.2-0.3) at F values as high as 0.69. This study demonstrates that reproductive data and SPR modeling can be used to provide length-based regulation recommendations for vulnerable, non-game species that receive less management focus.

AUTHORS:  Shannon J. Fisher, Minnesota Department of Natural Resources

ABSTRACT:  “Rough fish” is a term used to describe multiple native fish species historically perceived by agencies and anglers as having limited value to sport fisheries. Rough fish have been frequently deemed to degrade aquatic habitats, compete with more desired gamefish species, and have low-to-no ecosystem or cultural value. In 2022, the Minnesota legislature directed the Department of Natural Resources (DNR) to develop recommendations for statutory and rule changes to provide necessary conservation measures and research needs for 26 native species designated as rough fish. The DNR convened a stakeholder group of bowfishers, commercial fish harvesters, anglers, and conservation organizations; collected public input on attitudes and management scenarios; and solicited input from Tribes to inform “rough fish” management recommendations. In 2024, the Minnesota legislature elevated the status of “native” rough fish by removing invasive fishes from this new designation and establishing additional protections. As a result of improved native rough fish status, the DNR has launched rulemaking to establish daily and possession limits and restitution values. This presentation will detail the process the DNR undertook with diverse stakeholders and the legislature to inform the passage of the “native rough fish” law and related recommendations for helping ensure more sustainable management of these underappreciated species in Minnesota.

AUTHORS: Steven J. Herrington, The Nature Conservancy, MN-ND-SD;
Tyler Winter, Native Fish For Tomorrow;
Solomon R. David, The University of Minnesota
Matthew L. Miller, The Nature Conservancy, Science Communications

ABSTRACT: North America has the highest diversity of freshwater fishes of any temperate region worldwide. These species face numerous threats to their long-term conservation. Fisheries management is amongst the tools that governments, Tribes, and other interested parties can use to ensure this biodiversity sustainably persists and thrives into the future. “Rough fish” is a pejorative term often used by resource managers and anglers to group a large number of native fishes – including gars and numerous sucker species – that are perceived to have little fisheries or cultural value, and thus are often poorly managed and exploited. In 2024, the State of Minnesota passed the first law in the U.S. affording fisheries management protections for 26 native fishes now recognized by the state as “native rough fish”. This action sets a precedent for recognizing the inherent, cultural, and fisheries importance of these species that can be replicated or adapted by other states nationwide. This presentation will provide an historical perspective of “rough fish” regulations, recommendations for their future conservation management, and applicability to states in the Midwest.

AUTHORS: Samantha A. Embersits, Wisconsin Cooperative Fishery Research Unit; Daniel A. Isermann, U.S. Geological Survey, Wisconsin Cooperative Fishery Research Unit; Daniel J. Dembkowski, Wisconsin Cooperative Fishery Research Unit; Margaret H. Stadig, Wisconsin Department of Natural Resources

ABSTRACT: The Lake Winnebago System (LWS) population in east-central Wisconsin represents one of the largest self-sustaining populations of lake sturgeon Acipenscer fulvescens in North America that supports an annual spearing fishery each February. Lake sturgeon spawn at more than 70 locations within tributaries to the LWS, but the extent and timing of spawning that occurs at many sites remains unknown. Understanding lake sturgeon use of spawning locations is important in allocating sampling effort needed to mark fish and obtain population estimates used in setting safe harvest levels for the fishery. Furthermore, some spawning sites represent habitat improvement efforts implemented by the Wisconsin Department of Natural Resources and little to no evaluation has been performed at these sites to determine relative use and potential for successful hatching. Our objectives were to describe lake sturgeon use, measure egg deposition rates and survival, and verify whether hatching is occurring at selected spawning locations in the Wolf River drainage, including sites where habitat improvements have occurred. Spawning sites were or will be visited repeatedly during the 2024 and 2025 spawning seasons and lake sturgeon are visually counted along defined transects. Eggs are collected with a manual transfer pump and D-frame drift nets are used to collect larvae. We will present results from our first sampling season. The information from our research may help the Wisconsin Department of Natural Resources strategically allocate spring sampling effort so that more sites can be sampled and could provide guidance regarding future habitat improvement projects.

AUTHORS: Juliana Kaloczi, Iowa State University; Michael J Moore, U.S Geological Survey, Iowa Cooperative Fish and Wildlife Research Unit and Iowa State University; Martin Hamel, University of Georgia; Gene Jones, Iowa Department of Natural Resources; Ryan Hupfeld, Iowa Department of Natural Resources, Rebecca Krogman, Iowa Department of Natural Resources.

ABSTRACT: Globally, sturgeon populations have declined due to overharvest for caviar and habitat fragmentation due to dam construction that impairs water quality and disrupts spawning migrations. North American species have had harvest restrictions enacted to recover populations. While similar life history characteristics make Shovelnose Sturgeon vulnerable to many of these same stressors, populations in the Mississippi River basin still support limited commercial and recreational fisheries for roe and meat - conferring the species’ economic, recreational, and cultural importance. Enacting harvest regulations, such as minimum length limits, ensures sustainable harvest and requires knowledge of dynamic rates such as age-specific growth rates. However, the Shovelnose Sturgeon’s long life span and slow growth make estimating these parameters notoriously difficult with traditional methods that rely on annuli counts on bony structures. As a result, there is a lack of reliable growth rates for this species across its range. Therefore, we used an 18-year mark-recapture dataset for Shovelnose Sturgeon collected by the Iowa Department of Natural Resources in the Cedar River at Palisades-Kepler State Park to evaluate incremental growth models for Shovelnose Sturgeon. The Fabens modification of the Von Bertalanffy growth function was used within a Bayesian framework to determine how growth rates vary within the population. Additionally, bomb-radiocarbon age estimates were used to inform a second model within the Bayesian framework to assess how the incorporation of previous knowledge may improve the model. Age estimates and growth rates can be used in population simulations to evaluate sensitivity to harvest under harvest regulations and can inform management across the species’ range.

AUTHORS: Andrew Briggs, Michigan Department of Natural Resources; Justin Chiotti, U.S. Fish and Wildlife Service; James Boase, U.S. Fish and Wildlife Service; Jan-Michael Hessenauer, Michigan Department of Natural Resources; Jeannette Kanefsky, Michigan State University; Brad Utrup, Michigan Department of Natural Resources; Todd Wills, Michigan Department of Natural Resources

ABSTRACT: The Michigan Department of Natural Resources (MDNR) and U.S. Fish and Wildlife Service (USFWS) have been conducting Lake Sturgeon surveys in the St. Clair – Detroit River System (SCDRS) since 1996. Over this period determining sex of Lake Sturgeon has been difficult as the primary method to determine sex has been expulsion of gametes, which rarely occurs (particularly for females). Recent advances in genetic methods have shown that sex of Lake Sturgeon can be determined from a tissue sample or fin clip through molecular sexing. MDNR and USFWS have collected pectoral fin rays from Lake Sturgeon for aging purposes since their surveys began and have stored them over the years, allowing for a portion of these fin samples to be clipped and used for molecular sexing. MDNR and USFWS combined to provide over 2,700 tissue samples to Michigan State University for molecular sexing with 53% of the Lake Sturgeon being classified as female. This presentation will examine if sex ratios differed by location within the SCDRS, how sex ratios change by length, and sex-specific growth rates of Lake Sturgeon.

AUTHORS: Justin Sturtz, South Dakota State University; Benjamin J. Schall, South Dakota Department of Game, Fish and Parks; Matthew J. Ward, South Dakota Department of Game, Fish and Parks; Cody E. Treft, South Dakota Department of Game, Fish and Parks; Christopher Cheek, South Dakota State University

ABSTRACT: Determining the natal origins of fish can provide critical information for fisheries management and conservation efforts. Recirculating Aquaculture Systems (RAS) are advanced, fish-rearing setups that filter and recycle water within the system, significantly reducing the need for fresh water and allowing for high-density rearing of fish under efficient growth conditions. In contrast, traditional fish stocking often involves rearing fish in raceways or outdoor ponds. Differences in forage between RAS (pellet-fed) and pond (natural forage) reared fish may result in unique isotopic signatures in the fish tissue. Historically archived isotope signatures in fish eye lenses may be useful in differentiating rearing sources, providing an additional tool for delineating stock contribution. This study investigates the feasibility of using isotopic composition of fish eye lenses to discern the known rearing environment (RAS vs. pond vs. wild) of fall, advanced fingerling age-0 Walleye (Sander vitreus). We collected 10 RAS-reared, pellet-fed walleye from Cleghorn fish hatchery in Rapid City SD (mean = 159mm), 10 pond-reared natural source-fed walleye from Blue Dog hatchery in Waubay SD (mean = 179mm), and 10 wild- caught walleye from Clear Lake in Sioux Falls SD (mean = 170mm). Eye lens layers were delaminated to remove ~300 µm for each layer, resulting in 3 to 4 layers per fish including the core. Eye lens layers were sent for carbon (δ13C) and nitrogen (δ15N) isotope analysis, and whole eye lenses from the second eye were sent for δ13C, δ15N, and sulfur (δ34S) analysis. Preliminary δ13C and δ15N results illustrated unique signatures among stocking sources, high signature precision for the pellet-fed RAS fish, and shifting signatures with known changes in diet for pond-reared fish. The results of this study could be used by managers who are focusing on identifying the stock contribution of RAS and pond-reared fishes.

AUTHORS: Matt Cochran, HDR Engineering, Inc.

ABSTRACT: The beginning of formal fish culture in North America dates back to the 1800s when some of the first references to hatcheries being used for population mitigation purposes surfaced. While the early efforts were focused on the actual science of fish culture, the need to support culture efforts with facilities specifically designed to aid production soon followed. The design of coolwater, warmwater and coldwater fish production facilities ranges from simple repairs at existing facilities to full scale renovations or brand new state of the art hatcheries that can meet the needs of conservation based fish culture. This talk will outline the history of facilities in North America and highlight design features utilized for sportfish and conservation focused facilities.

AUTHORS: Baylee Thornton, HDR; Matt Cochran, HDR

ABSTRACT: The origin of fish propagation for population recovery dates back to the mid-1800s. Throughout the centuries to follow, fish hatcheries have been designed to focus on mass production. While previous criticisms of such mass production were founded on the basis of environmental harm – including nutrient pollution from fish waste, extirpation of native species by hatchery fish, disease, and the introduction of invasive species – fish hatchery management has entered a new era. Fish hatcheries are now shifting the production focus to enhance conservation and recovery programs of native fishes, in addition to sport fish production. HDR has constructed a tool to help guide management decisions for designing facilities surrounding such programs. Fish hatchery biological programming (“bioprogramming”) is a tool used to analyze biological questions and anticipate the fish rearing environments necessary to answer these questions. The process references fish culture specifications obtained from recognized fish culture manuals, established fish rearing facilities, and fish production managers. The modeling process anticipates fish growth, desired rearing space, and required flow and oxygen demands to produce healthy fish, making it a valuable tool for managing challenges and conflicts in fish hatchery design. It has been used to model and support recovery strategies for several fish species across North America, including Gila trout in Arizona, Pacific salmon species in Washington, coolwater fish in the Midwest, and salmonid species in Canada.

AUTHORS: Steven Gratz, The Ohio State University; Jacob Bentley, The Ohio State University; Stuart Ludsin, The Ohio State University

ABSTRACT: Fatty acids are vital for human health and affect overall well-being while reducing disease risk. Fish tissue contains a plethora of fatty acids including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), two essential omega-3 fatty acids, which are primarily found in fish and help the human body to function properly. Little research has been conducted studying the fatty acid composition of freshwater fishes with a majority of research focusing on saltwater fishes. However, it is important to understand the fatty acid composition among freshwater fishes that support locally sourced food. We sought to understand species, size, and seasonal variation of saturated and unsaturated fatty acids in Blue Catfish (Ictalurus furcatus) and Channel Catfish (I. punctatus) within two central Ohio Reservoirs to help locavores make informed decisions on which type of fish to consume. Belly fillets with skin attached were collected from Blue Catfish (n=37) and Channel Catfish (n=39) in the summer and fall of 2022 from Hoover Reservoir and Channel Catfish were also collected from Alum Creek Reservoir in the summer of 2022 using short-term gill net sets. We hypothesized that beneficial fatty acid concentrations would vary with environmental seasonal changes (e.g., water temperature) and fish size and species due to differences in feeding ecology. We also expected to observe increasing concentrations of EPA and DHA with an increase in fish size. While understanding the fatty acid composition of different fishes can help locavores make informed decisions, it is dually important to conduct a risk-benefit assessment to ensure that fish have adequate levels of fatty acids while also following fish consumption guidelines to maintain a safe level of contaminant exposure.

AUTHORS: Shasta Kamara, Program of Ecology, Evolution, and Conservation Biology, University of Illinois Urbana-Champaign; Jackson Glomb, Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign; Cory Suski, Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign

ABSTRACT: American Paddlefish (Polyodon spathula) have important commercial and recreational fisheries throughout their range, which covers a wide latitudinal gradient. Seasons for Paddlefish angling and harvest are broad and often set by dates, and, as a result Paddlefish can experience capture and release across a range of temperatures. Currently, the impact of thermal variation on Paddlefish response to capture stressors has not been defined, precluding us from making informed management decisions regarding the timing and duration of angling and harvest seasons. Therefore, the objective of this study was to quantify the response of Paddlefish to simulated capture and release across a range of temperatures using two experimental approaches. In the first study, juvenile Paddlefish were acclimated to 13, 17.5, and 22° C. Fish from each of these temperatures were subjected to a simulated angling experience and recovered for 30 minutes, 4 hours, or 8 hours; a second group of fish were given a critical thermal maximum test (CTmax) to quantify heat tolerance. The second study sought to quantify post-release behavior of adult Paddlefish after simulated commercial capture at different temperatures using tri-axial accelerometers. Results from the first study showed that Paddlefish acclimated to 13°C recovered from exercise within 4 hours, while fish acclimated to 22°C did not recover, even after 8 hours. The 17.5°C and 22.0°C treatments had higher CTmax than the 13.0°C treatment suggesting an upper limit to thermal tolerance. Results thus far indicate that Paddlefish experiencing warmer temperatures have reduced performance relative to cooler fish, suggesting that temperatures over 20 degrees may be stressful for released Paddlefish after exercise. Together, these projects can help inform how Paddlefish respond to capture stressors across a range of temperatures and inform future management options to minimize impacts on individuals.

AUTHORS: Israt Jahan, Samodha Fernando, Chris Chizinski, Mark Pegg

ABSTRACT: The gut microbiome plays a vital role in the health and survival of aquatic species, including the endangered Pallid Sturgeon (Scaphirhynchus albus), which is experiencing reproductive challenges due to habitat alterations. While hatchery augmentation remains a key strategy to bolster Pallid Sturgeon populations, the reduced survival rates of hatchery-raised individuals present a significant obstacle to delisting efforts. This study investigates the gut microbiomes of wild-caught Pallid Sturgeon from Platte River and hatchery-raised Pallid Sturgeon from Gavin's Point National Fish Hatchery to identify differences and their potential management implications. Fecal samples were collected from both groups, and the 16S rRNA gene was amplified to sequence and characterize the microbial communities present. Findings indicate that wild-caught sturgeon exhibit a more diverse and adapted gut microbiome than their hatchery-raised counterparts. These differences may challenge hatchery-raised individuals in adapting to natural environments post-release, potentially affecting their survival and reproductive success. Furthermore, alterations in gut microbiota composition may influence nutrient absorption, immune function, and overall health. Integrating gut microbiome dynamics into management strategies is essential for conserving endangered species, underscoring the necessity for adaptive management approaches incorporating microbial ecology principles to ensure the long-term survival of Pallid Sturgeon populations.