2025 Midwest Fish & Wildlife Conference

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:  Daniel Isermann, USGS-Wisconsin Cooperative Fishery Research Unit; Ryan Bohen, Wisconsin Cooperative Fishery Research Unit; Daniel Dembkowski, Wisconsin Cooperative Fishery Research Unit; Alexander Latzka, Wisconsin Department of Natural Resources; Joseph Hennessy, Wisconsin Department of Natural Resources

ABSTRACT:  Bigmouth buffalo Ictiobus cyprinellus and smallmouth buffalo Ictiobus bubalus (herein buffalo) are native, non-game fishes that rarely receive management attention. Increased participation in bowfishing has prompted efforts to better understand the population dynamics of buffalo and other native fish to determine their resiliency to harvest. Buffalo are native to many water bodies in Wisconsin, but little information exists regarding their population dynamics and contribution to bowfishing harvest. Consequently, our research objectives were to: 1) describe age composition, reproductive traits, and population dynamics for buffalo populations in Wisconsin; 2) assess their resiliency to harvest, and 3) determine the contribution of buffalo to harvest at bowfishing tournaments. We collected buffalo from 14 Wisconsin waterbodies with the help of the Wisconsin Department of Natural Resources and Wisconsin Bowfishing Association (WBA). Fish were selected for age estimation using a modified age-length key approach. Lapillus and asteriscus otoliths were used for age estimation. Age structure of buffalo populations varied considerably among populations, with maximum ages ranging between 15 and 70 years. Maturation schedules also varied, with age at 50% maturity ranging between 2.0 and 6.5 years and length at 50% maturity ranging between 382 and 505 mm. Three populations were oversampled (100≤ fish) to determine the minimum number of fish in a subsample needed to fully represent age composition in the population. Bowfishing harvest was recorded at each WBA tournament in 2023 and will be recorded again in 2024. All fish brought to the weigh-in were enumerated and identified to species or species group. Contribution of buffalo to tournament harvest peaked at 70.9% at the first tournament and was lower at the next four tournaments at 10.7%, 6.0%, 0.3% and 3.5%, respectively. Our research provides fishery managers with landscape-level population information on buffalo in Wisconsin and that may help inform future management decisions.

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:  Joe Spooner, Nebraska Game and Parks Commission; Kali Boroughs, Nebraska Game and Parks Commission; Thad Huenemann, Nebraska Game and Parks Commission

ABSTRACT:  Multiple options exist to tag freshwater fish including batch marks (Visible Implant Elastomer-VIE or fin clips) and individual marks (P-Chip Microtransponders or Passive Integrated Transponder-PIT tags). Few options exist for individually marking small-bodied fish (i.e., < 100 mm TL) where upon recapture individual identification can be obtained without mortality. Nebraska is home to 26 at-risk listed fish species including many that are small-bodied. There is a lack of information on demographic rates across Nebraska on our small-bodied at-risk. To determine demographic rates through mark-recapture methods, marking techniques are required that enable individual identification, do not modify behavior or mortality of individuals, and remain readable during the duration of the study. In some cases, multiple size options are available with varying results from previous studies on post tagging fish survival and retention rates. New technology also becomes available that have minimal testing results promting the need to test multiple tag options. The objective of this study was to determine post tagging survival and tag retention for four tag types including three PIT tags (8 mm Biomark, 8 mm Voda IQ, 7 mm Voda IQ) and a newly released tag (FRyID) on Bigmouth Shiners Notropis dorsalis in a laboratory setting. Results indicated that fish survival did not differ between any of the tag types and control fish. However, tag retention was significantly lower for FRyID than PIT tags. The results of this study will provide options for use on small-bodied at-risk fish in Nebraska to monitor population demographic rates over time. Some studies may include estimating movement rates, survival, or population size. This will help managers determine their status in the state and may inform if intervention is needed.

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:  Lily Thompson, University of Missouri; Gregory Jacobs, Cornell University; Brandon Gerig, University of Wisconsin-Madison; Allison Pease, University of Missouri

ABSTRACT:  Species introductions and biodiversity loss can result in the global change phenomenon of biotic homogenization, or the process of ecological community assemblages becoming more similar to each other over time. Freshwater fish communities are understood to be particularly at risk for biotic homogenization and shifts in fish community composition can jeopardize the distinctiveness of native communities and the ecosystem services they provide. The US National Parks Service (NPS) is tasked with preserving unimpaired natural and cultural resources, including fish community assemblages. Therefore, there is a clear interest in understanding levels of biotic homogenization in the fish communities within NPS properties. We evaluated changes in fish community assemblages in midwestern National Parks using data from the NPS Heartland Inventory and Monitoring Network in two time periods: 2006–2008 and 2021–2023. Our goals were to characterize variation in fish assemblage structure among Parks, to test whether biotic homogenization has occurred over the approximately 15 years between sampling periods, and evaluate whether some Parks have shifted assemblage structure more than others. We explored both taxonomic and functional changes in local contributions to beta diversity of these sites to understand the potential for loss of unique species identities and ecosystem functions, respectively. We compared Park specific estimates of beta diversity change and assessed whether these differences could be explained by associated environmental variation. Overall, we found evidence for both homogenization and differentiation among these midwestern National Parks depending on whether taxonomic or functional homogenization metrics were used. This suggests that ecosystem function may be maintained in these locations even if the species’ identities in the fish assemblages change.

AUTHORS:  Robert Mapes, University of Toledo; Christine Mayer, University of Toledo; Song Qian, University of Toledo; Robert Hunter, US Geological Survey; Matt Acre, US Geological Survey; James Roberts, US Geological Survey; Ryan Young, US Fish and Wildlife Service; Ryan Brown, Michigan Department of Natural Resources; Lucas Nathan, Michigan Department of Natural Resources; Eric Weimer, Ohio Department of Natural Resources; John Dettmers, Great Lakes Fishery Commission

ABSTRACT:  Grass carp (Ctenopharyngodon idella) control efforts in the Great Lakes follow an adaptive management framework to continually improve removal efficiency. Initial planned action events suggested a combination of electrofishing toward trammel nets (combination method) was the most effective method to herd fish for capture. However, these initial attempts had low catches and were focused on locations with low apparent grass carp densities. Following substantial project expansion and increased effort in areas with higher apparent densities of grass carp, field crews began to experiment with other methods. A second post-hoc method comparison found electrofishing without the trammel nets to be at least >2.8 times more efficient than the combination method. The project adapted and began focusing on electrofishing while continuing to explore ways to improve efficiency by leveraging telemetry information and experimenting with other capture methods. Field crews tested passive overnight gill net sets in locations informed by telemetry and previously high capture rates. These efforts collected more grass carp in one night than the previous month of electrofishing. Expanding gill net use has contributed to more grass carp being captured during 2024 than in any other year since control efforts began in 2018. Designing a project to capture novel species with limited information is challenging and therefore an adaptive approach that analyzes data in real time is vital to invasive species control. A multi-disciplinary team with diverse skills, enables near real time incorporation of information to inform ongoing removal efforts. Although adapting to new gears has resulted in increased captures, changing methods creates challenges evaluating the effectiveness of the program through statistical models. The adaptive management framework allows for Great Lakes Grass Carp practitioners to quickly leverage data as it is collected and make concurrent changes in the field, which is invaluable to control the spread of invasive carp.

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:  Aaron Muehler, Ball State University; Amy Kinsley, University of Minnesota-Twin Cities; Nicholas Phelps, University of Minnesota-Twin Cities; Paul Venturelli, Ball State University



ABSTRACT:  Recreational anglers and boaters can be a major vector of the spread of aquatic invasive species (AIS), but movement patterns are oftentimes poorly understood due to the difficulties of collecting data. Currently, Minnesota collects movement data through statewide watercraft inspection stations. In the past these data have been leveraged to predict movement patterns of anglers and boaters. As such, these data are the current gold standard, but there may be another option. A potentially innovative and economical solution is to obtain movement data from smartphone applications (apps) in the form of angler recorded catch times and locations. Aggregate forms of these data can then be used to describe and predict the relative popularity of lakes, and the flow of traffic among them. The goal of this study was to gain insight into the ways that big data can improve predictors of pathways of AIS spread. To that end, we employed predictive modeling previously used to build a movement network with watercraft inspection data and applied it to data from a popular fishing app, Fishbrain. We found that these two networks were comparable and displayed a high level of connectivity among Minnesota waterbodies, potentially furthering the spread of AIS. Although similar, differences present likely stemmed from biases in which group of anglers were surveyed within each collection method. Simply, watercraft inspections only targeted watercraft users, while Fishbrain provided data for both shore and private access anglers, along with boaters. These insights are essential to the design and optimization of prevention, detection, and monitoring efforts for Minnesota and may allow for enhanced resource allocation. These results also provide insight into how this approach can be expanded to inform larger efforts (e.g., the Great Lakes Region, contiguous U.S.), and set the stage for future work.

AUTHORS:  Nicholas Iacaruso, University of Illinois Urbana-Champaign, Illinois Natural History Survey; Joel Corush, Illinois Natural History Survey; Mark Davis,University of Illinois Urbana-Champaign, Illinois Natural History Survey

ABSTRACT:  Aquatic invasive mollusks (gastropods and bivalves) are among the most ecologically and economically impactful groups of non-native species to the Midwest United States. They can achieve hyper-abundance in freshwater ecosystems, negatively impacting native mollusk biodiversity, damaging infrastructure, altering ecosystem characteristics, and facilitating other invaders. Early detection of new populations before they become hyper-abundant can be an effective strategy for mitigating their worst impacts. However, their small size and cryptic life history often make new invasions difficult to identify. Here, we deploy environmental DNA (eDNA) metabarcoding to detect aquatic invasive mollusks across the Illinois River waterway, an aquatic highway connecting the Mississippi River to the Great Lakes. We focused on six focal species with varying levels of establishment and distribution throughout the Illinois River. We sampled the Illinois River and 24 tributaries over two years to estimate the relative distribution of each invasive mollusk. We also performed eDNA metabarcoding to detect the native mollusk and fish communities in each tributary. We intend to find correlations between the presence of the invasive mollusks and the physical habitat measurements, land-use metrics, or native mollusks and fishes that may inform the current heterogeneous distribution of aquatic invasive mollusks. Our study will also serve as a model for studying the fine-scale spatial distribution of aquatic mollusk eDNA and aid in understanding why some tributaries are more heavily invaded than others.

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:  Adam C. Jones, US Geological Survey; Jesse R. Fischer, US Geological Survey; Josey L. Ridgway, US Geological Survey.

ABSTRACT:  There are over 40,000 dams in the Mississippi River Basin, and concentrations of invasive Silver Carp (Hypophthalmichthys molitrix) below them are well documented as populations attempt to migrate, reproduce, and establish in upstream ecosystems. Consumer-grade sonar and image analysis techniques provide an efficient and cost-effective approach to evaluate and monitor the density of invasive carp populations in these unique and intensely managed areas of interest. Current automated image analysis tools are reliable and used throughout the Mississippi River Basin to count, measure, and understand the behavior of invasive carp populations in a diversity of habitats. However, these tools are ineffective in quantifying targets within high density groups (i.e., schools), prompting the need for additional image analysis techniques and an improved understanding of the three-dimensional distributions of invasive carp individuals and concentrations. Overall, our objective is to evaluate fine-scale and reach-wide abundance dynamics through time (i.e., day, night, and season) and environmental conditions (i.e., water discharge, velocity, temperature). We conducted repeated sonar surveys using side-scan and down-imaging sonar in the Kentucky Lake and Lake Barkley tailwaters (Tennessee River and Cumberland River respectively) throughout 2023 and 2024. Four parallel transects were conducted for each 5-km reach downstream of each dam. Surveys began at the dams and moved downstream at ~8 km/h to ensure consistent images. Current data processing involves the manual identification of fish groups (i.e., area) within side-scan sonar images and the use of simultaneously recorded down-imaging sonar images to quantify depth distributions of high-density schools to estimate volumetric abundances of invasive carp. Manual processing will be used to train machine learning models similar to approaches being used to estimate individual fish targets. These results will inform future research objectives to improve survey design as well as management efforts, such as deterrence and removal actions in these critical bottleneck habitats.

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:  Christina M Mackey, US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit; Craig Paukert, US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit; Mark L. Wildhaber, US Geological Survey - Columbia Environmental Research Center; Allison A Pease, School of Natural Resources - University of Missouri; Jacob D Faulkner, US Geological Survey - Columbia Environmental Research Center; Robin D Calfee, US Geological Survey - Columbia Environmental Research Center

ABSTRACT:  In the Mississippi River Basin and Great Lakes of the USA, behavioral deterrents that utilize acoustic stimuli are being considered for deployment in rivers to deter movement of invasive carps. Grass Carp Ctenopharyngodon idella are ostariophysans that possess an inner ear connection to the swim bladder allowing them to detect a broader range of frequencies compared to non-ostariophysans. This provides the potential for a greater range of response to acoustic stimuli. Previous research demonstrated the ability of Bighead Carp Hypophthalmichthys nobilis and Silver Carp H. molitrix to avoid acoustic stimuli in the laboratory. Prior to this study, limited data were available to support avoidance of acoustic stimuli by Grass Carp. We evaluated acoustic stimuli as a deterrent for Grass Carp by exposing two naïve juvenile carp together to a recording of one of three acoustic stimuli—a 10 second chirp (0.3 – 5 kHz), continuous 100 horsepower boat motor (0.6 – 10 kHz), and 3-6 beats/second percussion (0.375 – 23.5 kHz). Trials were conducted in a 720-liter indoor tank and Grass Carp behaviors (swimming velocity, proximity among individuals, time near stimulus) were measured for 10 minutes prior to (baseline behavior) and during the presentation of the stimulus (response). Grass Carp swimming velocity was statistically similar among stimuli, though carp in percussion trials appeared to show a slight increase. Compared to baseline behavior, Grass Carp spent more in close proximity when exposed to chirp stimulus and farther apart during exposures of boat motor stimulus. All three acoustic stimuli appeared to increase the time Grass Carp spent near the stimulus source, although responses varied among trials. Preliminary results suggest that Grass Carp response to acoustic stimuli presented in this study is complex and of relatively modest magnitude. The immediate value of acoustic stimuli as a deterrent is unclear from these results and warrants further study.

AUTHORS:  Cade Roach, University of Missouri; Matthew R. Acre, US Geological Survey; Allison A. Pease, University of Missouri

ABSTRACT:  Efficient methods for estimating species abundance are critical for assessing the status of Silver Carp (Hypophthalmichthys molitrix) in the Mississippi River basin, given the ecological and economic threat this invasive species poses to water resources. Measuring Silver Carp abundance helps to characterize range expansion dynamics and evaluate management strategies. Recreational-grade side-scan sonar (SSS) offers a novel approach to monitoring fish abundance, yielding estimates comparable to traditional mark-recapture methods but at a much lower cost. Regardless of the approach used to estimate abundance, imperfect detection resulting from factors such as survey method, observer subjectivity, environmental conditions, and species behavior can lead to inaccurate estimates. N-mixture models, a suite of hierarchical regression techniques, simultaneously estimate abundance and detection probability from spatially and temporally replicated count data, addressing the issue of imperfect detection. Our study aimed to estimate the abundance of Silver Carp before, between, and after mechanical removal efforts to determine the efficacy of successive removals and characterize the ensuing population dynamics. We conducted SSS surveys in the Lamine River, a tributary of the Missouri River, before and after each of two removal efforts carried out by the Missouri Department of Conservation and the U.S. Fish and Wildlife Service in September 2024. We georectified the SSS images, used semiautomated image processing to extract counts of Silver Carp, and fit N-mixture models in frequentist and Bayesian frameworks to estimate abundance and detection probability. Here, we compare abundance estimates between different stages of the removal efforts to quantify removal success and identify trends in population dynamics. We also compare the estimates of abundance and detection, computational intensity, and measures of fit between the frequentist and Bayesian approaches. Finally, we discuss potential methods to improve the differentiation of Silver Carp from other species with similar morphology in SSS imagery.

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:  Lindsey A.P. LaBrie: Graduate Research Assistant (Ph.D.), Arkansas Cooperative Fish & Wildlife Research Unit, University of Arkansas, Department of Biological Sciences, Fayetteville, AR, 72703. Email: llabrie@uark.edu

Caleb P. Roberts: Unit Leader, U.S. Geological Survey, Arkansas Cooperative Fish & Wildlife Research Unit, University of Arkansas, Department of Biological Sciences, Fayetteville, AR, 72703. Email: cr065@uark.edu

ABSTRACT:  Preventing new invasions from occurring is the most effective way to avoid the negative ecological, economic, and societal impacts of invasive species. Two established and highly related methods for preventing new invasions are horizon scans and risk screening. Horizon scans use expert consultation and consensus building to conduct rapid risk screening. Arkansas, like the rest of the U.S., is experiencing negative impacts of invasive species, and thus, there is a critical need to prevent new invasions and thereby avoid new negative impacts. Here, we met this need through three objectives: we 1) extracted risk screening results for fish in trade from the U.S. Geological Survey’s Horizon Scan of Vertebrates in Trade and adapted these results to Arkansas, 2) used the fish species screened in the USGS Horizon Scan to determine how climate matching scores shifted under future climate scenarios, and 3) developed a standardized workflow for risk screening for aquatic nuisance species in the United States that incorporates risk of establishment under future climate scenarios. To accomplish the first objective, we pulled risk screening scores (comprised of risk of establishment, invasion history and pathways, and potential negative impacts) for the 319 fish species identified in the USGS Horizon Scan. For the second objective, we used all fish species identified and screened in the USGS Horizon Scan. Then, using future climate models (Shared Socioeconomic Pathways models) for the years 2040, 2070, and 2100, we calculated climate matching scores between potential fish invaders’ native ranges and the climate in the U.S. For the third objective, we created a future risk factor scoring protocol for risk of establishment under future climate scenarios and applied the scoring to all fish species from Objective #2. Under current and future climates, only Prochilodus lineatus and Chondrostoma nasus received high risk scores in Arkansas. However, 11 species moved from low to medium risk under future climates, reflecting increased establishment potential. Most of the species that moved from low to medium risk are known invaders outside the U.S. and are known to have strongly negative ecological impacts in their introduced ranges, such as Clarias gariepinus, Abramis brama, and Hemichromis lifalili. Although climate change is increasing the potential for invasive species to establish in Arkansas, we show that prioritizing invasive species for prevention and watchlists is still feasible as the climate changes. Species identified as medium and high risk in this project are strong candidates for in-depth risk screening summaries and adding to an invasive species watchlist for Arkansas.

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:  Braden Whisler, Eastern Illinois University; Robert Colombo, Eastern Illinois University; Daniel Roth, Eastern Illinois University; Eden Effert-Fanta, Eastern Illinois University

ABSTRACT: 
Bighead Carp (Hypophtalmichtys nobilis) and Silver Carp (H. molitrix), often referred to as bigheaded carps (BHC), have invaded many rivers throughout North America and the Mississippi River drainage. With their niche occupation and feeding habits, evidence suggests the degradation of native fish assemblages through competition. Although there are spawning populations located throughout the BHC invasion, few studies have focused on visualizing the timing and location of spawning events. The aim of this study is to examine how spawning BHC utilize tributary versus mainstem river sites throughout the year and in varying environmental conditions. From April to September of 2021-2024, BHC ichthyoplankton were collected from mainstem and tributary sites in the La Grange Pool of the Illinois River throughout an array of different environmental conditions (flood, high/low stream velocity, temperature). Consistent with previous studies, flood pulses, higher water velocities, and temperature thresholds triggered spawning events, contributing to higher densities of BHC ichthyoplankton drifting in the current. High-water years also facilitated the movement of BHC into tributary systems, contributing to spawning events and larger BHC ichthyoplankton catches in the tributaries. This study demonstrates the importance of continued monitoring of spawning conditions and timing in areas where BHC are already established. By developing predictive models for BHC spawning events in both mainstem and tributary habitats, resource managers can implement targeted removal strategies for spawning adults at invasion fronts or areas of special concern, such as the Laurentian Great Lakes. These proactive measures have the potential to significantly reduce year class sizes and mitigate the ecological impact of BHC invasions.

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.