2025 Midwest Fish & Wildlife Conference

AUTHORS: Brielle Thompson, Missouri Cooperative Fish and Wildlife Research Unit, University of Missouri;
Mike Colvin, US Geological Survey, Columbia Environmental Research Center;
Craig Paukert, US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit;
Sara Reynolds, Missouri Cooperative Fish and Wildlife Research Unit, University of Missouri

ABSTRACT: Numerous species of invasive carp are currently established in the Missouri River Basin, causing natural resource managers to grapple with complex decisions involving how to best monitor and manage invasions. A new invasive carp species, the Prussian carp (Carassius gibelio), is established in the Canadian Provinces of Alberta and Saskatchewan in waterways that provide a potential invasion pathway to the Missouri River. Prussian carp are a concern because they spread rapidly, reproduce asexually, and compete with native fish species for food and habitat. Given the risk of invasion into the Missouri River, US natural resource managers will likely need to develop early detection programs. A framework to track the Prussian carp distribution and project the spread of Prussian carp in Canadian waters is needed to inform allocation of early detection efforts in the US. We developed a dynamic multistate occupancy model that can use data from varying sources to estimate the annual distribution. The model also accounts for hydrologic and other connections among management units to project Prussian carp spread. We evaluated alternative spatial-temporal early detection plans with varying data stream combinations, including anticipated monitoring data such as eDNA data, detection/non-detection data, and presence only data. We compared alternative monitoring plans across varying levels of monitoring effort (i.e., the number of riverine management units monitored, and the types and combinations of data collected) to rank alternative Prussian carp monitoring plans. The modeling framework we developed can be applied to a variety of aquatic invasive species to inform distribution, evaluate monitoring programs within invaded areas, project spread, and inform the development of early detection programs.

AUTHORS:  Brenden Elwer, Department of Natural Resource Management, South Dakota State University; Alison Coulter, Department of Natural Resource Management, South Dakota State University; Zachary Feiner, Office of Applied Science, Wisconsin Department of Natural Resources, Science Operations Center and Center for Limnology, University of Wisconsin-Madison; David Coulter, Department of Natural Resource Management, South Dakota State University

ABSTRACT:  Preventative monitoring is an important tool for managing invasive species. Monitoring programs can detect invasions soon after introductions, allowing for rapid response actions that lead to successful containment or eradication. Individuals likely congregate in areas of highest habitat quality, so understanding how habitat quality changes through space and time can be useful for invasive species management by ensuring sampling and response efforts target locations where new invaders are likely to be present. For this work we assessed spatial and temporal trends in habitat quality for Silver Carp, Hypophthalmichthys molitrix, in currently uninvaded lakes, rivers, and wetlands in eastern North and South Dakota. We did so by calculating water temperature, water velocity, phytoplankton density, and zooplankton density from observed monthly sampling across 30 m x 30 m grid cells in each water body. Observations were then used in bioenergetics models that calculated growth rate potential, an index of habitat quality, that we compared through space and time. Developing our understanding of how high-quality habitat patches for Silver Carp shift over time enables more effective monitoring and preventative action planning for resource managers.

AUTHORS: Michael Parr, Kansas Department of Wildlife and Parks; Chris Steffen, Kansas Department of Wildlife and Parks

ABSTRACT: The transportation of aquatic invasive species (AIS) is often facilitated intentionally or unintentionally through anthropogenic activities. The commercial bait trade represents one potential pathway for AIS introductions as non-target bait species, or contaminates, can be accidently sold to anglers who may release the species while fishing or as excess bait. In order to prevent AIS introductions in the bait trade, Kansas Department of Wildlife and Parks (KDWP) developed a multifaceted commercial fish bait dealer program that encompasses both regulatory control, education, and outreach programs. Beginning in 2012, several regulations have been enacted or amended that have changed the use of bait, including commercial and wild-caught bait. These regulations have limited the allowable bait species and harvest locations, increased record-keeping and importation requirements, and changed how KDWP permits and regulates individuals involved in the commercial fish bait industry. Without direct oversight, both AIS and diseases can spread quickly with bait. Therefore, KDWP conducts annual inspections of permitted bait retailers to ensure all requirements are being met and aims to improve the retailer’s awareness of AIS issues and baitfish regulations. Most anglers who use live bait purchase it from retail bait shops, presenting a great opportunity for retailers to provide anglers with information regarding AIS awareness and prevention. Thus, during these inspections KDWP provides education and outreach materials to the bait dealers to ensure they have the resources available to educate those anglers. These inspections also give bait dealers the opportunity to have face-to-face interactions with KDWP staff and has helped them develop a positive relationship with the agency.

AUTHORS: Jason Ross, US Fish & Wildlife Service; Mark Brouder, US Fish & Wildlife Service; Aaron Murphy US Geological Survey; Mathew Walker, US Geological Survey

ABSTRACT: Member agencies of the Mississippi Interstate Cooperative Resource Association (MICRA) are actively implementing management and control actions to reduce the spread and abundance of invasive carp species that are established and expanding their range in the Mississippi River Basin. MICRA formed an Invasive Carp Advisory Committee (ICAC) to coordinate the planning, execution, and evaluation of collaborative actions to prevent, detect, and control invasive carp populations. Currently, the information and data collected and needed to evaluate the effectiveness of the various control and management actions being implemented are housed and dispersed among the individual agencies or entities. These information and data “silos” are difficult to discover and access by the various MICRA member agencies, the ICAC working groups and modelers tasked with evaluating the effectiveness of control and management efforts across the landscape, and other interested parties. The U.S. Fish and Wildlife Service and U.S. Geological Survey, working on behalf of the ICAC Data Analysis Workgroup, are developing a web-based platform known as CarpDAT (Data, Analysis and Tools) that intends to improve the discoverability and accessibility of invasive carp information and data being collected across the Mississippi River Basin by compiling and consolidating it in a single location.

AUTHORS: Michael E. Colvin, US Geological Survey; Caleb A. Aldridge, US Fish and Wildlife Service; Neal Jackson, US Fish and Wildlife Service; Max Post van der Burg, US Geological Survey


ABSTRACT: The Tennessee and Cumberland rivers (TNCR) invasive carp subbasin partnership (Partnership) comprises state and federal agencies tasked with coordinating invasive carp control efforts, identifying funding priorities, executing funded projects, and reporting project results annually. To better align subbasin program operations with management objectives the TNCR Partnership prioritized and funded a project to structure their decision making processes—our team facilitated execution of the project. Over several online and face-to-face meetings, we elicited the TNCR Partnership’s management objectives and alternative invasive carp management strategies. The TNCR Partnership produced a shared understanding of uncertainties associated with invasive carp management and monitoring, co-producing an systems model that projects the future state of invasive carp abundance and distribution. Additionally, the systems model can help the TNCR Partnership evaluate alternative management strategies by comparing whether the expected outcomes of implemented management actions align with management objectives. Varying uncertainties were identified throughout the elicitation process that could be reduced through research or monitoring. This talk focuses on how uncertainties, framed as hypotheses, can potentially be reduced by monitoring outcomes of management actions as part of an adaptive management program. Specifically, we discuss the minimal requirements to operationalize an invasive carp adaptive management program which aligns with existing funding and project management timelines. Lastly, we highlight lessons learned during this structured decision making process and provide generalizations applicable to other invasive carp subbasin partnerships.

AUTHORS: Michael Spear, Illinois Natural History Survey, Illinois River Biological Station (IRBS); Brandon Harris, IRBS; Levi Solomon, IRBS; Kris Maxson, IRBS; Andrya Whitten Harris, IRBS; Andrew Mathis, IRBS; Sam Schaick, IRBS; Jesse Williams, IRBS; Jason DeBoer, IRBS; Eric Hine, Illinois Natural History Survey, Great Rivers Field Station (GRFS); John Chick, GRFS; Jim Lamer, IRBS

ABSTRACT: The upper reaches of the Illinois Waterway are a critical containment threshold for invasive carps as they threaten to invade the Laurentian Great Lakes. Monitoring these carps – and evaluating the success of management efforts – has become the new focus of the Multi-Agency Monitoring program, a collaborative effort across state, federal, and partner agencies (discussed earlier in this session) originally designed for community-wide monitoring but recently adapted for invasive species management. Through careful analysis of the data, intentional re-allocation of resources, and effective communication across partner agencies, the MAM program has repositioned itself as a quantitative resource for evaluating the success of management efforts to contain invasive carps and prevent their entry into Lake Michigan. Here, we explore the first five years of MAM data and touch on fisheries topics including hyperstability, density-dependence, food web dynamics, and imperfect detection. A large, latitudinal gradient in carp density along the river allows for powerful space-for-time comparisons. Intense invasive carp removal efforts highlight stark contrasts between fisheries-dependent and fisheries-independent data sources. Clues from the health of the native community may offer complementary evidence for the trajectory of the invasive carp population, placing renewed value on maintaining the original community-wide sampling approach of MAM. As MAM answers this call to serve the short-term invasive species management goals, preserving the long-term integrity of its standardized sampling framework remains a priority that will require thoughtful, intentional, and iterative changes to the design and protocols of the program. Early results indicate that community-wide, fisheries-independent data such as MAM can flexibly serve shifting management priorities while maintaining long-term perspectives, a successful example of “adaptive monitoring.”

AUTHORS:  James T. Lamer; Mike Spear; Brandon Harris; Sam Schaick; Jesse Williams; Andrew Mathis; Emily Szott; Kaiden Vinavich; Levi Solomon; Kris Maxson; Andrya Whitten; Jason DeBoer, Illinois Natural History Survey; Allison Lenaerts; Eli Lampo, Illinois Department of Natural Resources

ABSTRACT:  Invasive carp can have detrimental effects on native ecosystems as they become established. Commercial and informed contracted harvest are currently the most impactful management strategies to reduce numbers and spread. However, evaluating effectiveness of this harvest to determine the proportion of the population impacted to help set management targets and allocate effort has been challenging due to invasive carp long-range movements, episodic recruitment, and difficulty obtaining population estimates through traditional means. Nevertheless, the need to assess population abundance or changes in relative abundance is still necessary to help guide and prioritize management efforts, help forecast future markets needed to grow the infrastructure and demand, and to understand dynamics and threats at the leading-edge populations. This talk provides an overview of some current invasive carp management evaluation tools being explored on the Illinois and Mississippi rivers by the state of Illinois and other state and federal partners. The choice of evaluation technique used varies depending on the state of invasion and the unique properties of each river system. In low density areas, techniques being explored include fisheries-independent monitoring in designated carp-likely habitat strata for silver carp and black carp, relative weight density-dependent baseline deviations in invasive carp and native surrogates, telemetry guided removals and harvest estimates from tagged fish in closed populations, and master chronologies to detect changes in growth over time. In high-density areas, several of the techniques used in low-density areas are combined with fisheries-independent monitoring and the resulting relative abundance estimates are grounded in density-dependent metrics while recognizing and accounting for differences in habitat strata and reach-specific structure.

AUTHORS: Kaiden Vinavich, Illinois Natural History Survey; Levi Solomon, Illinois Natural History Survey; Sam Schaik, Illinois Natural History Survey; Jesse Williams, Illinois Natural History Survey; James Lamer, Illinois Natural History Survey; Edward Sterling, US Fish & Wildlife Service, Columbia, MO; Ben Marcek, US Fish & Wildlife Service, Carterville, IL; Michael Weber, Iowa State University; Christopher Sullivan, University of Connecticut; Mark Fritts, US Fish & Wildlife Service, La Crosse, WI; Allison Lenaerts, Illinois Department of Natural Resources; Emily Szott, Illinois Natural History Survey; Zack Witzel, Minnesota Department of Natural Resources; Brandon Harris, Illinois Natural History Survey

ABSTRACT: Invasive carp, composed of bighead (Hypopthalmichthys nobilis), silver (H. molitrix), grass (Ctenopharyngodon idella), and black carp (Mylopharyngodon piceus), have negatively impacted the food webs and native biota of the Mississippi River Basin since their introduction in the late 1970s. Harvest is the primary management strategy to reduce invasive carp populations, however, due to their complicated life history and absence of robust population estimates, additional assessment tools are needed to help evaluate the effectiveness of harvest. Therefore, we are exploring variation in invasive carp annual growth as a surrogate for invasive carp density in response to management and removal efforts. This will be accomplished through two main objectives: 1) build master chronologies and characterize invasive carp annual growth within discrete, spatially-explicit management units across a spectrum of invasion densities in the Mississippi River Basin and 2) model growth response to management (harvest) and ecological/environmental drivers (e.g., zooplankton abundance, cumulative growing degree days, year-class strength, and hydrology). We will evaluate growth through incremental lapillus otolith measurements from bighead and silver carp across reaches of the Upper and Lower Mississippi River, Illinois River, Missouri River, Ohio River, and select tributaries ranging from 2014-2024 (n=50; 25 male, 25 female per species, per reach, per year). A mixed effects modeling approach will be used to estimate annual growth in response to management and external drivers, while adjusting for allometric and individual-specific growth intraclass variation. The results of this work will yield master invasive carp chronologies across their invaded range, capturing several stages of their invasion throughout the Mississippi River Basin and hopefully serve as a baseline for future collections and a tool to help evaluate management success.

AUTHORS: Adam McDaniel ¹, Thomas Boersig III ¹, Jessica Howell ², Jason Goeckler ², Jahn Kallis ², Pablo Oleiro², Kellie Hanser ², Bryon Rochon ², Edward Sterling ², & Kasey Whiteman ¹
¹ Missouri Department of Conservation; ² U.S. Fish & Wildlife Service


ABSTRACT: Invasive carp, particularly Silver Carp Hypopthalmichthys molitrix and Bighead Carp Hypopthalmichthys nobilis have expanded throughout the Mississippi River basin over the last thirty years. Studies to better understand these species and infer control measures in the Missouri River sub-basin have increased in the past several years. The Missouri Department of Conservation in collaboration with the U.S. Fish & Wildlife Service conducted intensive carp removals on two lower Missouri River tributaries with varying watersheds, the Grand River in northwest Missouri and Lamine River in central Missouri. This study evaluates the removal of invasive carp in closed and open fluvial systems, removal gears and effort to reach exploitation goals, changes in density of Silver Carp and immigration rates. Fish capture gears included experimental equipment such as the electrified paupier and dozer trawls in conjunction with standard electrofishing boats, and experimental gill nets to sample multiple habitat types. Hydroacoustic sonar surveys were conducted pre- and post-removal to quantify changes of invasive carp densities. Acoustic telemetry was also utilized to track daily movements and behavior of local Silver Carp previously implanted with acoustic tags. Removal efforts on the Grand River removed 28,848 kg of invasive carp and 17,506 Silver Carp in thirteen days of effort. Hydroacoustic density estimates indicated Silver Carp densities overall in 2023 were lower than 2022 and densities decreased each removal period in the Grand River. Missouri River tributaries most likely support all stages of invasive carp such as spawning, nursery and recruitment. Tributaries also represent areas invasive carp are probably vulnerable to overfishing as Silver Carp tend to congregate in deep slow pools and habitats easier to sample than mainstem Missouri River with faster water velocities and rock training structures. These efforts can aid biologists moving forward on future control and management actions of invasive carp in Missouri River tributaries.

AUTHORS: Jessica Howell, US Fish & Wildlife Service; Kevin Drews, US Fish & Wildlife Service; Jason Goeckler, US Fish & Wildlife Service; Adam McDaniel, Missouri Department of Conservation; Joe McMullen, Missouri Department of Conservation; John Schulte, Missouri Department of Conservation; Kasey Whiteman, Missouri Department of Conservation; Liam Odell, Kansas Department of Wildlife and Parks; Chris Steffen, Kansas Department of Wildlife and Parks; Brett Anderson, University of Nebraska at Lincoln; Kirk Steffensen, Nebraska Game and Parks Commission; Matt Acre, US Geological Survey; Jesse Fischer, US Geological Survey; Josey Ridgway, US Geological Survey;

ABSTRACT: Given the widespread impacts of Silver Carp in areas where they have become established, a focus on effective management strategies for this invasive fish has increased in recent years. State and federal research and management agencies have been working nationwide to identify effective control methods such as deterrents to limit distribution, conduct removals to reduce abundance, and research and develop novel management techniques. In the Missouri River Basin, Silver Carp have invaded over 1,300 kilometers of the Missouri River and numerous tributaries along that stretch, representing a large and diverse set of challenges for managers. The Missouri River Basin Invasive Carp Partnership of State, Federal, and University partners collaborate to address this interjurisdictional challenge for the basin. In addition to projects aimed at better defining the risk and delineating populations, Missouri River Basin partners are focused on developing and refining gears and techniques to limit Silver Carp distribution and abundance. The Partnership seeks to integrate successful strategies from other river basins as well as to innovate new approaches, including developing and testing sonar and modeling techniques to estimate populations, refining herding techniques to concentrate and remove fish, working to assess interest in commercial fisheries, testing intensive versus sustained agency removal efforts, and more. By developing and testing multiple strategies, effective techniques and approaches can be applied across this highly diverse and dynamic system to elicit a population-level impact. Population assessments and delineations being conducted concurrently can direct management efforts to where they will be most effective as well as measure the effectiveness of deterrents and exploitation placed across the landscape. This presentation will highlight collaborative research and management efforts from the Missouri River Basin Invasive Carp Partnership and the results of recent efforts.

AUTHORS: Authors: Josh Abner
Affiliation: Missouri Department of Conservation

ABSTRACT: Abstract: Invasive bigheaded carp (Silver Carp and Bighead Carp) have been around for decades, with populations continually growing and expansion continuing to take place. Funding, as well as consequent research and removal efforts have vastly increased among recent years. The Missouri Department of Conservation (MDC) has taken advantage of this to not only learn more about these fish and their impacts but to also focus on removal efforts and strategies. Invasive bigheaded carp have been implanted with acoustic transmitters across the state of Missouri within the Upper Mississippi River, the Lower Mississippi River, and the Missouri River basins, to track movement patterns in response to removal efforts. Collaboration with other state and federal agencies allows us to further our project scope with minimal additional effort. Standardized fish community assessments are also taking place to begin collecting long term trend data to elucidate community changes to invasive carp removal. A multi-sub-basin project approach related to research and removal is the kind of broad scale collaboration that will be required to make a difference in invasive bigheaded carp control and management.

AUTHORS: Joshua Tompkins, Kentucky Department of Fish and Wildlife Resources; Matthew Dollenbacher, Kentucky Department of Fish and Wildlife Resources

ABSTRACT: Prior to the invasion of bigheaded carps into Kentucky waters’ there was a rich history of commercial fishing. This presentation will be a road map of how Kentucky Department of Fish and Wildlife Resources, developed a robust invasive carp harvest industry by leveraging preexisting commercial infrastructure, recruiting new partners into the process and engaging stakeholders to enact regulations to allow for less restrictive regulations with the aim at reducing invasive carp populations and limiting range expansion. Other aspects of the industry development, economics and public input about the perception of how these programs and initiative have towards successful meeting KDFWR goals, will be highlighted throughout.

AUTHORS: James E. Garvey, jgarvey@siu.edu, Center for Fisheries, Aquaculture, and Aquatic Sciences, School of Biological Sciences, Southern Illinois University, Carbondale, IL, USA
Kevin S. Irons, Illinois Department of Natural Resources, Springfield, IL, USA
Gina Behnfeldt, Tetra Tech, Langhorne, PA, USA

ABSTRACT: Invasive bigheaded carps (Hypophthalmichthys spp.) threaten rivers of the central US, the Great Lakes, and potentially other drainages in North America. A pilot commercial fishing incentive program was initiated in the lower Illinois River in 2012 to help control carp populations, which rapidly removed 1,500 tons of biomass. In 2019, a modified incentive program began and has expanded to other invaded river basins. In 2022, a branding and marketing effort named the seafood product derived from bigheaded carp as Copi, allowing consumers to recognize these fishes as an environmentally sound and responsible alternative to other seafood choices in North America. The Copi brand has gained interest nationwide, with food processors and distributors engaged. A total of 7,650 tons of Copi have been removed from the Illinois River and Ohio River Basins. The challenge will be to develop a self-supporting regional fishing industry that controls and contains these fishes while also aiding fisheries and aquaculture for native species.

AUTHORS: Mark Morgan, School of Natural Resources, University of Missouri

ABSTRACT: The prevalence of malnutrition is high and growing at an alarming rate in developing countries. Countless women and children suffer from anemia, stunting and/or wasting due to a low intake of protein and other essential nutrients. Use of invasive species is a promising, but overlooked strategy to address food security. The Mississippi River Basin has been affected negatively by the spread of silver and bighead carp since their introduction in the early 1970s. Invasive carp are overly abundant in many watersheds, yet few efforts have focused on population reduction since domestic markets are scarce. Consumption is a viable option, but Americans often think of silver and bighead carp as trash fish. As a result, many of them are thrown into landfills or turned into low value products such as fertilizer or animal feed. However, lab tests show that invasive carp are among the most healthy and nutritious freshwater fish in the U.S. In powdered form, they contain a unique profile of nutrients and vitamins that are needed for human health and brain development. Use of silver carp as a food ingredient is one solution to increase the nutritional benefits of child-bearing women and young children, especially for infants in the first 1,000 days of life. The goal of Eat MO Carp is to produce a complementary food using silver carp to address food security and malnutrition at home and abroad, thus helping to restore Midwest rivers.

AUTHORS: Max Monfort, University of Wisconsin La Crosse US Geological Survey Upper Midwest Environmental Science Center; James Wamboldt, US Geological Survey Upper Midwest Environmental Science Center; Matthew Acre, US Geological Survey Columbia Environmental Research Center; Andrew Mueller, US Geological Survey Columbia Environmental Research Center; Dustin Broaddus, US Geological Survey Columbia Environmental Research Center; Jacob Griffin, US Geological Survey Columbia Environmental Research Center; David Schumann, University of Wisconsin La Crosse

ABSTRACT: Grass Carp (Ctenopharyngodon idella) consumption of aquatic macrophytes can alter trophic dynamics when introduced to new aquatic ecosystems. Increased commercial captures and expansion into further reaches of the Upper Mississippi River (UMR) could have negative affects to these aquatic ecosystems. Efforts to control this highly mobile and illusive species in the UMR and Great Lakes Basins are a substantial challenge to managers. A potential bait for Grass Carp has been evaluated at other invasion fronts (e.g., Lake Erie), but its application in the UMR has not yet been fully recognized. We refined methods and utilized 2023 longitudinal movement data to describe the utility of automated bait delivery systems to aggregate Grass Carp in pool 19 of the UMR in 2024. Specifically, our objectives were to: (1) describe Grass Carp movement ecology within the riverscape before, during, and after bait application, and (2) determine Grass Carp movement responses to baiting; use of the baiting area, time occupied at baiting area, and the effective attraction distance from the baiting area. Grass Carp (n = 90) behavior was evaluated in response to the deployment of a novel Grass Carp specific bait via automated bait delivery systems in four distinct habitats using acoustic telemetry arrays from March-November 2024. If successful, these methods could provide an exploratory, yet innovative, Grass Carp management strategy for more efficient removals within the UMR and other invasion fronts.

AUTHORS: Kroboth, P. T., M. E. Colvin, C. L. Broaddus
U.S. Geological Survey, Columbia Environmental Research Center, Columbia, MO 65201


ABSTRACT: Black Carp Mylopharongodon piceus were imported into the United States in the 1980s for use in aquaculture. Since then, escapes have occurred and reported wild captures have increased. Black Carp are a concern because of potential impacts on native ecosystems and direct predation on native imperiled mollusks. Based on commercial captures, hoop nets set in mainstem riverine habitats of the Mississippi River during spring and summer are a potential capture method. We assessed commercial fisheries Black Carp catches by kernel density analysis to identify an area of increased catch. Within this area we assessed the seasonality and rate of commercial captures, and tested targeted hoop net effort for Black Carp during 2021 and 2022. We compared Black Carp catch and co-occurring species using non-metric multi-dimensional scaling. We fit Black Carp catch and environmental covariates by general linear models: Poisson, negative binomial, zero-inflated Poisson, zero-inflated negative binomial, hurdle Poisson, and hurdle negative binomial, with the top fitted models selected based on ΔAIC < 2. The model set was refitted for predictions and inference on the model confidence set. Hoop net captures were 63% of commercial records (n=759). The confluence of the Missouri and Mississippi rivers had the greatest density of commercial captures with 39% of hoop net captures in this area, primarily during July-September. Captures were characterized by median water temperature 26.7°C, median river stage 5.02 m, and median day of year 231 (DOY; mid-August). Ordination identified similarity in covariates of Smallmouth Buffalo Ictiobus bubalus and Black Carp catch. Most captures occurred in select outside-bend or secondary-channel habitats. The probability of capturing ≥ 1 Black Carp increased with depth, DOY through September, and declined with increasing current velocity. Results indicated catch was maximized in summer and early fall when stage and current velocity are lower allowing net sets in deeper areas.

AUTHORS: Jesse R. Fischer, US Geological Survey; Josey L. Ridgway US Geological Survey

ABSTRACT: Several technologies were recently developed by the U.S. Geological Survey (USGS) to provide managers and researchers with cost-effective solutions to assess, deter, and capture invasive Silver Carp (Hypophthalmichthys molitrix) populations. These tools and techniques were designed to exploit the unique physiological and behavioral characteristics of Silver Carp. Specifically, Silver Carp exhibit strong schooling, jumping, and net-avoidance behaviors that have often created challenges for traditional methods of capture. Research on Silver Carp from a variety of habitats and population densities throughout the Mississippi River Basin has demonstrated a widespread need to create new methods to capture, deter, or control these invasive populations. Nets were developed to target low-to-intermediate densities of invasive carp by eliciting jumping while limiting bycatch. Surface-floating gill nets provide a cost-effective tool for assessing and monitoring invasive carp populations (e.g., population assessment, capturing individuals for telemetry studies). For high density populations, a corral net was designed and tested for concentrating large biomasses of fish with an emphasis on preventing escape and maintaining survival until removal. Both novel nets were designed to be used in conjunction with substrate-to-surface block-nets that can control and direct movements of individuals. Additional tools to be used with these nets include deployable underwater speakers with remote operation capabilities. These mobile acoustic deterrents were created and assessed for modifying invasive carp behavior, such as, stimulating jumping or directing movement towards areas for increased capture. Semi-autonomous watercraft were also designed and extensively field-tested to assist with invasive carp assessment and monitoring using consumer-grade sonar to estimate abundance and biomass and control strategies using remotely operated stimuli (e.g., acoustic, bubbles, lights) to concentrate fish or to elicit jumping for capture objectives. Future work will continue to demonstrate and transfer new technologies to non-USGS partners to accomplish research and management objectives across subbasins within the Mississippi River.

AUTHORS: P. Ryan Jackson, U.S. Geological Survey; Vindhyawasini Prasad, University of Illinois at Urbana-Champaign; Henry F. Doyle, University of Illinois at Urbana-Champaign; Amy E. George, U.S. Geological Survey; Cory D. Suski, University of Illinois at Urbana-Champaign; Benjamin H. Stahlschmidt, U.S. Geological Survey; Jesse R. Fischer, U.S. Geological Survey; Duane C. Chapman, U.S. Geological Survey; Anne M. Herndon, U.S. Geological Survey; Curt G. Byrd, U.S. Geological Survey; Rafael O. Tinoco, University of Illinois at Urbana-Champaign

ABSTRACT: Management of invasive carp populations in North America has long relied on harvest of adult fish. However, to effectively suppress population growth, it may be necessary to harvest invasive carp at multiple life stages, including ichthyoplankton (eggs and larvae). Despite substantial advances in understanding invasive carp reproduction requirements over the past decade, management agencies currently lack the necessary tools to control early life stage invasive carp and reduce recruitment and dispersal. An interdisciplinary team of biologists, hydrologists, and engineers has spent the past three years developing and testing a method for passive capture of invasive carp eggs and larvae drifting downstream in an open channel without disruption to navigation or conveyance. Inspired by microplastic collection systems deployed in Europe, this novel method uses a bubble screen to induce secondary flows in the channel, which redirect invasive carp eggs and larvae to passive collection gears. This presentation will summarize the results of this study to date, discuss new methods for experimentation with preserved eggs and surrogates, discuss the challenges of passive capture of ichthyoplankton in open-river conditions, and present our ongoing research and vision for the future of this emerging technology. Furthermore, insights gained from this study can inform the design of physics-based egg and larval traps, both with and without bubble screens, for monitoring and early detection. The potential for application to passive ichthyoplankton monitoring with improved probability of detection will also be discussed.

AUTHORS: Janice L. Albers, Jessica C. Stanton, Andrea K. Fritts, U.S. Geological Survey Upper Midwest Environmental Sciences Center; Nicholas Swyers, Matthew D. Sholtis, U.S. Geological Survey Western Fisheries Research Center, Columbia River Research Laboratory; Jon Vallazza, Dan Gibson-Reinemer, U.S. Geological Survey Upper Midwest Environmental Sciences Center; Theodore R. Castro-Santos, U.S. Geological Survey Eastern Ecological Science Center; Christa M. Woodley, U.S. Army Engineer Research and Development Center; Marybeth K. Brey, U.S. Geological Survey Upper Midwest Environmental Sciences Center

ABSTRACT: Invasive bigheaded carps, with their unique hearing specialization, exhibit behavioral responses to underwater acoustic signals. This intriguing behavior has prompted further research into whether these signals could be used to deter invasive carps from moving into sensitive areas or further upstream. Preventing or slowing movements of invasive carps around movement bottlenecks, such as navigation locks and dams, can minimize propagule pressure in upstream locations and provide additional time and opportunity for removal or other management actions while also minimizing impact on native species. Testing of underwater acoustic signals at large, management-relevant scales is a necessary step in determining the feasibility of this tool for long-term management of invasive carps. We evaluated an underwater acoustic deterrent system (uADS) installed in the downstream approach of the navigation lock at Lock and Dam 19 on the Mississippi River near Keokuk, Iowa. We analyzed the movement behaviors of invasive carp (bighead, silver, and grass carp) and various native species, implanted with acoustic transmitters, in relation to the uADS operation status and environmental covariates. Using multiple analytical approaches, we assessed the impact of the uADS on upstream lock passage; the rate that fish enter and exit various zones in the lock approach; and movement behavior around the deterrent. Results from this study will inform managers about the effectiveness of a uADS at preventing upstream lock passage by invasives relative to native fish species, movement behavior of fish as they interact with the deterrent and lock structure, and logistics and maintenance of uADS installations.

AUTHORS: Liam Odell, Kansas Department of Wildlife and Parks; Chris Steffen, Kansas Department of Wildlife and Parks

ABSTRACT: Introduced invasive carp have become established throughout the Missouri River basin. The feeding habits, population densities, and interactions with river users cause significant ecological damage as well as lower the desires to use bodies of water with established invasive carp populations. The Kansas River is a major tributary of the Missouri River and is one of three publicly accessible and navigable waterways in the state of Kansas. Upstream from the Kansas River are several large reservoirs that are highly utilized for outdoor recreation such as fishing, boating, nature watching, etc. The Bowersock Dam serves as a critical control point for the management of invasive carp in the Kansas River system. Only six bighead carp have been documented upstream of this structure. These six bigheads were previously assumed to have passed over the Bowersock Dam during an extreme flood event in 1993 (120,000 cfs). A recently completed study has raised concerns that invasive carp can pass over the Bowersock Dam at much lower flows (25,000 cfs). Kansas Department of Wildlife and Parks will integrate a physical deterrent at the Bowersock Dam to prevent invasive carp from moving over the dam and making their way upstream into reservoirs and the rest of the Kansas River.

AUTHORS: Brett Anderson, Nebraska Cooperative Fish and Wildlife Research Unit, University of Nebraska-Lincoln; Jonathan J. Spurgeon, U.S. Geological Survey, Nebraska Cooperative Fish and Wildlife Research Unit, University of Nebraska-Lincoln.

ABSTRACT: Silver Carp Hypophthalmichthys molitrix and Bighead Carp H. nobilis (hereafter bigheaded carp) have invaded tributaries to the Missouri River and Platte River in Nebraska. Herding is a method used to increase the capture efficiency and detection probability of adult bigheaded carp by using active and passive sampling gears simultaneously. Nevertheless, more information is needed about how herding can be applied to mid-order rivers and how it compares to more conventional methods such as electrofishing. During June-July 2023, four herding techniques were assessed regarding their ability to elicit directional movement past an enclosure gate. Herding using an underwater speaker and pulsed-DC electrofishing proved effective at directing bigheaded carp into a capture area. From June-August 2024, herding was conducted on three tributaries to the Missouri River and one tributary to the Platte River to assess the effectiveness of gill-net sets at removing fish from a capture area. Herding and standard electrofishing were assessed based on catch rates, labor hours, and crew sizes. The results of this study will provide managers, researchers, and stakeholders knowledge regarding efficient and cost-effective sampling strategies for invasive bigheaded carp that enable assessments of presence and population status as well as provides control options for population reduction and potential removal.

AUTHORS: Josey L. Ridgway, U.S. Geological Survey; Jesse R. Fischer, U.S. Geological Survey; Jessica M. Howell, U.S. Fish and Wildlife Service; John Schulte, Missouri Department of Conservation; Adam C. Jones, U.S. Geological Survey; Jason M. Goeckler, U.S. Fish and Wildlife Service; Robin D. Calfee, U.S. Geological Survey.

ABSTRACT: Invasive Silver Carp (Hypophthalmichthys molitrix) populations can reach extremely high densities and severely affect biodiversity and ecosystem function. There are currently few sampling or monitoring techniques available to natural resource managers that reliably quantify population responses to management actions. Consumer-grade sonar offers a cost-effective approach for mapping distributions and evaluating density before and after intensive control efforts. Recent advancements in consumer-grade technologies have vastly improved resolution and dependability sufficient for fisheries research and management. We developed cost efficient semiautonomous watercraft for surveying fish and aquatic habitats by combining low-cost, consumer-grade technology (i.e., sit-on-top kayaks, electric trolling motors, side-scan sonar). Semiautonomous watercraft are advantageous for surveys of invasive Silver Carp populations because of GPS-guidance capabilities with consistent tracking and speed, quiet propulsion system to minimize fish disturbance, and the potential to deploy multiple survey vessels for increased survey efficiency, while minimizing the effect of fish movements. We used two semiautonomous watercrafts to conduct repeated surveys on a population of Silver Carp in Creve Coeur Lake, St. Louis, Missouri, USA (130-ha oxbow lake of the Missouri River). Surveys were conducted at night (≥1h after sunset) and were 2-h in duration. We used an image-analysis software to automate fish target detection and size estimation to estimate density and biomass. Fish targets in side-scan sonar imagery were apportioned by size using fish community capture data collected using electrified trawl that was conducted approximately one week after seasonal surveys. Bathymetry data were used to convert counts to fish density (number)/volume (m3) and biomass (kg)/volume (m3). Preliminary estimates suggest Silver Carp biomass was over 228,600kg. Repeated surveys will be used to assess variability among estimates and to determine which season is optimal (e.g., limiting fish-boat avoidance) for standardizing future Silver Carp surveys. Final population estimates will assist in establishing harvest objectives for Creve Coeur Lake.

AUTHORS: Kellie Hanser, U.S. Fish and Wildlife Service; Jessica Howell, jessica_howell@fws.gov; Jason Goeckler, jason_goeckler@fws.gov

ABSTRACT: Silver Carp (Hypophthalmichthys molitrix) relative abundance and demographic information is essential to guide management and control measures. Interconnection across river basins has allowed Silver Carp to establish a reproducing population along the entirety of the free-flowing portion of the Missouri River and its tributaries. Population information is being collected with an electrified dozer trawl to establish baseline invasive carp data in tributary confluences to monitor populations and guide management efforts as they begin to increase. Because Silver Carp are located throughout the Missouri River, tributaries are sampled along a large spatial gradient (river miles 170 – 800) to help track and delineate populations trends across the basin. From 2020 – 2023, a total of 611 transects have been completed collecting over 29,000 individuals from 50 different species. However, most fish sampled are invasive carp with the total number of individuals exceeding 15,000. Data shows that Silver Carp across tributaries are demographically similar, with large older individuals in the higher latitude tributaries. Age data indicates the 2019-year class is still currently dominant across the basin. Annually, the relative abundance, size structure, body conditions, sex ratio, age structure, recruitment, growth, and mortality are analyzed and provided through the Missouri River Basin Invasive Carp Partnership in a collaborative effort to help inform the Silver Carp status for the basin.

AUTHORS: Tammy M. Wilson, U.S. Geological Survey - Columbia Environmental Research Center
Michael E Byrne, Department of Natural Resources, University of Missouri, Columbia
Thomas W. Bonnot, Department of Natural Resources, University of Missouri, Columbia
Robin D Calfee, U.S. Geological Survey - Columbia Environmental Research Center
Matthew R Acre U.S. Geological Survey - Columbia Environmental Research Center

ABSTRACT: Grass carp (Ctenopharyngodon idella) are nonnative, herbivorous freshwater fish that represent an invasive, ecological threat in North American waters. They originate from eastern Asia, consume large amounts of aquatic vegetation, and establishment in novel waters can cause significant ecosystem changes. There is particular concern for grass carp establishment within the Lake Erie basin, where multi-jurisdictional grass carp removal efforts have been ongoing since 2017 to reduce Lake Erie's population and the chance of dispersal to the rest of the Great Lakes. However, effectiveness of removal efforts has yet to be quantified. Grass carp in Lake Erie are data-limited as catch numbers are < 100 per year. Therefore, we used multiple length-based stock assessment methods to evaluate if removal efforts were sufficient to reduce population size. We used a combination of length-based indicators (LBI), the length-based spawning potential ratio (LBSPR), and the length-based Bayesian biomass estimation (LBB) method to assess the stock. Although these length-based methods run on the assumption of a stock at equilibrium rather than a potentially growing population, by using multiple length-based methods to assess this stock, we worked to minimize biases that may have occurred. Preliminary results highlight the absence of immature removals and indicate that removal efforts may need to target smaller fish to collapse the population.

AUTHORS: Dillon Weik, University of Toledo; Christine Mayer, University of Toledo; Tammy Wilson, US Geological Survey; Ryan Young, US Fish & Wildlife; Eric Weimer, Ohio Department of Natural Resources; John Dettmers, Great Lake Fishery Commission

ABSTRACT: Invasive grass carp have been captured in Lake Erie since the mid-1980s, and spawning in tributaries to the lake was confirmed in 2015. In response, a multi-jurisdictional partnership was established to target grass carp for removal with increasing effort since 2017. However, capture data is limited, making supplemental biological data, such as growth histories estimated from bony structures, especially useful in describing trends in the population or individual traits. Age was estimated using vertebrae for all fish removed from Lake Erie since 2012, and growth was back-calculated using the Biological Intercept Model. The back-calculated growth was then fitted to a Von Bertalanffy Growth Function. Lake Erie grass carp age-at-maturity (as indexed by a decrease in growth rate) of diploid fish was estimated to be ~3 years. In contrast, literature derived age-at-maturity ranges from 1-10 years. Current removal methods select fish > 880 mm (age-4). Consequently, recruitment may occur before fish are vulnerable to removal. Therefore, future efforts are needed to target smaller fish by exploring alternative habitats or examining new sampling gears to remove these cryptic individuals before they are able to successfully recruit to the population.