Midwest Fish & Wildlife Conference 2019

AUTHORS: Austen Thomas, Smith-Root; Samantha Stanton, Michigan State University; Jake Ponce, Smith-Root; Mieke Sinnesael, Biomeme; Phong Nguyen, Smith-Root; Caren Goldberg, Washington State University

ABSTRACT: Environmental DNA (eDNA) detection of aquatic invasive species using PCR is a powerful new tool for resource managers, but laboratory results often take weeks to be produced which limits options for rapid management response. To circumvent laboratory delay, we combined a purpose-built eDNA filtration system (ANDe) with a field DNA extraction and handheld qPCR platform (Biomeme) to form a complete field eDNA sampling and detection process. A lab study involving serial dilution of New Zealand mudsnail eDNA was conducted to compare the detection capabilities of the field system with traditional bench qPCR. Two field validation studies were also conducted to determine if the on-site eDNA process can be used to map mudsnail eDNA distribution and quantify temporal fluctuations. Both platforms (Biomeme, bench qPCR) lost the ability to reliably detect mudsnail eDNA at the same dilution level (10^-4), with SQ values as low as 21 DNA copies/reaction. A strong relationship was observed between the average Cq values of the two platforms (slope = 1.101, intercept = - 1.816, R²= 0.997, P < 0.001). Of the 80 field samples collected, 44 (55%) tested positive for mudsnail eDNA with Biomeme, and results identified both spatial and temporal fluctuations in mudsnail eDNA/L. However, the PCR inhibition rate (no IPC amplification) with Biomeme was 28% on average for field samples, and up to 48% in the temporal dataset. With additional optimization of the DNA extraction process, the ANDe-Biomeme system has potential to be a rapid and highly effective detection/quantification tool for aquatic invasive species.

AUTHORS: Mark Davis, Illinois Natural History Survey; Amanda Curtis, University of Illinois; Jeremy Tiemann, Illinois Natural History Survey; Sarah Douglass, Illinois Natural History Survey; Eric Larson, University of Illinois

ABSTRACT: The efficacy of environmental DNA to assay the presence of invasive species hinges upon understanding the covariates influencing fate and transport. In lotic systems, these covariates may include biotic (e.g. invasive species density, seasonal activity patterns, etc.) and abiotic (e.g. stream discharge, temperature, ultraviolet irradiation, pH, etc.) factors, as well as their complex interactions. To better understand fate and transport of eDNA in complex lotic systems, we assessed eDNA copy number for invasive Asian clams (Corbicula spp.) in paired freshwater streams in central Illinois via a primer/probe assay. We collected eDNA samples approximately every two weeks for one year, as well as during periods of high and low discharge. At each sampling period, we collected data for a number of water quality variables (including pH, temperature, turbidity, conductivity, total dissolved solids, and salinity), and we also conducted mid-summer quadrat sampling at each site to estimate Corbicula densities. Importantly, we placed our two sampling sites at USGS stream gages in order to access continuous discharge data. We anticipated that high stream flow events could either dilute eDNA concentrations or increase eDNA concentrations by mobilizing Corbicula DNA from the sediments. We found abundance of Corbicula eDNA as copy number increased with increasing water temperatures, likely reflecting a late spring and early summer reproductive peak for this species. However, we found a weak and non-significant negative relationship between stream flow and Corbicula eDNA abundance, despite having sampled at base flow and high flow conditions across multiple seasons. As such, we conclude that stream discharge may have little effect on estimates of eDNA abundance for common stream and river species like the invasive Asian clam, although more studies should seek to evaluate the role of stream and river flow regimes on eDNA performance.

AUTHORS: Christopher M. Merkes, US Geological Survey; Katy E. Klymus, US Geological Survey; Richard F. Lance, US Army Corps of Engineers; Emy Monroe, US Fish & Wildlife Service; Catherine A. Richter, US Geological Survey; Caren S. Goldberg, Washington State University; Antoinette J. Piaggio, USDA Animal and Plant Health Inspection Service; Chris C. Wilson, Ontario Ministry of Natural Resources; Joel P. Stokdyk, Margaret E. Hunter, Nathan L. Thompson, Craig A. Jackson, Jon J. Amberg – US Geological Survey

ABSTRACT: Many advances have been made over the last ten years in the field of environmental DNA, and new assays exist for a wide range of target species of interest.  As this technology matures, it is necessary to make methods more standardized to allow better comparisons across studies and enable meta-analysis of species distributions.  One key aspect where this may be possible is with assay sensitivity.  Sensitivity is a critical measure especially when comparing data from multiple markers, and it can be easily described in two measurements: Limit of Detection (LoD; the lowest concentration that can reliably be detected) and Limit of Quantification (LoQ; the lowest concentration that can reliably be quantified).  To facilitate this, an R script has been developed to allow a person with minimal R-coding ability to easily and reliably analyze their data to determine LoD and LoQ of their assays as well as automatically generate plots of their data that puts the values into context for easy understanding.  Putting eDNA assay results into a standardized framework and enabling end users to understand the results more clearly will enhance the value of eDNA data and facilitate its wider application.

AUTHORS: Emy Monroe, Erica Mize – U.S. Fish and Wildlife Service; Richard Erickson, Christopher Merkes – US Geological Survey; Nicholas Berndt, Katherine Bockrath, Jeena Credico, Nikolas Grueneis, Jenna Merry, Kyle Mosel, Maren Tuttle-Lau, Kyle Von Ruden, Zebadiah Woiak, Kelly Baerwaldt, Sam Finney – U.S. Fish and Wildlife Service; Jon Amberg, US Geological Survey

ABSTRACT: Natural resource managers use data from survey or monitoring efforts that use a wide variety of tools. Environmental DNA (eDNA) is a genetic surveillance tool for detecting species and holds potential as a tool for large-scale monitoring programs.  Two challenges of eDNA-based studies are imperfect capture of eDNA in collection samples (e.g., water field samples) and imperfect detection of eDNA using molecular methods (e.g., quantitative PCR), which create uncertainty about sample designs for eDNA-based monitoring.  We used an occurrence model to address these challenges and determine how many  samples were required to detect species using eDNA and to examine when and where to take samples.  Water samples were collected from three different habitat types in the Upper Mississippi River when both Bighead Carp and Silver Carp were known to be present based on telemetry detections.  Each habitat type was sampled during April, May and November.  Detections of eDNA for both species varied across sites and months, but were generally low, 0 - 19.3% of samples were positive for eDNA.  Additionally, we found statistical artifacts where sample eDNA capture probabilities would artificially inflate estimates of molecular detection probabilities.  Overall, we found that eDNA-based sampling holds promise to be a powerful monitoring tool for resource managers, however, limitations of eDNA-based sampling include different biological and ecological characteristics of target species as well as aspects of different physical environments that impact the implementation of these methods.

AUTHORS: Christopher B. Rees, Theodore W. Lewis, Sandra Keppner, Joshua Newhard, Aaron P. Maloy, Meredith L. Bartron – U.S. Fish & Wildlife Service

ABSTRACT: Populations of Northern snakehead (Channa argus) have been introduced in the Lower Hudson, Bronx, and Rondout watersheds of New York, Lower Delaware watershed of Pennsylvania and New Jersey, and the Lower Susquehanna watershed of Pennsylvania and Maryland. Because these observations are in close proximity to Great Lakes tributaries, Northern snakehead constitute a species of high invasion concern for natural resource agencies of Great Lakes connected waters. Traditional gear capture of Northern snakehead at low densities in their established range can be difficult due to the shallow, vegetation-rich habitat they typically occupy. As a result, significant environmental DNA (eDNA) detection efforts by the U.S. Fish and Wildlife Service and partner agencies in portions of the Oswego River drainage and canal system of New York have been explored. In any eDNA detection effort, it is important to have confidence in the accuracy of the markers used, and particularly when the effort involves the detection of aquatic invasive species where management and/or response actions may be taken. Here we highlight results from validation and comparative performance testing of several eDNA markers designed to detect Northern snakehead DNA and detection results of the 2018 environmental sampling efforts.

AUTHORS: Richard F Lance, Environmental Laboratory, US Army Engineer Research & Development Center; Xin Guan, Bennett Aerospace; Emy M. Monroe, Katherine D. Bockrath, Erica L. Mize – Whitney Genetics Laboratory, Midwest Fisheries Center, U.S. Fish and Wildlife Service; Chris B. Rees, Northeast Fishery Center, U.S. Fish and Wildlife Service; Kelly L. Baerwaldt, Midwest Fisheries Center, U.S. Fish and Wildlife Service

ABSTRACT: The Black Carp, Mylopharyngodon piceus, is an invasive species within the Mississippi River drainage that appears to be undergoing population growth and range expansion. Black carp are molluscivores that potentially threaten significant components of North America's rich indigenous diversity of freshwater bivalves. In order to help determine the presence of black carp in various waters and habitats, and to help track its spread, we have developed a suite of environmental DNA (eDNA) markers for this species. The markers were developed using whole mitochondrial genomes from 29 black carp from three countries and target three different mitochondrial DNA genes. The markers were further tested for reliability with a total of 41 black carp DNA samples and for specificity against DNA from numerous co-occurring fish species and against samples of natural waters free of black carp. Further tests to detect black carp in natural waters proved challenging, but ultimately successful. We further report on studies of which water fractions contain the bulk of black carp eDNA (the answer appears to be largely habitat dependent) and on the efficiency of different sampling options.

AUTHORS: Catherine A. Richter, Katy E. Klymus, Nathan Thompson, Jeffrey C. Jolley, Duane C. Chapman – U.S. Geological Survey; PRESENTER: Rick Lance

ABSTRACT: Creve Coeur Lake is a large natural floodplain lake intermittently connected to the Missouri River near St. Louis, Missouri. The lake has been invaded by Bighead Carp (Hypophthalmichthys nobilis) and Silver Carp (Hypophthalmichthys molitrix), collectively known as Bigheaded Carp. Both are native to Asia. The invasion has resulted in impairment of the native crappie (Pomoxis spp.) fishery, and hazards to recreational users. Fish can enter the lake from the Missouri River only during high water events. During the winter of 2017-2018, an intensive removal effort was conducted using the unified fishing method. A total of approximately 108,129 kg of Bigheaded Carp was removed from the lake in February 2018. Monitoring of Bigheaded Carp environmental DNA (eDNA) concentrations was conducted at intervals before and after the removal effort. Water was sampled at 53 locations equally spaced along transects covering the entire surface area of Creve Coeur Lake, a smaller upstream connected lake (Mallard Lake), and the channel between the two lakes. We measured eDNA concentrations with quantitative PCR using two marker sets specific to the genus Hypophthalmichthys, and thus able to detect and quantify DNA from both species with equal efficiency. Our results showed a decrease in eDNA concentration with decreasing water temperature over three sampling events before the removal effort, in October 2017, November 2017, and January 2018. After the removal effort, we observed an increase in eDNA in March 2018, possibly resulting from the presence of injured fish and carcasses, followed by a sharp decrease in eDNA in April 2018. Our results illustrate the utility of eDNA monitoring of management actions, the advantages of repeated sampling over time, and some challenges associated with this application of eDNA analysis.

AUTHORS: Nicholas Johnson, U.S. Geological Survey, Great Lakes Science Center; Chris Merkes, Joel Putnam – U.S. Geological Survey, Upper Midwest Environmental Sciences Center

ABSTRACT: Sea lamprey are controlled in the Great Lakes to reduce damage to valuable fisheries. Sea lamprey control is effective, but damage caused by remaining sea lamprey is poorly defined because because sea lamprey feed on blood and traditional gut content analysis has not possible.  Here, we test the concept that sea lamprey diet can be quantified by barcoding DNA in sea lamprey feces.  Specifically, we determined the percentage of fecal samples containing measureable DNA from host fishes when collected from (1) recently fed parasitic sea lamprey, (2) fasted parasitic sea lamprey transitioning to the adult stage, and (3) adult sea lamprey captured from a spawning stream.   If successful, the method could help managers better interpret lake trout wounding rates by providing insight as to how often hosts alternative to lake trout are targeted by sea lamprey. Ultimately, our vision is that adult sea lamprey assessment in each Great Lake may be able to produce an annual estimate of abundance and an estimate what fishes that cohort of adult sea lamprey were feeding on, so that fish managers could estimate damage caused to specific fish stocks.

AUTHORS: Aaron P. Maloy, Stephanie Dowell, Roman Crumpton, James Henne, Julie C. Schroeter, Christopher B. Rees, Meredith L. Bartron – U.S. Fish & Wildlife Service

ABSTRACT: Flathead catfish (Pylodictis olivaris) are large, primarily piscivorous, predators native to Gulf Coast drainages of the Mobile, Mississippi and Rio Grande River.  Intentional stockings outside of their native range were common in the early to mid-20^th century, many of which resulted in self-recruiting populations that have become invasive.  Flathead catfish alter native species communities through direct predation and are considered one of the most biologically harmful invasive fish. Obtaining detailed trophic data through traditional dietary analysis is difficult due to the lack of morphological characteristics of prey and because fish are commonly taken with empty stomachs. To address these challenges a study was undertaken on the Edisto River, South Carolina to assess the trophic ecology of invasive flathead catfish using DNA-based dietary methods. A combination of DNA barcoding and metabarcoding revealed a varied diet of crustaceans, bivalves, eggs and numerous fish species.  Traditional COI barcoding was useful for determining the identity of larger remnants of prey items of both fish and invertebrates.  Metabarcoding of the 12S rRNA gene targeted fish species and was successful at identifying prey even when morphological examination determined stomachs to be empty.  A higher rate of prey detection was observed in material collected from the stomachs than that obtained from the intestines.  Used in conjunction, the two methods provided a more complete understanding of flathead catfish predation than any one method in isolation.

AUTHORS: Christopher Schwinghamer, Quinton Phelps, Kyle Hartman – West Virginia University

ABSTRACT: Aquatic invasive species can have broad impacts on aquatic ecosystems. Through direct and indirect competition, alteration of existing habitats, and increased predation pressure, non-native species can alter the composition of native fish communities. Two non-native carps from the genus Hypophthalmichthys, Silver H. molitrix and Bighead H. nobilis carps, were introduced into the Mississippi River Basin in the 1970’s through escape from aquaculture facilities and have established populations throughout much of the basin. Due to their planktivorous diets, these non-native invaders possess a high likelihood for competition with native fishes. This creates the potential for shifts in community composition in reaches where they are present. One such reach, in which Silver and Bighead carp established in 2004, is the Middle Mississippi River. Principal response curve analyses of the fish community data was performed to evaluate shift in community composition over time using long term monitoring data. Introductions of these carps appears to have altered native fish communities. Results suggest dramatic declines in abundance of Gizzard Shad Dorosoma cepedianum, while populations of benthic omnivores such as catfish and suckers and abundant prey species may be slightly increasing post-carp establishment. Gizzard Shad, a highly abundant prey species, represent the most abundant native planktivore who likely share the largest dietary overlap and thus highest intensity of competition with the carps. While some species may be experiencing increased abundances, the magnitude of their increase in far exceeded by the declines in Gizzard Shad populations. As such, proper management of invasive carp populations is vital to maintaining healthy fish communities in the Middle Mississippi River.

AUTHORS: Jeffrey C. Jolley, Duane C. Chapman, Katelyn M. Lawson – US Geological Survey; Wyatt J. Doyle, US Fish and Wildlife Service; Kevin J. Meneau, Missouri Department of Conservation

ABSTRACT: Intensive and efficient harvest methods for invasive Asian carp in the Mississippi River Basin may alleviate negative effects of overabundance and are desired by fisheries managers.  Commercial desirability of these fish may provide economic benefits, as well.  We conducted a mass harvest at Creve Coeur Lake, Missouri using the Unified Method which was developed by Chinese fishers for harvesting carp from floodplain production lakes.  The method consists of using a variety of driving, herding, and netting techniques, in unison, to concentrate large numbers of fish from large waterbodies to a defined collection location.  We used a combination of boat electrofishing, electrified trawling, and boat-mounted acoustic deterrents to drive fish from a series of block-netted cells in the lake to concentrate fish.  Driving methods were extremely successful and 80% of the lake was mostly cleared of fish in seven days of work.  Fish behavior eventually changed when high concentrations were created and driving methods had greatly reduced effectiveness.  Fish were not successfully driven into an Iruka-style stownet likely due to a combination of water depth, physical location, and mouth opening size.  We used beach seining techniques using block nets to capture large schools of fish that had formed.  Four seine hauls resulted in 108 metric tons of Asian carp removed from the lake.  Preliminary estimates suggest that at least 50% of the Asian carp (> 40,000 fish) were harvested from the lake.  Analyses of companion environmental DNA, hyrdoacoustics, and mark-recapture data will provide additional information on efficiency of harvest. 

AUTHORS: Maurice Sadowsky, President, MJSTI Corp.

ABSTRACT: The bighead and silver carps (combined bigheaded) are an alien invasive species that escaped from aquaculture around 1980.  About 35 years later an estimated 12 to 30 million fish inhabit about 6,400 miles of the Mississippi Basin.  Every year the fish expand their territory and or their bio-mass density on the margins of their habit.The paper uses literature and Asian Carp Regional Coordinating Committee (ACRCC) and other government reports to review the programs to control these fish.  The ACRCC funds three major efforts: barriers, education/early detection/enforcement and population control.  Each division will be reviewed.The paper will then discuss the realities of controlling the bigheaded carp.

AUTHORS: Scott F Collins, Anthony Porreca, Michael Nannini, Joseph Parkos III, David Wahl – INHS

ABSTRACT: A modular electrical barrier (MEB) was developed as a tool to deter or disrupt the movement of fishes for the purposes of an adaptive approach to pest management.  The design required a non-physical barrier that would not impede boat traffic or floating debris, sufficient power to generate an electrical field at a diverse set of locations, modularity such that the MEB can be transported to logistically feasible locations, and be safely operable by fisheries professionals. The MEB system consists of generators which provide power to one or multiple 5-kW pulsers which modulate the electrical output to the electrodes (anode and cathode steel cables).  Individual pulsers can be linked to fit location dimensions (depth, width, conductivity). To test the effectiveness of the MEB, we conducted an experiment consisting of two trials in separate 0.4-ha ponds.  For each trial, we constructed a large RFID antenna (1 × 30 m) and PIT-tagged (23 × 3.85 mm HDX tags) individual fish from 8 species (4 invasive, 3 native) in order to track fish activity (total detections; average detections) in response to operation of the MEB.  When the MEB was off, ambient fish activity ranged from 500-1600 detections per day.  While the MEB was on, the number of fish detections dropped to only 7 total (6 or 0.05% of trial 1; 1 or 0.01% of trial 2), and most detections were associated with fish mortality.  After the MEB was turned off, fish detections increased after a few hours, and fish activity returned to peak numbers after 4.5 days.  Findings from this experiment indicate that the MEB can greatly deter fish movements; however, like all non-physical barriers, it may not be 100% effective at stopping fish.

AUTHORS: Maurice Sadowsky, President, MJSTI Corp.

ABSTRACT: MJSTI proved a selective, safe and low-cost fish pesticide with the goal of controlling the bighead and silver carps (bigheaded carps).  The technology and experiments will be discussed and compared to the USGS antimycin A/beeswax formulation (with patent lawyers’ approval).  The US patent should be submitted in 2018.  The formulation is selective as a digestive poison.  It is safe using FDA additives.  The average raw material cost is 1/12 to 1/30^th of MJSTI’s estimated USGS antimycin A/beeswax raw material cost.  The EPA registration should be for a new formulation since the component chemicals are all EPA registered pesticide ingredients.  The technology has application for other fish including common carp and potentially grass carp.

AUTHORS: Cory Suski, University of Illinois; Kim Fredricks, Upper Midwest Environmental Sciences Center

ABSTRACT: Carbon dioxide is a commonly occurring, natural compound that is found in aquatic environments. Recently there has been an interest in using zones of elevated carbon dioxide to act as a movement deterrent for both invasive fishes and invertebrates. Despite the promise of this tool to aid in the control of aquatic nuisance species, there are a number of questions and concerns that arise with its use, particularly related to impacts on non-target organisms and the receiving environment. The current talk will provide an overview of carbon dioxide in aquatic environments, and show how carbon dioxide can impact both invertebrates and vertebrates, ranging from physiological disturbances to ion disequilibrium to behavioral changes. The impacts of elevated carbon dioxide on the receiving environment will be discussed, along with summary of factors influencing individual variation to high CO₂. Directions for future research and unanswered questions will also be outlined. Together, this presentation will provide an overview of how elevated carbon dioxide can impact aquatic ecosystems, and how it can function as a non-physical deterrent for aquatic invasive species.

AUTHORS: Aaron Cupp, U.S. Geological Survey; David Smith, U.S. Army Corps of Engineers; Cory Suski, University of Illinois; Kim Fredricks, U.S. Geological Survey

ABSTRACT: Carbon dioxide (CO₂) is being developed as a new fisheries control chemical. Several recent studies have demonstrated that fish consistently avoid areas of elevated CO₂ when given access to other freshwater sources. Results from these studies suggest that resource managers could apply CO₂ at pinch-point or other key management locations within rivers to block upstream migration of invasive fishes (e.g. Asian carps, sea lamprey, round goby). A full-scale demonstration of this deterrent technology is being planned for 2019 at a navigational lock to better determine the costs, effectiveness, safety and overall feasibility of CO₂ as a fish deterrent method. In addition to using CO₂ as a behavioral deterrent, other recent studies have also demonstrated that CO₂ is an effective non-selective piscicide (fish toxicant). Carbon dioxide injected under-ice using various delivery methods was effective at reducing the overwinter survival of several non-native cyprinids. Further development of CO₂ as a piscicide could give managers an inexpensive, safe, and effective method to control invasive fish populations. Results from previous studies using CO₂ as a behavioral deterrent and piscicide will be discussed with specific focus on upcoming field studies aimed at transitioning CO₂ into a useful management tool.

AUTHORS: David L. Smith, Aaron Cupp, Christa Woodley, Aaron Urbanczyk – U.S. Army Engineer R&D Center

ABSTRACT: In the United States the Asian carps threaten the Great Lakes via the Illinois Waterway.  The United States Army Corps of Engineers and partners are investigating the use of carbon dioxide   based deterrence barrier.  Carbon dioxide acts as an anesthetic that leads to immobilization and death in fishes.  We have been developing carbon dioxide response rules for Bighead carp  (Hypophthalmichthys nobilis) in a laboratory.  We are applying those rules in a hydrochemodynamic numerical model representing a carbon dioxide barrier at Brandon Road Lock and Dam, a component of the Illinois Waterway.  We explore fish response to the carbon dioxide barrier using a fish movement model.  In the model we implemented rules driven by variable water velocities and carbon dioxide concentrations and produced a movement track.  We measured fish numbers that that would 1) leave the barrier in the downstream direction, 2) become immobilized, and 3) successfully pass the barrier.   The results suggest that a carbon dioxide barrier is another fish deterrence technology that has applicability in the management of invasive species.  However, additional research and development is required to better understand fish response to carbon dioxide gradients and cost of deploying an operational barrier. 

AUTHORS: Brandon J. Wu, Rene C. Reyes, Christopher L. Hart – U.S. Bureau of Reclamation; Kevin K. Kumagai, HTI-VEMCO USA, Inc.; Scott A. Porter, Michael R. Trask – U.S. Bureau of Reclamation

ABSTRACT: As an integral part of the Central Valley Project, the U.S. Department of the Interior, Bureau of Reclamation (Reclamation), Tracy Fish Collection Facility (TFCF; Byron, California) functions to salvage fish from Sacramento-San Joaquin River Delta water exported south by the C.W. “Bill” Jones Pumping Plant.  Predation by resident piscivorous fish is a contributing factor to fish loss at the TFCF and Striped Bass (Morone saxatilis) are generally considered the most prevalent piscivorous fish species within the facility.  To improve fish salvage and meet requirements mandated by the most recent National Marine Fisheries Service Biological Opinion, Reclamation is investigating the use of carbon dioxide (CO₂) as an anesthetic to remove predatory fish from the TFCF system.  The treatment of various water conveyance channels and components of the TFCF with CO₂ has demonstrated that elevated CO₂concentrations (50–350 mg/L) increase the number and size of Striped Bass in collection tanks (salvaged), suggesting that this application is feasible and effective.  In addition, acoustically tagged Striped Bass appeared to exhibit an avoidance response to elevated CO₂ concentrations.  The removal of acoustically tagged and wild Striped Bass during CO₂ treatment allowed for calculation of removal efficiency as well as estimation of Striped Bass population within the TFCF system at the time of testing.  Efforts are currently underway to estimate optimal CO₂ concentration for removal of Striped Bass based on removal efficiency and 96-hour post treatment survival.  Preliminary results suggest that the optimal CO₂ concentration for Striped Bass removal is approximately 165 mg/L.  Future efforts will focus on increasing removal efficiency in TFCF collection tanks as well as developing methods to direct piscivorous fish out of the facility to a location where there is no impact on salvageable fish.

AUTHORS: Emily K. Tucker, Cory D. Suski – University of Illinois at Urbana-Champaign

ABSTRACT: Carbon dioxide (CO₂) has been proposed as a non-physical deterrent to prevent the movement of fishes in freshwater systems. Previous studies have shown that fish of different species tend to avoid CO₂ at 50,000-75,000 µatm, but there is also wide variation between individual fish in the amount of CO₂ required to elicit avoidance. In many of these previous studies, fish were tested for CO₂ avoidance individually. Many fish species, including bigheaded carp, are frequently found in groups, and it is not known if the response of groups of fish to CO₂ exposure is consistent with the response of individuals. Therefore, the purpose of our study was to define CO₂ avoidance in fish that are part of a social group relative to when tested individually. Bluegill were first tested individually in a "shuttle box" choice assay, to define their initial avoidance threshold. All bluegill were then assigned to groups for a social network assay to determine the social personality type of each fish. Finally, each social group was tested together in the shuttle box to define the CO₂ avoidance threshold of the group. Results indicate that fish in a social group that are exposed to CO₂ will shuttle at an average of 6 times lower partial pressures of CO₂ (pCO₂) than fish tested individually, and that fish in groups had significantly less individual variation in CO₂ avoidance thresholds than fish that were not in groups. However, social personality type was not associated with shuttling behavior. Our results indicate that individual variation in CO₂ avoidance is greatly reduced when fish are in social groups. This has important implications for the use of CO₂ in fisheries management, as less CO₂ might be needed to deter groups of fish relative to deterring individuals.

AUTHORS: Jim Stoeckel, Rebecca Tucker, Hisham Abdelrahman – Auburn University; Aaron Cupps, Ann Allert, Kim Fredricks – U.S. Geological Survey; Seth Herbst, Sara Thomas – Michigan Department of Natural Resources; Brian Roth, Michigan State University

ABSTRACT: Reduction of invasive crayfish is a major challenge facing natural resource managers.  We evaluated the ability of carbon dioxide to induce red swamp crayfish (Procambarus clarkii) to leave ponds, and the ability of terrestrial shelters to facilitate collection after emergence.  We placed 100 red swamp crayfish in ~14 x 14 m experimental ponds at Auburn University, Alabama.  Tanks equipped with regulators and diffusers were used to inject CO₂ into experimental ponds whereas control ponds received no CO₂.  Silt fencing was installed around ponds such that the bottom 2 feet was folded on the ground to serve as shelter, whereas the upper foot was installed vertically on fence posts to serve as a barrier.  Carbon dioxide was elevated to =200 mg/L in experimental ponds while pH was depressed to ~5.5.  Dissolved oxygen remained > 5 mg/L.  Greater than 50% of crayfish emerged within 6 hours.  Of these, 95% remained in sheltered areas underneath the folded fencing. They did not burrow under the fencing and were easily collected.  When a small inflow of non-carbonated fresh water was provided to a pond to simulate an underwater spring, crayfish sought shelter within this small inflow area.  Only 6% exited the pond even though CO₂ quickly reached = 200 mg/L in the surrounding waters.  Results thus far show that carbon dioxide can cause a large proportion of crayfish to emerge from ponds and seek terrestrial shelter within a short time.  Small inflows of non-carbonated water from inlets or springs can provide refuges that may severely limit emergence.  However, if these refuge areas can be identified, they may facilitate removal via trapping or seining.  Results from an invaded retention-pond trial in Michigan are currently being analyzed and will also be presented.

AUTHORS: Diane Waller, USGS Upper Midwest Environmental Sciences Center; Michelle Bartsch, Upper Midwest Environmental Sciences Center; Eric Lord, Upper Midwest Environmental Sciences Center.

ABSTRACT: Tools to control dreissenid mussel (Dreissena polymorpha and D. bugensis) populations currently rely heavily on chemical molluscicides that can be both costly and have the potential to be environmentally harmful if misused. Carbon dioxide may be a more cost-effective and environmentally neutral option for controlling dreissenid mussel populations. Past studies have demonstrated that carbon dioxide is lethal to several species of invasive molluscs, including zebra mussels, Asian clams (Corbicula fluminea), and New Zealand mud snails (Potamopyrgus antipodarum). We evaluated the effects of various treatment regimens [i.e., exposure duration and pCO₂(partial pressure of carbon dioxide)] on mortality, byssal thread formation and attachment, and narcotization behavior of adult zebra mussels. Percent mortality and time to death were determined at three temperatures across a range of pCO₂ levels (70,000 – 250,000 µm). Our results indicated that elevated PCO₂ exposure induced narcotization and reduced attachment of zebra mussels within 24 h. Time to death was inversely correlated with water temperature and pCO₂ and ranged from 3 – 13 d. The potential application of carbon dioxide into an integrated pest management program for dreissenid mussels will be discussed.

AUTHORS: Michelle Bartsch, Diane Waller – US Geological Survey, Upper Midwest Environmental Sciences Center

ABSTRACT: The potential use of carbon dioxide (CO₂) as a control tool for Asian carp and dreissenid mussels has prompted investigation into the effects of elevated pCO2, under different scenarios, on native unionid mussels. We measured the lethal and sublethal responses of juvenile fat mucket (Lampsilis siliquoidea) and the federally endangered Higgins’ eye (L. higginsii) mussels to elevated pCO₂ in acute (96 h) and chronic (28 d) exposures. The lethal and sublethal responses included: survival, growth, byssal thread formation, behavior, and gene expression. In acute exposures, juvenile mussel survival was 100% after exposure to concentrations of 178 to 457 mg/L CO₂. However, burial behavior and byssal thread formation were adversely affected during CO₂ exposure. Juvenile mussels recovered after a one-week post-exposure period as >40% of fat mucket reburied and >60% had produced new byssal threads. During chronic exposures to lower CO₂ concentrations (32 to 118 mg/L), significant mortality of juveniles occurred at =60 mg/L CO₂. Sublethal effects of carbon dioxide on growth were evidenced by reduced shell growth and body condition (dry tissue weight: shell length). Expression of chitin synthase, key for shell formation, was downregulated at 28 days of exposure. The results indicate that the response of freshwater mussels to elevated pCO2 will vary with exposure pattern. Acute exposure to even extremely high pCO2 appears to be less harmful to juvenile mussels compared to extended exposure to sublethal concentrations of CO₂.

AUTHORS: Nicole R. King, University of Toledo Lake Erie Center; Madeline G. Tomczak, University of Toledo; Patrick M. Kocovsky, US Geological Survey; Christine M. Mayer, University of Toledo Lake Erie Center; Song S. Qian, University of Toledo Lake Erie Center

ABSTRACT: Invasive grass carp have been documented in the Great Lakes since 1975. Although occasional individuals have been captured, it was assumed that most were sterile escapees from stocked ponds. However, spawning was documented in the Great Lakes in 2015 with the collection of eight eggs from the Sandusky River, Ohio, a Lake Erie tributary. In 2016 no eggs were found despite extensive effort, likely because no high discharge events occurred, and grass carp, like some other non-native carps, spawn during high flows. Monitoring continued in 2017 with increased sampling effort including the addition of a second net and adaptive sampling after egg detection to follow the spatial extent of the egg mass. In 2017 the Sandusky River yielded 7,000+ eggs during two high flow events. The earliest developmental stage, three (stage one= no cell division, thirty= hatch) occurred at the most upstream site and the latest developmental stage (twenty five) near the river mouth. Egg stages were more variable at downstream sites and during lower flows; slower moving eggs are more likely to hatch in the river and survive to larvae. The pattern of egg stages and spatial distribution over time indicated spawning likely occurred several times or over a prolonged period. Although the hydrograph indicates that grass carp spawn during high flows, it is unknown what proximal cues initiate spawning and what specific conditions increase the likelihood of egg survival. We back calculated spawning time based on egg stage, collection location, and temperature to determine what specific factors may trigger spawning. Furthermore, we examined the conditions that likely support egg hatching and survival within the river. Preliminary analysis indicates several spawning bouts over a <10 hour time period. The ability to predict the timing and location of GC spawning and recruitment potential has implications for future control efforts.

AUTHORS: Hae H. Kim, Quinton E. Phelps – West Virginia University Division of Forestry and Natural Resources; David Weyers, Sara J. Tripp – Missouri Department of Conservation Big Rivers Field Station.

ABSTRACT: Survival during early life history and recruitment adult structure population demographics. Numerous studies have demonstrated that riverine fishes are prone to variable early life survival and recruitment. High abundance of Silver Carp Hypophthalmichthys molitrix in the upper Mississippi River basin suggests great spawning and recruitment success. Previous studies have largely focused on characterizing adult Silver Carp populations. However, early life history has not been evaluated. Thus, we examined relative abundance, growth rates, hatch timing, and mortality of age-0 Silver Carp. We used data collected in mini-fyke nets by the Long Term Resource Monitoring element in three river upper Mississippi River reaches. A total of 154,092 age-0 Silver Carp were captured, ranging from 7.5-170 mm. Catch per unit effort ranged from 0-107 fish/net with an overall average of 11.86 (0.4) fish/net. Growth rates ranged from 0.74 – 1.81 mm/day with a total mean growth rate of 1.25 mm/d (0.03) mm/day. Daily mortality (z) ranged from 0.74-0.94 and averaged 0.832 (0.09). Silver Carp hatched within a 115-day window between 22 May and 15 September, with hatch peaking between 21 June and 19 July. Baseline demographic knowledge will aid managers control and limit Asian Carp spread throughout the Mississippi River Basin.

AUTHORS: Rebekah L. Anderson, Nathan J. Lederman – Aquatic Nuisance Species Program, Illinois Department of Natural Resources; Cory A. Anderson, U.S. Fish and Wildlife Service; Jason A. DeBoer, Illinois River Biological Station, Illinois Natural History Survey.

ABSTRACT: Substantial research attests to the injurious impacts invasive silver carp (Hypophthalmichthys molotrix) have on Midwestern U.S. river systems. Particularly, the dietary overlap between silver carp and native planktivores has resulted in declined condition and abundance of these species in areas where silver carp dominate the community (i.e., the lower Illinois River). However, additional research demonstrates silver carp may benefit native non-planktivorous fishes because of the carp’s ability to produce young at a large scale providing an abundant prey source for native piscivores, and their nutrient rich fecal pellets may enrich benthic forage quality for native benthivores. Potential positive effects of silver carp for native fishes are not fully understood, and research is limited in natural systems. Here we determine whether silver carp benefit non-planktivorous native fishes in the lower Illinois River (i.e., Peoria, LaGrange, and Alton pools) by examining native piscivore and benthivore body condition over time utilizing two standardized long-term data programs. We found a significant positive relationship between silver carp abundance and native benthivore body condition. Moreover, visual trends indicate increased body condition during and immediately after strong silver carp year classes (2008 & 2014) for both native piscivores and benthivores. Therefore density-dependent effects may exist where juvenile silver carp populations and benthic nutrient levels must reach a threshold before they are exploitable (i.e., beneficial) resources. We suggest more years of data that incorporate strong silver carp year classes may be needed to clarify potential positive effects of silver carp for native non-planktivorous fishes.

AUTHORS: Jeremy Hammen*, U.S. Fish & Wildlife Service, Columbia Fish & Wildlife Conservation Office; Jahn Kallis, U.S. Fish & Wildlife Service, Columbia Fish & Wildlife Conservation Office; Emily Pherigo, U.S. Fish & Wildlife Service, Columbia Fish & Wildlife Conservation Office; Jason Goeckler, U.S. Fish & Wildlife Service, Columbia Fish & Wildlife Conservation Office

ABSTRACT: Effective fisheries management requires representative data that can be collected in an efficient, reasonable timeframe. This can be difficult for invasive species, like Bigheaded carp, where conventional methods can be limited in their ability to assess populations. Recent gear development and evaluation efforts have provided crucial information on the advancements in sampling methods and tools for Bigheaded carp. Information gained from these studies could be used to give managers and researchers the ability to appropriately assess these Bigheaded carp populations over a temporal and spatial scale. A pool-wide Bigheaded carp monitoring design using one of these novel gears, the electrified dozer trawl, was developed to evaluate the population characteristic differences throughout the Illinois River. Preliminary (first year) results demonstrated that population demographics at the pool level differed throughout the Illinois River. Relative abundance and size structure change throughout the Illinois River and small fish (< 200mm) were absent from the upper two pools. Additionally, it appears that habitats (main channel border, side channel, backwater) may differ in Bigheaded carp demographics but results after the first year were not significant likely due to small sample size. Estimated sample sizes based on minimizing variation in relative abundance and size structure appear to be representative through one year. Early results suggests that management of Bigheaded carp in the Illinois River may be different from pool to pool. Additionally, further refinement of the sampling efforts may be possible (i.e., smaller sample size) to make monitoring these populations more efficient and effective. Maintaining successful management activities for Bigheaded carp will require cost-effective sampling efforts in a representative and effective matter. This work will benefit those management efforts in the Illinois River and this study could provide the framework to expand throughout their Mississippi River basin where Bigheaded carp are located.