AUTHORS: Heidi M. Rantala, MN Department of Natural Resources, Fisheries Research; Nick Peterson, MN Department of Natural Resources, Lake Superior Fisheries; David R. Burge, St. Croix Watershed Research Station, Science Museum of Minnesota
ABSTRACT: Minnesota tributaries to Lake Superior are unique systems with glacial relict fish communities, including Brook Trout (BKT). Fish habitat in these streams is vulnerable to change, given the sensitivity of the systems. With limited groundwater inputs, hydrology is driven by precipitation and snow melt, and the streams lack buffering capacity to warming temperatures. Stream conditions are favorable to the mat-forming diatom, Didymosphenia geminata, which was detected in multiple of the northern-most streams along the Minnesota shoreline since 2018. Here, we present analyses of diets from BKT, naturalized Rainbow Trout, and several other fish species in four North Shore streams from three seasons in 2023. Fish diets were sampled from resident and migratory individuals, both young-of-year and older fish, from above (BKT only) and below natural barriers between Lake Superior and upland waters. Additionally, two of the four streams had prolific, localized Didymosphenia mats during the sampling period. As expected, we observed spatial and temporal variability in the both the diet items and amount of prey through the sampling season, as well along a stream reach. These data provide baseline information for managers to increase understanding of the ecology and status of these populations in Minnesota waters.
AUTHORS: April Simmons, MI Department of Natural Resources; Jeffrey Jolley, PhD, MI Department of Natural Resources; Christopher Vandergoot, PhD, Great Lakes Acoustic Telemetry Observation System
ABSTRACT: Angler reports have indicated a recent increase in lake-run Brown Trout (Salmo trutta) catches in Saginaw Bay, Lake Huron. This observation has garnered interest because Lake Huron stocking efforts ended in 2011 due to poor recruitment, but stocking has been maintained in some upstream tributary reaches. Genetic analysis of lake-run fish suggest fish observed in Saginaw Bay likely originated from ongoing stockings in the Rifle River. We will present the May 2024 pilot study phase results of an acoustic telemetry study scheduled to begin in spring 2025. The study aims to identify the source, strain, and migration patterns of lake-run Brown Trout, as well as assess their growth. This research may provide insights into future Brown Trout management strategies in the Great Lakes to benefit both river and lake anglers.
AUTHORS: Dylan K. Undlin, UW-Stevens Point; Justin A. VanDeHey, UW-Stevens Point; Joshua K. Raabe, UW-Stevens Point; Nick R. Peterson, Minnesota Department of Natural Resources
ABSTRACT: Salmonids represent an ecologically, culturally, and economically important fishery in Lake Superior and its tributaries. However, current fluvial conditions and climate projections forecast significant reductions in cold-water habitats in these systems. Salmonids such as native Brook Trout Salvelinus fontinalis, and non-native Steelhead Oncorhynchus mykiss depend on these volatile tributaries for at least a portion of their life. Therefore, our research aims to 1) identify critical habitat (i.e. thermal refugia) for resident and migratory Salmonids across two watersheds, and 2) determine if movements of Salmonids are related to water temperature, dissolved oxygen, and discharge. Salmonid movement was investigated in the Knife and Stewart River watersheds using 16 stationary Passive Integrated Transponder (PIT) arrays and active radio telemetry techniques. Data loggers measuring water temperature, dissolved oxygen, and discharge were dispersed across watersheds, and stratified among sub watersheds and natural habitat breaks. To date, we have PIT tagged 1100 wild Salmonids and implanted 15 radio transmitters. Preliminary results suggest Salmonids sought headwater tributaries with groundwater influence and overhead cover during periods of warmer air temperatures. Salmonids used precipitation events and cold fronts as windows for movements during times of low flows and relatively warmer water. Water temperature profiles in the lower reaches of the Knife River periodically surpassed the lethal threshold for Brook Trout, indicating an ephemeral thermal barrier between tributary headwaters and Lake Superior. More data are currently being collected to further assess movement and habitat use in these riverscapes to inform management and restoration efforts.
AUTHORS: Alexandria Keiler-Klein, University of Nebraska at Kearney; Melissa Wuellner, University of Nebraska at Kearney; Keith Koupal, Nebraska Game and Parks Commission and University of Nebraska at Kearney
ABSTRACT: Nuisance and invasive species can, directly and indirectly, affect sport fisheries, but few agencies target these fishes in annual standard surveys. Understanding when and how to sample nuisance and invasive species is important to understanding their abundance and size structures. Determining optimal assessment techniques can provide management insight into interventions to address the impacts of nuisance and invasive fish abundance on salmonid species. The objective of this study was to determine which gear and time of year could be used to assess populations of invasive (Common Carp Cyprinus carpio) and/or nuisance (White sucker Catostomus commersonii) species in one Nebraska reservoir. Experimental gill nets, modified fyke nets, and nighttime boat electrofishing were employed at nine locations across Lake Ogallala monthly from April through September 2023. All individuals of the two species were enumerated and measured for total length (mm). This information was used to calculate catch per unit effort (CPUE), the coefficient of variation around CPUE, and a measure of length variability (Shannon-Weiner diversity based on 10-mm length bins) for each gear, month, and species. Additionally, we calculated the measurement of operational effort. Measurements were ranked across gears for each month and summed. The smallest ranks were used to identify the best gear and month for sampling each species. Preliminary results indicate electrofishing captures the best length diversity and operational effort for Common Carp and White Sucker in June and May respectively. CPUE for White Suckers and Common Carp was highest in April and July fyke netting respectively. Lastly, variability in CPUE was lowest with Common Carp July electrofishing and White Suckers May gill netting. The results from this study can be used by other states and provinces addressing similar and other nuisance and invasive species assessments to allow for more proactive, rather than reactive, management interventions to support salmonid fisheries.
ABSTRACT: Pactola Reservoir in the Black Hills of South Dakota has historically been managed as a coldwater fishery for Rainbow Trout Oncorhynchus mykiss and Lake Trout Salvelinus namaycush. In 2003, Northern Pike Esox lucius were first sampled in fisheries surveys by South Dakota Game, Fish, and Parks (SD GFP) and have since become an established predator. Due to concerns of direct predation on stocked catchable (275 mm) Rainbow Trout, SD GFP partnered with South Dakota State University on a research project which evaluated Northern Pike diets and isotopes. The results of that study showed that fish smaller than 600 mm had δC13 isotope values similar to centrarchid prey species, whereas δC13 values for 600 mm and larger fish were similar to stocked Rainbow Trout. In response to this research and to reduce predation by Northern Pike, SD GFP increased the Rainbow Trout stocking size in Pactola Reservoir from 275 mm to 381 mm. The objective of this study was to evaluate Northern Pike isotope changes in response to the increased Rainbow Trout stocking size. Northern Pike (n=42) were captured in May 2021 with sizes ranging from 457 mm to 1,021 mm. δC13 values in Northern Pike smaller than 700 mm were similar to the centrarchid values seen in the previous study, suggesting that stocked Rainbow Trout had not become a major diet item for 700 mm and smaller individuals. This data was supported by an analysis of variance (ANOVA) among 100 mm size bins which revealed that significant differences in δC13 were detected between the 700 mm and 800 mm size bins, but not among 700 mm and smaller size bins. Furthermore, a piecewise linear regression technique in program R revealed a breakpoint value of 716 mm. These results indicate that the length at which Northern Pike prey upon stocked Rainbow Trout has increased by over 100 mm following the increase in trout stocking length.
AUTHORS: Natalie Coash, Missouri Cooperative Fish and Wildlife Research Unit; Ashley Hrdina, Missouri Cooperative Fish and Wildlife Research Unit; Craig Paukert, US Geological Survey, Missouri Cooperative Fish and Wildlife Research Unit; Emily Tracey-Smith, Missouri Department of Conservation; Jason Persinger, Missouri Department of Conservation
ABSTRACT: Missouri’s cold and cool water stream systems face ecological challenges due to historical alterations, land use, and chronic climate pressures. Effective management of these systems requires an applied science-based approach that considers fundamental processes such as thermal regimes, flow variability, and knowledge of surrounding land use, all of which influence aquatic habitat and biotic distribution. Water temperature, in particular, plays a critical role in shaping fish assemblages and stream biota, affecting physiology, behavior, reproduction, and overall habitat suitability. Current data limitations, including a lack of comprehensive water temperature data and insufficient aquatic community data, hinder our ability to characterize and conserve cold and cool water stream habitats effectively in Missouri. This study aims to address data gaps by estimating the distribution and extent of significant cold water stream habitats in Missouri by characterizing fish, macroinvertebrate, and macrophyte communities within these habitats and their thermal transition zones, while complementing sampling with continuous seasonal temperature monitoring and eDNA analysis. Through field sampling and analysis of existing spatial data, this research will refine our understanding of cold, cool, and warm water stream systems statewide. While this study can be useful in identifying thermal refugia and the extent of trout habitat in Missouri; the outcomes of this study will directly benefit stream resource management and conservation by providing critical data pertaining to the unique cold and cool water biological communities beyond our current policy criteria and classification of waters “that support a naturally reproducing or stocked trout fishery”. This improved characterization will support the Missouri Department of Conservation in guiding the development of habitat criteria relevant to resource management, influencing thermal designations under Missouri’s Water Quality Standards, and protecting species of conservation concern. Join us to review the project’s impetus, objectives, site selection, field methods, next steps, and key deliverables.
AUTHORS: Doug Dieterman, Minnesota Department of Natural Resources; Brian Beyerl, Minnesota Department of Natural Resources; Shawn Haase, Minnesota Department of Natural Resources; John Hoxmeier, Minnesota Department of Natural Resources; Loren Miller, Minnesota Department of Natural Resources; Jason Roloff, Minnesota Department of Natural Resources; Vaughn Snook, Minnesota Department of Natural Resources; Dan Spence, Minnesota Department of Natural Resources; Melissa Wagner, Minnesota Department of Natural Resources
ABSTRACT: Brook Trout Salvelinus fontinalis, were the only salmonid native to the cold-water streams of southeast Minnesota but were presumed extirpated following European settlement and subsequent stream degradation. Research beginning in the mid-2000s identified genetic structure patterns that deviated from known stocking histories but consistent with expected geography of native populations, leading to the identification of a presumed native “Heritage” Brook Trout strain. Distribution of this Heritage strain was limited to three stream drainages. In an effort to better manage and expand the distribution of Heritage Brook Trout; managers, culturists and researchers have since implemented several novel approaches including removal of non-native Brown Trout; collection, propagation and stocking of wild Heritage Brook Trout; and implemented new studies to compare performance of Heritage and feral Brook Trout strains in streams. This talk will provide an overview and highlight the current status of these efforts as well as, the many challenges that have arisen.
AUTHORS: Michael Siepker, Iowa DNR; Caleb Schnitzler, Iowa DNR; Dan Kirby, Iowa DNR
ABSTRACT: Although Brook Trout were likely native to Northeast Iowa, early degradation of streams led to widespread extirpations along with regulations and stocking to restore and maintain populations. Brook Trout were a common part of early fish stockings, but disappeared from Iowa stocking records by 1956. Brook Trout remained largely absent from the trout program until 1993 when fingerling and catchable Brook Trout stockings resumed. The ancestry of Brook Trout used for early stockings is generally unknown; however, Brook Trout used for fingerling and catchable trout production that began in 1993 were acquired as eggs from the St. Croix Falls fish hatchery in Wisconsin. The first genetic evaluation of Iowa Brook Trout suggested the South Pine population was a unique population, but with low genetic diversity. As a result, South Pine fingerlings were used to restore Iowa Brook Trout fisheries beginning in the mid-1990s. Today, restoration stockings are conducted throughout northeast Iowa to expand wild Brook Trout populations.
ABSTRACT: Wild trout have played an increasingly important role in trout management in Iowa over the last 20 years. Recent increases in self-sustaining trout populations has expanded and diversified opportunities for Iowa anglers to pursue trout. One of the major factors in this increase is the use of fingerling stocks derived from wild and local parents to establish wild trout populations in other streams. Such stockings have been so successful in expanding self-sustaining populations of Brown Trout in northeast (NE) Iowa that their full extent is currently unknown. Wild Brook Trout populations have also been successfully restored to several NE Iowa streams by stocking fingerling Brook Trout of South Pine Creek origin. Brook Trout is the only trout species believed to be native to NE Iowa’s coldwater streams, and fisheries managers in Iowa are interested in expanding these restoration efforts as well as protecting existing populations of the species. The purpose of this project is to assess the current distribution of Brook Trout and Brown Trout in northeast Iowa, and collect information needed to identify coldwater streams in northeast Iowa which have conditions necessary for successful restoration of wild Brook Trout populations. To efficiently target our sampling to only those stream reaches where thermal regimes are likely to be conducive to trout habitation, we are using methods developed in a recent study that used visually interpreted very high resolution (VHR) winter satellite imagery to identify coldwater stream reaches. Results of targeted sampling efforts in the Upper Iowa River watershed will be presented, and utility of using VHR winter satellite imagery to identify coldwater stream reaches will be discussed. In addition to informing wild trout management in NE Iowa, information gained from this project will also be used in an effort to update Iowa’s coldwater stream classifications.
AUTHORS: Caleb C. Schnitzler, Iowa Department of Natural Resources; Decorah Fisheries Management Office
ABSTRACT: Abstract: Brook Trout Salvelinus fontinalis are the only native salmonid to Iowa, and substantial effort has been directed toward protecting those populations. Culture of the Brook Trout from South Pine Creek, the only wild population in Iowa, began in 1996 and continued annually to restore additional populations. A more recent genetic evaluations confirmed that the South Pine Creek strain was unique and suitable for use as a brood source. The evaluations also identified five streams that had non-native Brook Trout ancestries. Of these, one population of domestic hatchery Brook Trout was identified and selected to be removed using electrofishing. Naturalized Brown Trout Salmo trutta are another threat to wild Iowa Brook Trout, with populations established in most quality coldwater streams. Two streams with barriers to prevent Brown Trout recolonization were selected for Brown Trout removal. The effectiveness of trout removal via stream electrofishing is reviewed and the use of fish culture to improve native Brook Trout restoration efforts is also discussed.
