Objective We sought to estimate the amount of low-frequency electrofishing sampling effort that is required to precisely characterize the relative abundance and length distribution of seven lentic Blue Catfish Ictalurus furcatus populations.Methods We used low-frequency electrofishing (15 Hz, 30% duty cycle) to sample Blue Catfish from seven Kansas impoundments using standardized methods and randomized site selection between 2018 and 2023. A resampling approach was used to determine the precision of estimates of relative abundance (catch per effort [CPE]) and CPE of preferred-length (>= 760 mm) fish as a function of increasing sampling effort (e.g., number of 300-s sampling sites). We considered the number of sample sites to be acceptable if 80% of the resampled iterations exhibited a relative standard error of the CPE estimate <= 25%. We used a similar resampling approach to compare the length distribution of subsampled populations with those of reference populations. In these tests, we considered the estimated number of sample sites to be acceptable when 80% of the resampled iterations showed no difference from the respective population's reference length distribution using Kolmogorov-Smirnov tests.Results The sampling effort that was needed to collect precise and representative estimates varied widely by impoundment and metric. Acceptable precision of CPE values was predicted to occur with 40 to 105 sites except in one low-density population where suitable precision was not attained at 200 sites. Suitable precision of preferred-length CPE was attained in one population at 190 sites, but it could not be attained with 200 sampling sites for the other populations. We were able to collect representative length distributions by sampling between 10 and 110 sites.Conclusions Greater sampling effort (40 to 100 sites) than has been reported previously in other studies was needed to accurately estimate the Blue Catfish population metrics in Kansas impoundments. However, alternate methods are likely needed to determine the portion of the population >= 760 mm. These benchmarks and recommendations provide additional guidance for managers in tailoring effective, efficient sampling strategies to inform future Blue Catfish management plans. Blue Catfish populations require reliable monitoring for successful management. We suggest that relative abundance and length distribution can be reasonably estimated with 40-100 sampling sites.

Zebra mussels (Dreissena polymorpha) have caused significant ecosystem changes across North America since their introduction, yet their effects on fish populations remain poorly understood, particularly in Great Plains reservoirs. We quantified effects of zebra mussel invasions on water quality and fish assemblages across 25 reservoirs >5 km2 in Kansas, U.S., where invasions have occurred over the past 2 decades. Using data from invaded reservoirs before and after they were invaded, and data from uninvaded reservoirs, we evaluated changes in water quality parameters with random forest models, and we evaluated trends in long-term fish abundance data and creel data with generalized linear mixed models. Overall, we found minimal impacts of zebra mussel invasion on water quality, fish species abundance, or angler use. Random forest models estimated that zebra mussel invasions had little importance in predicting water quality, while reservoir identity was the strongest predictor. The 95% confidence intervals for abundance trends in invaded reservoirs included zero for all species except largemouth bass, which demonstrated a small, and likely not biologically meaningful, decrease following invasion. Furthermore, all fish species showed similar estimates for abundance trends in invaded and uninvaded reservoirs. Angler use also showed no response to zebra mussel presence. Although zebra mussel invasions might have other negative consequences (e.g., on water treatment facilities), our results suggest that invasions in Kansas reservoirs have not considerably affected water quality or fish populations in the past 2 decades.

Objective Blue Catfish Ictalurus furcatus have been widely stocked across the Midwestern and eastern United States, raising concerns about their potential competitive and predatory effects on other species, particularly Channel Catfish Ictalurus punctatus, which possess similar life histories and feeding strategies. We hypothesized that increasing Blue Catfish abundance in Kansas reservoirs would lead to increased overlap of dietary and space use with Channel Catfish. The purpose of this study was to quantify habitat and diet overlap of these two species.Methods We used acoustic telemetry and gastric lavage to quantify resource use and overlap of Blue Catfish and Channel Catfish in two northeastern Kansas reservoirs during 2023 and 2024. We used generalized linear models and multivariate ordination techniques to analyze the data.Results Our analysis revealed that Blue Catfish lived farther from shore and occupied deeper water (x & strns; = 6.84 +/- 4.35 m) than Channel Catfish (x & strns; = 5.09 +/- 3.27 m). Although both species exhibited similar movement patterns and diverse diets, we found that Channel Catfish fed more frequently on crayfish and terrestrial macroinvertebrates than Blue Catfish. Variables relating to season and reservoir strongly influenced the diets of both species.Conclusions Our results demonstrate that co-occurring populations of Blue Catfish and Channel Catfish use a wide variety of habitat and dietary resources, yet they also have distinct niches that might mitigate the intensity of competitive interactions. Continued monitoring of these populations is crucial for evaluating population trends and competitive interactions. This will allow for informed management plans to prevent negative effects on both species' populations and abundance of other species. Blue Catfish is a popular sport fish that is stocked in many areas outside their native range, leading to concerns about resource overlap with other fish, especially the native Channel Catfish. We used acoustic telemetry to track both species and analyzed their stomach contents in two Kansas reservoirs to see how they used habitat and what they ate. Our findings suggest that when Blue Catfish are abundant, Channel Catfish may change where they live and what they eat to avoid exploitative competition. This research can help fisheries managers make decisions to ensure healthy fish populations for anglers.

Objective: We sought to quantify Largemouth Bass Micropterus nigricans diets in small impoundments and investigate how seasonal and ontogenetic factors interact across a gradient of Gizzard Shad Dorosoma cepedianum relative abundances to influence prey selection. Methods: We collected stomach contents from 3,500 Largemouth Bass across 12 small Kansas impoundments (<166 ha) during June, August, and October 2017 through 2020. We used generalized linear mixed-effects models to quantify the influence of Largemouth Bass size, season, and Gizzard Shad relative abundance on the frequency of coarse-scale (fish, crayfish, aquatic insects, and zooplankton) and fine-scale (Centrarchidae, Gizzard Shad) prey taxa in Largemouth Bass diets. Results: Gizzard Shad relative abundance significantly altered diet composition in addition to notable effects of season and Largemouth Bass size. Increasing Gizzard Shad abundance was associated with reduced consumption of alternative littoral prey (Lepomis spp. and crayfish) and increased aquatic insect consumption, particularly in individuals <150 mm. While consumption of Gizzard Shad increased with Gizzard Shad abundance, its occurrence in diets remained low (<10%) and was seasonally restricted to October. Conversely, consumption of Centrarchidae declined significantly as Gizzard Shad abundance increased. Conclusion: Despite their low occurrence in diets, Gizzard Shad appeared to alter food-web structure by disrupting consistent littoral energy pathways and diverting resources into a dynamic pelagic base that was largely unavailable to Largemouth Bass. The negative association between Gizzard Shad abundance and Centrarchid consumption suggests that small impoundments with high densities of Gizzard Shad may exhibit reduced trophic efficiency, as energy is sequestered in gape-protected Gizzard Shad biomass rather than being transferred to Largemouth Bass. Further research integrating growth and bioenergetic data is warranted to determine how energy is most successfully transferred to Largemouth Bass, specifically comparing net benefits of a transient autumn pulse of Gizzard Shad compared with a consistent supply of littoral forage.

Objective Bluegill Lepomis macrochirus support recreational fisheries throughout much of their geographic distribution. One characteristic of the species is for males to exhibit alternative reproductive tactics to maximize production of progeny. These divergent strategies coupled with size-selective harvest by anglers create the potential for fisheries-induced evolution (FIE). As such, we sought to characterize genetic diversity of five fished and five unfished Bluegill populations to test for the occurrence of FIE.Methods Fin clips from 100 Bluegill across 10 populations in southeast Kansas were collected to examine genetic diversity and test for the occurrence of FIE associated with long-term selective harvest. Individuals were genotyped using genome-wide single-nucleotide polymorphism data via restriction site-associated DNA sequencing. Population genetic analyses were performed on three data sets: all individuals, females only, and males only.Results Genomic analyses from 92 Bluegill across the 10 populations demonstrated consistent observed heterozygosity across populations that was less than expected heterozygosity. As such, there was low genetic differentiation among populations, with over 94% of genetic difference explained by individuals within populations and no evidence of selection. Cluster analysis supported these findings of genetic overlap among populations by grouping individuals into one to three distinct genetic populations.Conclusions We found no evidence of FIE in either fished or unfished Bluegill populations. Rather, there was little genetic variation among the study populations except for one population. Combining controlled experiments with recent advances in describing the Bluegill genome would be useful for identifying the presence or absence of FIE in exploited Bluegill populations. Bluegill populations vulnerable to size-selective harvest over several decades showed limited genetic difference from nearby, yet spatially distinct, unfished populations. Further, no genetic evidence of fisheries-induced evolution was observed.

Objective Understanding the "who, what, when, where, and why" of angler harvest is a critical component of managing fisheries with harvest-based regulations. Previous research has suggested that these are complex questions deserving further examination at broader spatiotemporal scales. Here, we use a long-term creel survey data set to develop models for predicting likelihood of fish harvest using a suite of explanatory variables.Methods We used creel survey data to summarize 831,479 records of fish angled from Kansas waters between 1997 and 2024 (excluding 2020 and 2021) to develop models for predicting likelihood of angler harvest. Our approach included the development of a global binary classification model using a training data set (70% of records) that included harvest or release as the response variable and a suite of 20 explanatory variables, including fish species or taxa. The model was then applied to a testing data set (30% of records) to measure accuracy. This process was repeated for the 12 most occurring species/taxa in the creel database with all explanatory variables, excluding species/taxa. Variable importance from the global model and summarized variable importance from the species/taxa model were used to quantify factors associated with an angler's decision to harvest a captured fish.Results The global classification model included 13 of 20 predictor variables for node split determinations, although only combinations of legal harvest status, fish length, and species/taxa were included in the final model. When applied to testing data, we observed accurate classification in 84.3% of records. Species/taxa models displayed considerable variability in included variables. Among the 12 models, 18 of 19 variables were included in node split determinations by the classification algorithms. Model accuracy varied from 67.6% for sunfishes Lepomis spp. to 96.4% for Smallmouth Bass Micropterus dolomieu. Summarized variable importance across all species/taxa models identified fish length and legal harvest status as the most consequential variables influencing fate of captured fish.Conclusions Legal harvest status, fish length, and species/taxa were important determinants of the likelihood of fish harvest in our study. However, some species/taxa (e.g., black basses Micropterus spp.) were infrequently harvested regardless of other associated variables. The interplay between examined factors highlights the importance of understanding social norms associated with fisheries and potential limitations of widespread harvest-based regulations. Anglers primarily decide to harvest or release fish based on species, length, and whether it is legally harvestable. However, sometimes there are informal rules or expectations (i.e., social norms) that may dictate anglers' decision to keep or release a captured fish.

Debate about the potential benefits and risks of live sonar technology (also known as live imaging sonar and forward-facing sonar) in freshwater recreational fisheries includes growing discussions regarding regulation. Synthesizing sparse literature, experiences of the coauthors, and observations from traditional and social media, we revealed a varied range of potential outcomes for fisheries when this technology is used. Of particular concern is the ability to find fish that were previously cryptic and to target them in ways that increase capture efficiency (e.g., through snagging where legal or more accurately presenting lures or baits); thus, increasing catchability. Conflicting views within the recreational fishing community about the “fair chase” aspect of this technology have prompted discussions regarding regulations. We anticipate continued debate around this topic and hope that this paper will inspire more empirical research (ecological and human dimensions) to provide resource managers and the recreational fishing community with insights and guidance on how to ensure that live sonar is used in ways that benefit fisheries management and stakeholder interests.

Abundant gizzard shad Dorosoma cepedianum (Lesueur, 1818) are thought to contribute to phytoplankton blooms by translocating nutrients from sediments to the water column where they can be readily taken up by phytoplankton and by consuming herbivorous zooplankton that might control phytoplankton. To assess the influence of gizzard shad relative abundance on lentic ecosystems, we sampled 12 small impoundments located in the Great Plains, USA over 4 years. We used linear mixed models to test for associations with limnological characteristics, including total nitrogen (TN) and total phosphorus (TP), zooplankton densities, and phytoplankton abundances. Gizzard shad relative abundance was associated with elevated TN and TP and a general reduction in zooplankton densities. There was substantial within-lake temporal variation in gizzard shad abundance across sampling months, with a negative association between TP and gizzard shad abundance in June but a positive association in August. We did not provide evidence that gizzard shad relative abundance was associated with cyanobacterial abundance or total phytoplankton abundance. The lack of a relationship between these factors might have been obscured by the discontinuous polymictic mixing regimes of the study impoundments, the rapid turnover of phytoplankton, and other drivers, such as variable nutrient runoff across our study impoundments.

In Kansas, crappie Pomoxis spp. (White Crappie P. annularis, Black Crappie P. nigromaculatus) fisheries have important social and economic value, making management of these species a high priority. However, management of crappie fisheries is often challenging due to a paucity of information regarding the specific dynamics regulating populations. Even when population dynamics information is available, the relative influence of exogenous factors on crappie populations is poorly understood. To improve the management of crappie fisheries, we sought to: 1) describe White Crappie population dynamic rates throughout Kansas and 2) assess the influence of exogenous factors (i.e. system characteristics and biotic interactions) on the dynamics of White Crappie populations. Annual survey data and associated age data were used to estimate relative abundance, recruitment, individual growth rates, and total annual mortality rates of each White Crappie population. The relationships between system characteristics, fish abundance variables, and White Crappie population dynamics were assessed using principal component analysis and multiple linear regression. In total, 19,874 White Crappie were sampled from 32 impoundments and age was estimated for 3,851 individuals. In general, White Crappie population dynamics were related to a variety of abiotic and biotic characteristics that largely reflected the influence of density-dependent processes. Surface area served as a surrogate for many of the covariates considered and may be useful in guiding management of White Crappie populations. Specifically, large impoundments with high predator abundance will likely support robust crappie fisheries due to density-related improvements in growth. Conversely, impoundments with small surface areas tended to have high densities of crappies and other centrarchid competitors, which resulted in slow growth rates and potentially poor-quality crappie fisheries. Overall, our results highlight the value of dynamics rate functions for understanding the mechanisms underlying White Crappie populations which can be used to improve management of the species.

Invasive carp populations have purported a negative influence on native biota at high densities. These invasive fishes (i.e., bighead carp Hypophthalmichthys nobilis, silver carp Hypophthalmichthys molitrix, grass carp Ctenopharyngodon idella, and black carp Mylopharyngodon piceus) each exhibit similar life history characteristics. In the Neosho River-Grand Lake system (i.e., John Redmond Reservoir, Kansas, downstream to Grand Lake O' the Cherokees, Oklahoma), only bighead carp and grass carp have been documented to date. The distribution and status of bighead carp throughout this system were previously unknown due to limited historical data and low abundance. While few bighead carp are encountered within this system, grass carp exhibited relatively higher abundance a were used to provide insights into bighead carp. Captures of both species were used to inform management and suppression efforts. Sampling locations (n = 18) were established for environmental DNA analyses throughout the Neosho River-Grand Lake system. We sampled 13 sites using a suite of gears for standardized targeted fish sampling. All invasive carp were measured, sexed, and otoliths removed for ageing and microchemical analysis. Grass carp were processed for ploidy testing following the U.S. Fish and Wildlife Service protocol. Environmental DNA analyses generated positive results for the eDNA presence of bighead carp and silver carp. Otolith age estimates suggest fish are long lived and supported by multiple year classes. Additionally, a sampled two-year-old grass carp demonstrates spawning and recruitment potential. Otolith microchemistry suggests largescale broad movement patterns. Ploidy testing confirmed the first documented evidence of diploid grass carp in the Neosho River-Grand Lake system and revealed reproductive viability. Our results may provide future insights into locations for containment, removal, and/or eradication.

ObjectiveBlue Catfish Ictalurus furcatus populations introduced into Kansas reservoirs in the past few decades have supported fisheries during the 21st century that have rapidly gained popularity among anglers. The increased importance of these fisheries has prompted questions about the status of populations, resilience to overfishing, and appropriate harvest management strategies. The primary objectives of this study were to quantify the dynamics of four Blue Catfish populations in Kansas impoundments, identify susceptibility to angler catch and harvest, and evaluate modeled population responses to harvest regulation.MethodsWe coupled capture-recapture efforts and a randomized sample design using low-frequency electrofishing to estimate population characteristics of the four Blue Catfish populations. We also estimated age and growth parameters from each population to characterize dynamic rate functions. Angler tag return data were summarized over a period of 1 year from each fishery to evaluate Blue Catfish susceptibility to angler catch and harvest. Finally, we consolidated these data into harvest regulation models to estimate the population response under varied harvest regimes.ResultEstimated densities of stock-length (>= 300 mm total length) Blue Catfish varied from 2.79 to 20.14 individuals/ha. Growth was variable, with individuals expected to reach quality length (>= 510 mm total length) as early as age 4 and as late as age 9. The largest fish in each population were more vulnerable to angler capture, although harvest was low for all sizes of fish. Harvest regulation models indicated that populations were resilient to increased exploitation under all scenarios, with a limited risk of growth overfishing or recruitment overfishing.ConclusionBlue Catfish populations in Kansas reservoirs exhibit different dynamics but demonstrate resilience to overfishing. The largest individuals in populations are much more vulnerable to angler catch than smaller fish, but the risk of overharvest appears mitigated by angler self-regulation.

Lapillus otoliths and several preparations of pectoral fin spines have been used to age Blue Catfish Ictalurus furcatus; however, there are limited studies examining relative precision of age estimates. Further, comparisons of population characteristics (e.g., growth, mortality) resulting from age structure evaluations are needed to help fisheries managers balance resources needed to conduct investigations with quality of subsequent data. We examined sectioned Blue Catfish lapillus otoliths and sectioned pectoral spine articulating processes, basal recesses, and articulating surfaces to compare relative precision of age estimates. Additionally, dynamic rate functions and resulting population models were examined to determine if variation in age estimates resulted in divergent interpretation of population characteristics. Generally, aging precision was greatest for articulating surface and lapillus otolith sections. Although growth models generated from each aging structured differed, mortality estimates and conclusions drawn from harvest-regulated population modeling were similar across structures. These results demonstrate that although there is variability in precision and growth modeling among different Blue Catfish aging structures, estimates for key population parameters remain consistent.

A primary challenge of Flathead Catfish Pylodictis olivaris management is uncertainty associated with sampling strategies and resulting ambiguity in population-level information. Assessment of impoundment and environmental conditions that affect detection probability may aid in reducing sample variance and benefit inferences regarding changes to Flathead Catfish populations. We sampled eight small impoundments in Kansas (37-114 surface ha) using low-frequency electrofishing in summer, 2021. We revisited sites nine times over three months using an occupancy modeling framework to estimate the influence of impoundment and environmental conditions on detection probability of Flathead Catfish. We employed an information theoretic approach and ranked models built with impoundment as a random effect and three environmental variables predicted to influence detection of Flathead Catfish in small impoundments. Detection probability across all populations was 0.526 (SE 5 0.020) and was influenced by water temperature, mean depth of the impoundment, and proportion of impoundment sampled. Generally, detection probability increased with all measured variables. The inclusion of detection probability in assessments of Flathead Catfish in small impoundments can inform interpretation of catch-related metrics. Further, variable detection suggests collection of multiple samples during a defined sampling period might be more suitable for characterizing populations than a single sample.

Barrier presence in river systems has been demonstrated to impair fish assemblages. Low head dams specifically are frequently occurring barriers in riverine environments. Well-supported impacts of these structures on fishes include diminished movement, reproduction, and habitat availability. Longitudinal patterns in riverine fish assemblages have long been researched to ascertain dynamics and display interactions. The need for research becomes more critical when factoring in impacts of barriers and detrimental invasive species. Knowledge of fish assemblages can inform fisheries biologists and aid in improved management practices for recreational and ecologically important species, as well as invasive species. The Neosho River system in Kansas has 14 barriers present. Little fisheries sampling has been done in the Kansas portion of this river system from the John Redmond Dam to the Oklahoma border; therefore, sampling was conducted to inform questions posed about the fish assemblages. We sought to document the fish assemblages of the system in Kansas and examine for assemblage composition distinctions by geographic region along a longitudinal gradient. The fish assemblage dataset from this research generated a wealth of knowledge on sportfish infiltration from reservoirs, imperiled fishes, and apparent impacts from low-head dams. Information from this study will aid in future management and direct new research investigating imperiled fishes.