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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]