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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]

White Crappie (Pomoxis annularis) and Black Crappie (P. nigromaculatus) were studied in three southeast Kansas reservoirs to assess exploitation and determine if current regulations were conducive for sustainable populations. Trap nets were used to sample crappie in Elk City Reservoir, Big Hill Reservoir, and Parsons City Lake. Crappie measuring 210 mm and greater received Floy FD-94 tags that served as entries for rewards to encourage tag reporting. Harvest and angler demographic information were collected when tags were reported. Postcard surveys and motion-sensed cameras were used in conjunction to estimate angler effort and reporting rate on Parsons City Lake. Annual exploitation rates (i.e., percent of fish harvested) determined by tag returns and corrected for nonreporting and tag loss were 28.3%, 21.8%, and 3.9% on Elk City Reservoir, Big Hill Reservoir, and Parsons City Lake, respectively. Overfishing was not occurring, so current statewide regulations were likely appropriate, and no changes may be necessary. [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]

The loss of spawning habitat has been identified as a limiting factor to population growth for lake sturgeon, Acipenser fulvescens, the most widely distributed species of the family in North America. While local information exists about lake sturgeon spawning habitat, a synthesis of all available data is needed across its range. Our study used meta-analytical techniques to describe the mean and range of critical spawning habitat characteristics based on data from 48 sites across all major watersheds in which lake sturgeon are found. Data were compiled into univariate habitat suitability indices to describe the spawning niche. Results indicate that peak suitability occurred at depth-averaged velocities of 0.6 m x [s.sup.-1], depths of 0.55-0.85 m in small rivers (100 [m.sup.3] x [s.sup.-1]), over cobble substrates (64-256 mm), and that suitable water temperatures decreased with increasing latitude. This study provides a comprehensive review of critical spawning criteria from which future habitat suitability models can be adapted. Il a ete etabli que la disparition d'habitats de frai est un facteur qui limite la croissance des populations d'esturgeons jaunes, Acipenser fulvescens, l'espece d'esturgeons presentant la plus grande repartition en Amerique du Nord. Si de l'information locale est disponible sur l'habitat de frai de l'esturgeon jaune, une synthese de toutes les donnees disponibles est necessaire pour l'ensemble de l'aire de repartition. Notre etude fait appel a des techniques metaanalytiques pour decrire la moyenne et l'etendue de caracteristiques de l'habitat de frai essentiel a la lumiere de donnees de 48 sites couvrant tous les grands bassins versants dans lesquels l'esturgeon jaune est present. Les donnees ont ete compilees en des indices de convenabilite de l'habitat a une seule variable afin de decrire la niche de frai. Les resultats indiquent que la convenabilite maximum se trouve a des vitesses moyennes sur la hauteur d'eau de 0,6 m x [s.sup.-1], des profondeurs de 0,55-0,85 m dans les petites rivieres (debit moyen annuel 100 [m.sup.3] x [s.sup.-1]), sur des substrats de galets (64-256 mm), et que les temperatures de l'eau convenables diminuent inversement a la latitude. L'etude fournit un examen exhaustif des criteres de frai essentiels a la lumiere desquels les modeles de convenabilite de l'habitat peuvent etre adaptes. [Traduit par la Redaction], Introduction Throughout North America, habitat loss and degradation are among the most significant threats to biodiversity (Wilcove et al. 1998; Venter et al. 2006). In freshwater environments, projected extinction rates [...]

We used mark-recapture data from shovelnose sturgeon (Scaphirhynchus platorynchus) to describe range-wide growth characteristics and developed a model to estimate ages. Data were solicited throughout much of the current distribution of shovelnose sturgeon, specifically from the mainstem Missouri and Mississippi rivers and their tributaries. Shovelnose sturgeon exhibited variable growth among locations; however, adult fish exhibited almost no growth after they reached a particular size, presumably the size at sexual maturity. Shovelnose sturgeon from the Mississippi River basin attained greater maximum sizes and ages compared with the Missouri River basin. However, two populations from the Mississippi River that received high exploitation from commercial harvest had truncated age distributions with smaller asymptotic lengths. Lower Missouri River populations were characteristic of exploited populations (i.e., smaller fish and reduced longevity), presumably a result of anthropogenic effects. Wide discrepancies in maximum age and size suggest shovelnose sturgeon are capable of displaying phenotypic plasticity in response to exploitation or environmental influences. Determining metapopulation dynamics is a priority because it is unknown how population connectivity may influence dynamic rate functions and persistence of large-river fishes. Identifying potential source-sink connections in terms of population dynamics may provide a template for direction of future restoration and recovery efforts. Nous avons utilise des donnees de marquage-recapture d'esturgeons scaphirhynques (Scaphirhynchusplatorynchus) pour en decrire les caracteristiques de croissance sur l'ensemble de leur aire de repartition et elaborer un modele pour estimer les ages. Des donnees ont ete sollicitees dans la majeure partie de l'aire de repartition actuelle de l'espece, plus precisement des bras principaux de la riviere Missouri et du fleuve Mississippi et leurs affluents. Si la croissance des esturgeons scaphirhynques varie selon la localite, les poissons adultes ne presentent presque aucune croissance apres avoir atteint une taille donnee, vraisemblablement leur taille a maturite sexuelle. Les esturgeons scaphirhynques du bassin du Mississippi atteignent des tailles et des ages maximums superieurs a ceux du bassin de la riviere Missouri. Cependant, deux populations du Mississippi faisant l'objet d'une forte exploitation commerciale presentent des distributions d'ages tronquees et des longueurs asymptotiques plus faibles. Les populations du cours inferieur de la riviere Missouri sont caracteristiques des populations exploitees (c.-a-d. poissons plus petits de longevite reduite), vraisemblablement le resultat d'effets d'origine humaine. De grandes divergences sur le plan de l'age et de la taille maximums donnent a penser que les esturgeons scaphirhynques peuvent faire preuve de plasticite phenotypique en reaction a l'exploitation ou a des influences environnementales. La determination de la dynamique des metapopulations constitue une priorite puisque l'influence de la connectivite des populations sur les fonctions de taux dynamiques et la persistance des poissons de grands cours d'eau demeure inconnue. La determination d'eventuelles connexions source-puits en terme de dynamique des populations pourrait permettre d'orienter les efforts futurs de restauration et de retablissement. [Traduit par la Redaction], Introduction Determining growth is commonly assessed throughout an individual fish's life by back-calculating body length from annuli on calcified structures (e.g., scales, otoliths, fin ray or spine sections, etc.). Back-calculation [...]

Understanding linkages between natal and nursery habitats is critical for conservation of riverine fishes. Scaphirhynchus sturgeons inhabiting the middle Mississippi River may originate from the Missouri or Mississippi rivers, although relative importance of these recruitment sources is unknown. We characterized the relationship between water and sturgeon fin ray Sr:Ca, verified shifts in water Sr:Ca are recorded in age-0 sturgeon fin rays, and determined whether age-0 sturgeons from the Mississippi and Missouri rivers exhibited distinct fin ray Sr:Ca signatures. Fin ray Sr:Ca of laboratory- reared fish reflected transfer from water with elevated Sr:Ca to ambient water 1 day posthatch, indicating that short-term residency in environments can be detected. Nine of 30 age-0 fish captured in the middle Mississippi River were Missouri River emigrants. Four of these emigrants originated in the upper portion of the lower Missouri River ([greater than or equal to] 589 km upstream from its mouth), where water Sr:Ca is higher compared with the lowermost section of the Missouri River and the Mississippi River. Twenty-five of 30 fish collected from the lowermost section of the Missouri River originated within this river segment; the remainder originated upriver. Fin ray Sr:Ca enables identification of natal river segment for age-0 sturgeons and contributions of river segments to sturgeon recruitment. La conservation des poissons des riviere requiert une comprehension des liens entre les habitats de naissance et de nourricerie. Les esturgeons Scaphirhynchus qui habitent le cours moyen du Mississippi peuvent provenir de la riviere Missouri ou du Mississippi, mais l'importance relative de ces sources de recrutement est inconnue. Nous caracterisons la relation entre les rapports Sr:Ca de l'eau et des rayons de nageoires des esturgeons, verifions si les changements dans le Sr: Ca de l'eau s'inscrivent dans les rayons de nageoire des esturgeons d'age 0 et determinons si les esturgeons du Mississippi et du Missouri portent des signatures Sr:Ca distinctes dans leurs rayons de nageoires. Le Sr:Ca des rayons des nageoires de poissons eleves en laboratoire reflete le transfert de l'eau a Sr:Ca eleve a de l'eau ambiante 1 jour apres l'eclosion, ce qui indique qu'une residence de courte duree dans un environnement peut etre detectee. Neuf de 30 poissons d'age 0 captures dans le cours moyen du Mississippi etaient des immigrants provenant du Missouri. Quatre de ces immigrants venaient de la portion superieure du cours inferieur du Missouri (≥589 km de son embouchure) ou le Sr:Ca de l'eau est plus eleve que dans la section plus en aval du Missouri et dans le Mississippi. Vingt-cinq des 30 poissons recoltes dans la section la plus en aval du Missouri provenaient de ce segment de riviere; les autres venaient de l'amont. Le Sr:Ca des rayons de nageoires permet d'identifier le segment de riviere de naissance chez les esturgeons d'age 0, ainsi que les contributions des differents segments de la riviere au recrutement des esturgeons. [Traduit par la Redaction], Introduction Understanding interrelationships among habitats used by fishes for spawning, nursery, growth, and refuge is paramount for conservation efforts (Schlosser 1995; Fausch et al. 2002). Knowledge of geographic areas that [...]

ABSTRACT Knowledge of the population structure of northern pike (Esox lucius), an important recreational and top-level piscivore, is essential to Nebraska Sandhill lakes management. We collected a sample of adult [...]

Understanding spatial variation in non‐native fish species population ecology is imperative, where environmental, biotic and invasion‐related mechanisms contribute to spatial heterogeneity. Established populations of invasive silver carp Hypophthalmichthys molitrix are currently found throughout a large portion of the upper Mississippi River (UMR) basin. Despite their recent invasion and broad environmental tolerances, silver carp population ecology and linkages to environmental conditions in the UMR remain understudied. There were two objectives for this investigation: (a) to estimate correlations among population characteristics and the influence of latitude and the time since first detection, and (b) to model the influence of river discharge and temperature on growth early in life to age 3. We estimated spatial variability in silver carp population characteristics and dynamics from nine sites across the UMR and assessed if biotic, abiotic or invasion‐related (time since first detection) variables influence spatial patterns. Silver carp body weight, size structure, annual mortality, and growth parameters varied among locations. Silver carp recruitment was less stable for populations with higher relative abundance estimates and where carp were first detected ≥20 years ago whereas maximum carp age decreased with increasing latitude. Although model selection indicated silver carp length at age 3 was associated with mean daily discharge (m3/s) coefficient of variation, mean May‐June temperatures, and ordinal date of maximum discharge, parameter coefficients and effect sizes were small and not biologically meaningful. Our results suggest that silver carp populations are governed by intraspecific mechanisms, but time‐dependent changes in populations may partially underpin heterogeneity across populations. Our study helped further disentangle silver carp population ecology in the UMR by understanding carp ecology as a function of their invasion. [ABSTRACT FROM AUTHOR]