Population Characteristics of Co-Managed White Bass and Hybrid Striped Bass in Lake McConaughy, Nebraska

White Bass (Morone chrysops) and Hybrid Striped Bass (M. saxatillis × M. chrysops) populations often coexist in the same waterbody and are known to achieve different lengths, have differing reproductive success, and provide different opportunities for anglers. However, comparative population dynamics from systems where Moronids are managed with the same regulation is often lacking. This study aimed to assess the recruitment, mortality, and growth of these species from seasonal samples collected at Lake McConaughy in 2015 and fall 2016. White Bass demonstrated highly variable recruitment in Lake McConaughy despite stocking efforts (mean recruitment variability index = 0.157). Hybrid Striped Bass year class strength was also variable, but RVI was not calculated as the number of missing year classes exceed the number of present year classes. Total annual mortality estimates for Hybrid Striped Bass (39.7%) and White Bass (41.4%) were consistent with values reported in other populations, but both species were observed to achieve uncommon longevity. Both species exhibited sexual size dimorphism, and growth was moderate and consistent with average values presented for North American populations. This study provides insight into the population dynamics of two species with trophy potential managed by the same regulation in Lake McConaughy. Differences in growth patterns indicate the current regulation affects each species differently, and managers may be able to utilize this to inform decisions about management of coexisting Moronid populations

Food habits of imperiled Plains Topminnow and diet overlap with invasive Western Mosquitofish in the Central Great Plains

Plains Topminnow (Fundulus sciadicus) populations have experienced large declines throughout the Central Great Plains, with Western Mosquitofish (Gambusia affinis) introductions suggested as a contributing factor. There are limited studies identifying the food habits of Plains Topminnow and the trophic interactions with Western Mosquitofish. This study sought to determine if a diet overlap exists between the Plains Topminnow and the introduced Western Mosquitofish by identifying the feeding habits of both species. We analyzed diets from lentic and lotic populations of Plains Topminnow captured in August and found lentic topminnows employed a generalist diet while lotic topminnow selected for gastropods. Additionally, Western Mosquitofish diets from regionally proximate lotic and lentic populations also displayed a generalist diet consisting of benthic, littoral and terrestrial macroinvertebrates. The two species did not show overlapping diets based on Schoener’s Index. Therefore we suggest the introduced Western Mosquitofish do not likely impact Plains Topminnow populations through food resource competition

Assessment of Smallmouth Bass Growth and Mortality in Nebraska Waters

Smallmouth bass (Micropterus dolomieu) have been introduced across Nebraska into a variety of waterbodies. However, an estimate of smallmouth bass growth and mortality in Nebraska waters has not been produced. The objectives of this study were to use historic sampling data to describe the growth of smallmouth bass in Nebraska lakes in relation to other regional models, growth among waterbody types (reservoirs, Interstate 80 [I-80] lakes, and rivers), estimates of age at quality, preferred, and memorable lengths, and mortality for Nebraska smallmouth bass populations. Mean length ± SE of Nebraska smallmouth bass at age 7 was 383 ± 21 mm, which is similar to national and regional values. Mean lengths at age of smallmouth bass in I-80 lakes and reservoirs were similar, but lengths were larger in rivers than in I-80 lakes and reservoirs at ages 3–5. Mean total annual mortality measured 0.41 (± 0.06 SE). These growth and mortality rates allow biologists to set appropriate management objectives and assess local sampling results with proper perspectives

Whooping Crane (Grus americana) family consumes a diversity of aquatic vertebrates during fall migration stopover at the Platte River, Nebraska

The Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) migrates approximately 4000 km through the central Great Plains biannually, between their breeding and wintering grounds. Whooping Cranes depend on stopover sites to provide secure resting locations and the caloric resources necessary to complete their migration, such as the USFWS-designated critical habitat area in the Central Platte River Valley (CPRV) of Nebraska. This area includes braided river habitat characterized by low-elevation and submerged sandbars, which provide important roosting and foraging opportunities for migrating Whooping Cranes. We used long-range photography, videography, and behavioral scan sampling to document forage items consumed by Whooping Cranes during an 11-day stopover in this area during the fall of 2019. We identified 3 adult-plumage Whooping Cranes and 1 colt consuming 16 individual vertebrates of at least 6 different species during the stopover. In total, we documented Whooping Cranes consuming 7 Channel Catfish (Ictalurus punctatus), 5 ray-finned fish (Actinopterygii), 1 sunfish (Centrarchidae), 1 carp/minnow relative (Cypriniformes), 1 perch relative (Percidae), and 1 Leopard Frog relative (Lithobates sp.). We estimated prey item lengths using the average exposed culmen measurements for adult Whooping Cranes and approximated their nutritional value using log-transformed length–weight regression equations with taxon-specific intercepts and slopes from secondary data sources. We estimated that aquatic vertebrate forage made up a significant portion of Whooping Crane daily energy requirements and provided substantial amounts of calcium, phosphorus, and protein not present at high levels in waste grains also consumed during migration. Additionally, we documented territorial behavior by adult Whooping Cranes during migration and evidence of adults teaching their colt to forage. Our study demonstrates the utility of photography and videography to natural history research and indicates that aquatic vertebrates may be a relatively regular part of Whooping Crane diet in the CPRV. RESUMEN.—La población de grullas trompeteras (Grus americana) de Aransas-Wood Buffalo migra aproximadamente 4000 km dos veces al año a través de las Grandes Llanuras (Great Plains) centrales, entre sus sitios de reproducción y sus sitios de invernada. Las grullas trompeteras dependen de los sitios donde hacen escalas para obtener lugares de descanso y adquirir los recursos calóricos necesarios para completar su migración, tales como, el área de hábitat crítico designada por USFWS en Central Platte River Valley (CPRV) de Nebraska. Esta área cuenta con un hábitat fluvial trenzado caracterizado por bancos de arena sumergidos de baja elevación que constituyen importantes zonas de descanso y alimentación para las grullas trompeteras migratorias. En el otoño de 2019, durante una escala de 11 días, registramos los alimentos consumidos en el área por las grullas trompeteras, utilizando fotografías y videos de largo alcance y análisis conductuales. Identificamos tres grullas trompeteras adultas y una joven consumiendo 16 vertebrados de al menos seis especies diferentes. En total, registramos grullas trompeteras consumiendo siete peces gato americanos (Ictalurus punctatus), cinco peces con aletas radiadas (Actinopterygii), un pez luna (Centrarchidae), un pariente del pez carpa/piscardo (Cypriniformes), un pariente de la perca (Percidae) y un pariente de la rana leopardo (Lithobates sp.). Calculamos la longitud de las presas usando el promedio del tamaño de culmen de las grullas trompeteras adultas, y estimamos el valor nutricional con ecuaciones de regresión de talla-peso transformadas logarítmicamente con intersecciones y pendientes de taxones específicos provenientes de una fuente de datos secundarios. Estimamos que el consumo de vertebrados acuáticos proporciona una parte significativa de las necesidades energéticas diarias de la grulla trompetera, y grandes cantidades de calcio, fósforo y proteínas que no están presentes en altos niveles, en los granos de desecho, que también se consumen durante la migración. Además, documentamos el comportamiento territorial de las grullas trompeteras adultas durante la migración, así como la evidencia de adultos enseñando a sus crías a alimentarse. Nuestro estudio demuestra la utilidad de la fotografía y videografía en la investigación de la historia natural e indica que los vertebrados acuáticos pueden ser parte de la dieta regular de la grulla trompetera en el CPRV

A Case Study of a Successful Lake Rehabilitation Project in South-Central Nebraska

Cottonmill Lake, a 17.4 ha impoundment located in Buffalo County, Nebraska, was a fishery dominated by common carp (Cyprinus carpio). As a result of the poor sportfish populations, angler participation in May and June of 1993 was low (503 ± 210 angler hours) and angler catch rates for all fish species (0.5 ± 0.4 fish/angler hour) was less than desired. In 1995, before rehabilitation, bluegill (Lepomis macrochirus) trap net catch per unit effort (CPUE) was 1.5 ± 0.9, largemouth bass (Micropterus salmoides) catch per hour of electrofishing was 8.0 ± 0.5, and channel catfish (Ictalurus punctatus) CPUE in gill nets was 7.5 ± 2.5. In 1999, the Nebraska Game and Parks Commission (NGPC) and city of Kearney completed a lake rehabilitation project at Cottonmill Lake by removing 84,995 m3 (300,000 ft3) of sediment and adding two islands and four breakwater jetties. Standardized NGPC fishery survey conducted in 2003, four years after rehabilitation, found a significant increase in number of bluegill (CPUE = 28.3 ± 7.4; p = 0.012; F = 12.86; df= 1) and largemouth bass (CPUE = 496.0 ± 5.8; p \u3c 0.001; F = 34.33; df= 1). In addition, angler participation in May and June 2006 was higher after rehabilitation (11,122 ± 1,333 angler hours), and angler catch rates for all species (1.5 ± 0.4 fish/angler hour) increased. The estimated angler expenditure while fishing at Cottonmill Lake during May and June 2006 increased to $367,026 in 2006 from an estimated$26,004 during May and June 1993

Population Characteristics of Co-Managed White Bass and Hybrid Striped Bass in Lake McConaughy, Nebraska

White Bass (Morone chrysops) and Hybrid Striped Bass (M. saxatillis × M. chrysops) populations often coexist in the same waterbody and are known to achieve different lengths, have differing reproductive success, and provide different opportunities for anglers. However, comparative population dynamics from systems where Moronids are managed with the same regulation is often lacking. This study aimed to assess the recruitment, mortality, and growth of these species from seasonal samples collected at Lake McConaughy in 2015 and fall 2016. White Bass demonstrated highly variable recruitment in Lake McConaughy despite stocking efforts (mean recruitment variability index = 0.157). Hybrid Striped Bass year class strength was also variable, but RVI was not calculated as the number of missing year classes exceed the number of present year classes. Total annual mortality estimates for Hybrid Striped Bass (39.7%) and White Bass (41.4%) were consistent with values reported in other populations, but both species were observed to achieve uncommon longevity. Both species exhibited sexual size dimorphism, and growth was moderate and consistent with average values presented for North American populations. This study provides insight into the population dynamics of two species with trophy potential managed by the same regulation in Lake McConaughy. Differences in growth patterns indicate the current regulation affects each species differently, and managers may be able to utilize this to inform decisions about management of coexisting Moronid populations

Food habits of imperiled Plains Topminnow and diet overlap with invasive Western Mosquitofish in the Central Great Plains

Plains Topminnow (Fundulus sciadicus) populations have experienced large declines throughout the Central Great Plains, with Western Mosquitofish (Gambusia affinis) introductions suggested as a contributing factor. There are limited studies identifying the food habits of Plains Topminnow and the trophic interactions with Western Mosquitofish. This study sought to determine if a diet overlap exists between the Plains Topminnow and the introduced Western Mosquitofish by identifying the feeding habits of both species. We analyzed diets from lentic and lotic populations of Plains Topminnow captured in August and found lentic topminnows employed a generalist diet while lotic topminnow selected for gastropods. Additionally, Western Mosquitofish diets from regionally proximate lotic and lentic populations also displayed a generalist diet consisting of benthic, littoral and terrestrial macroinvertebrates. The two species did not show overlapping diets based on Schoener’s Index. Therefore we suggest the introduced Western Mosquitofish do not likely impact Plains Topminnow populations through food resource competition

\u3ci\u3eDaphnia lumholtzi,\u3c/i\u3e an Exotic Zooplankton, Invading a Nebraska Reservoir

A limnological assessment project by the University of Nebraska at Kearney and the Nebraska Game and Parks Commission collected weekly vertical zooplankton tows during May through September 2002 at Harlan County Reservoir in Nebraska. Beginning on 5 August 2002, the exotic Daphnia lumholtzi (Cladocera: Daphniidae) appeared at a density of 0.04 1.1 in one of fifteen standardized sampling stations. By 6 September 2002, D. lumholtzi was found in all fifteen stations at an average density of 2.17 ± 3.10 1.1 with a site maximum density of 11.43 1.1 • Length measurements of D. lumholtzi ranged from 0.80 mm to 5.66 mm with a mean length of 2.38 ± 1.107 mm. During sampling, the abundance of D. lumholtzi increased relative to the native Daphnia retrocurva from less than 1 % to greater than 45% of all zooplankton collected. Our finding represents the first account in a Nebraska water system of D. lumholtzi, a native of Africa, Asia, and Australia, and shows a northern expansion in the Great Plains of this exotic species