Keith D. Koupal

Keith D. Koupal
The Nebraska Game and Parks Commission

Ph.D.

About

71
Publications
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361
Citations

Publications

Publications (71)
Article
Coves are part of the mosaic of fish habitats in many U.S. reservoirs, but over time these coves may be disconnected from the main reservoir for varying durations due to the buildup of sediment berms at the mouth that are higher than reservoir elevations. Our four‐year study (2017 – 2020) of five coves of Harlan County Reservoir, Nebraska, across t...
Article
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 US...
Article
Water chemistry can vary spatially and temporally within a riverscape (i.e., reservoir, rivers, and tributaries) due to different surficial geologies, groundwater influences, surrounding land use, habitat type (i.e., reservoir or river), and water residence time. Microelemental signatures may be absorbed by calcified structures of fish and have bee...
Article
Full-text available
The article discerns variable population dynamics as depicted by seasonal sampling within the same reservoir for walleye and channel catfish.
Article
Fish samples collected during different times of the year can be subject to various biases, but the influence of sampling during different seasons on population dynamics and yield metrics in large reservoirs is not well reported. This study compared the age structure, growth, mortality, and yield estimates of Channel Catfish Ictalurus punctatus and...
Article
Full-text available
The plains topminnow (Fundulus sciadicus) is an endemic Great Plains stream fish that has experienced declines in geographic range and local abundance. Due to these declines, the species has been considered for Federal protection and designated with conservation status in states throughout its historic range. The reasons for declines are likely sim...
Article
Full-text available
Fish samples collected during different times of the year can be subject to various biases, but the influence of sampling during different seasons on population dynamics and yield metrics in large reservoirs is not well reported. This study compared the age structure, growth, mortality, and yield estimates of Channel Catfish Ictalurus punctatus and...
Article
Full-text available
Freshwater drum (Aplodinotus grunniens) represent one of the most widely distributed fish species in North America. Identifying biotic and abiotic factors that influence larval freshwater drum densities can improve understanding of early life history. Our objective was to investigate correlations between annual peak density of larval freshwater dru...
Article
Sampling is often standardized with regard to time and space to monitor population characteristics. Effective sampling of large reservoirs can be complicated by the inherit bias of habitat variability along the reservoir gradient. Our objective was to assess spatial and seasonal distribution patterns of target and non‐target fish species in a large...
Article
Perrion MA, Kaemingk MA, Koupal KD, Schoenebeck CW, Bickford NA. 2019. Use of otolith chemistry to assess recruitment and habitat use of a white bass fishery in a Nebraska reservoir. Lake Reserv Manage. XX:XX–XX. Managing fisheries that exhibit variable annual recruitment is challenging, and maintenance stockings are often prescribed to minimize in...
Article
Full-text available
Stopover sites provide important forage resources and protection from predators to the Aransas-Wood Buffalo population of Whooping Cranes (Grus americana) as they migrate 4000 km across the Great Plains each spring and fall. Given the Whooping Crane’s expansive migration corridor, sensitivity to human disturbance, small population size, and protect...
Article
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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...
Article
Much attention has been given to describing how abiotic factors impact the population dynamics of Yellow Perch Perca flavescens, especially during early life history; however, the impacts of biotic factors are less understood. In this study, we simplified the community assemblage to reduce interspecific competition and gain a better understanding o...
Presentation
Full-text available
Dams act as an anthropogenic barrier to fish movement, and these barriers can influence population dynamics, gene flow, and spawning success. Fish passage structures, such as lifts, natural passages, or a series of pools, are often constructed to aid fish movement. However, the success of fish passing through these structures is rarely evaluated, e...
Article
Full-text available
The ontogenetic diet shift to piscivory can be energetically beneficial for fish growth and allows larger, more energetically profitable prey to be consumed. A shift to piscivory may be easier for longer individuals within a cohort due to larger gape size, and an early shift is likely advantageous, potentially leading to increased growth rates and...
Article
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Understanding consumption patterns and preferences of particular life stages for fish species can clarify potential dietary overlap and identify energy flow within aquatic communities. Age-0 white bass (Morone chrysops) have been documented to consume a variety of prey items and zooplankton are a common occurrence. The importance of particular zoop...
Preprint
Full-text available
Background. The North American prairie biome is considered one of the most endangered ecoregions. Prairie fishes have been affected by many anthropogenic disturbances, including the construction of bridges and culverts as road crossings over streams. The objective of our study was to test fish assemblage characteristics upstream and downstream of s...
Preprint
Background. The North American prairie biome is considered one of the most endangered ecoregions. Prairie fishes have been affected by many anthropogenic disturbances, including the construction of bridges and culverts as road crossings over streams. The objective of our study was to test fish assemblage characteristics upstream and downstream of s...
Article
Full-text available
The Sandhills of Nebraska are a unique ecotone that is home to hundreds of natural lakes. These water bodies are known to be productive and susceptible to inundation from non-native common carp (Cyprinus carpio). Excessive populations of common carp typically require renovation of the system; however, little background has been published on the rel...
Article
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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 s...
Presentation
Full-text available
Adult White Bass are piscivorous and therefore available prey is restricted with gape width limitations. Limited information is available about the physical morphometric gape width limitations of this species, particularly related to the consumption of Alewife. Alewives were stocked into Lake McConaughy, Nebraska in 1986 in order to provide a prey...
Article
Full-text available
Gizzard shad (Dorosoma cepedianum) are an influential forage fish and driver of zooplankton resources in many reservoirs. The ability to identify the biotic and abiotic factors that influence the timing of elevated gizzard shad densities can be important to better utilize this forage fish and manage sport fish. The objective of this study was to in...
Article
Full-text available
Plains topminnow Fundulus sciadicus are endemic to the Great Plains (USA), and because of declines in their geographic range and local abundance, are granted protection throughout their native range. Experimental reintroductions were conducted to improve conservation techniques and enhance the long-term outlook for plains topminnow persistence in N...
Article
Full-text available
Regionally proximate waters in the Sandhills of Nebraska are known to have distinctive alkaline conditions. However, little is known about the seasonal variability that exists for abiotic conditions and zooplankton communities within these same waters. Th is study assessed two highly alkaline and four moderately alkaline lakes for seasonal trends i...
Article
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Conservation of lotic fishes requires consideration of complex patterns among a changing mosaic of fish assemblage structure at multiple spatial scales. Studies have demonstrated the influence of localized competition and predation among stream fishes, but researchers have been largely unable to determine to what extent interspecific interactions a...
Article
Chemical batch marks with compounds such as oxytetracycline hydrochloride (OTC) can be useful for estimates of stock contribution. However, no information currently exists on the feasibility of marking fingerling White Bass Morone chrysops with OTC. The objectives of this study were to determine the level of mortality on White Bass when immersed in...
Article
Full-text available
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 o...
Article
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Humans have baited wildlife such as white-tailed deer (Odocoileus virginianus) for generations with the primary purpose of increasing hunting harvest success. Baiting regulation changes are often considered by state management agencies as they pertain to hunting opportunity, fair chase, and disease risk. Cervids require a variety of minerals to sup...
Article
Full-text available
Abstract Humans have baited wildlife such as white-tailed deer (Odocoileus virginianus) for generations with the primary purpose of increasing hunting harvest success. Baiting regulation changes are often considered by state management agencies as they pertain to hunting opportunity, fair chase, and disease risk. Cervids require a variety of minera...
Article
Full-text available
The popularity of walleye Sander vitreus fishing has resulted in the development of specialized regulations that are designed to protect these fisheries. In the case of Sherman Reservoir, Sherman County, Nebraska, the walleye population provides a sportfishing opportunity and serves as broodstock for the state. In 2009, for the primary purpose of p...
Article
Full-text available
Stream fragmentation can be detrimental to lotic fish species by preventing important life history movements. The maximum swimming speed and jumping ability of 10 stream fish species were evaluated to describe potential water velocity and height barriers to fish movement. A 10-L swim tunnel was used to test maximum swimming performance and an artif...
Article
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Catch rates are commonly used to indirectly index population density, e.g., nighttime electrofishing to survey Largemouth Bass Micropterus salmoides populations. However, the relationship between catch rate and population density must be known in order for catch rate to serve as an accurate index. We sought to determine if Largemouth Bass electrofi...
Article
Full-text available
The establishment of nonnative species and subsequent replacement of native species is among the greatest threats to freshwater biodiversity worldwide. However, little is known of the effects that invasive species have on individual species and specific mechanisms by which species displacement occurs. The expansion of western mosquitofish Gambusia...
Article
Full-text available
Movement behaviors attributed to spawning, dispersal, or altered habitat availability are essential to the ecology of many lotic fishes and, although considerable research has described movements of sport fish, little is known about the movement patterns of nongame species. Streams and rivers, wherein plains topminnow Fundulus sciadicus are prevale...
Data
Full-text available
Cobble substrate for walleye (Sander vitreus) spawning was added at Sherman Reservoir, Nebraska, in January 2008. We evaluated changes in relative adult walleye abundance and egg density in response to the cobble substrate and estimated site fidelity of adult walleye during the spawning seasons of 2007, 2008, and 2009. A 15% increase in electrofish...
Article
Full-text available
Harlan County Reservoir, located in south-central Nebraska, entered a drought in 2003, providing an opportunity to monitor the effects of drought on the zooplankton community in this irrigation reservoir. We sampled the zooplankton community at 15 standardized locations every other week from April through the third week of October from 2003-2011. T...
Article
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Over 2 years, we examined the survival of stocked advanced fingerling Yellow Perch Perca flavescens involving over 16 stocking events in eight lakes in Nebraska. The survival of stocked fish was estimated with respect to both handling mortality during stocking and predation by Largemouth Bass Micropterus salmoides. Handling mortality during stockin...
Article
The growth of age-0 fishes influences survival, especially in temperate regions where size-dependent over-winter mortality can be substantial. Additional benefits of earlier maturation and greater fecundity may exist for faster growing individuals. This study correlated prey densities, growing-degree days, water-surface elevation, turbidity, and ch...
Conference Paper
The Nebraska Game and Parks Commission would like to establish yellow perch angling opportunities in south central Nebraska through the use of stocking fingerling. Studies have indicated that predation mortality can contribute up to 100% of stocked fish mortality. The predation mortality of stocked yellow perch in eight barrow pits was assessed by...
Article
Full-text available
Fisheries managers applied rotenone to Mormon Island West in August of 2010 to renovate a fish community that was hypothesized to be unbalanced (i.e., dominated with gizzard shad and common carp) based on standardized survey results. We estimated species-specific biomass following the lake renovation to provide a baseline biomass estimate for a san...
Article
Understanding the environmental factors that regulate fish recruitment is essential for effective management of fisheries. Generally, first-year survival, and therefore recruitment, is inherently less consistent in systems with high intra- and interannual variability. Irrigation reservoirs display sporadic patterns of annual drawdown, which can pos...
Article
Full-text available
A technique for mass-marking fish was evaluated that forces fluorescent pigment into dermal tissue with compressed air. A five month trial was conducted where mark retention, readability, and marking mortality were evaluated with six fish species that represent a variety of taxonomic groups. Approximately 100 of each species were marked; a percenta...
Article
Full-text available
The plains topminnow Fundulus sciadicus appears to be experiencing reductions in geographic range and local abundance, which has led to regional protection throughout its native range. Conservation of this species may require introductions to reestablish populations at known historic locations. Therefore, a pond was constructed during September 200...
Article
Full-text available
The U.S. Fish and Wildlife Service has adopted two different pitfall trap protocols to survey the endangered American burying beetle, Nicrophorus americanus. One protocol uses a transect of eight pitfall traps that prohibit bait contact over the course of three trap nights. The other protocol uses buckets that allow for bait contact over a five nig...
Article
Full-text available
Globally, riverine fishes are affected by degradation of habitat, stream alterations, lost stream connectivity and introduction of non-native species. The plains topminnow Fundulus sciadicus, a small stream-dwelling fish, currently does not have a federal conservation status in the USA; however, anecdotal reports have suggested its decline for the...
Article
Full-text available
A new gear for sampling walleye Sander vitreus eggs, egg sampling disks, is described, and the ability of these disks to estimate walleye egg density on mud, cobble, and rip-rap substrates is demonstrated. Each egg sampling disk was a concave steel disk covered with outdoor carpet. The ability of the disks to estimate walleye egg density and total...
Article
Full-text available
During certain times of the year high densities of larval fish can impact the aquatic community. The specific role of freshwater drum (Aplodinotus grunniens) is not known but larval freshwater drum can be abundant in some systems and have been shown to feed on zooplankton. To assist with understanding the role larval freshwater drum play in reservo...
Article
Many aquatic organisms survive by filter feeding from the surrounding water and capturing food particles. We developed a laboratory exercise that allows students to measure the effects of filtering by fresh water mussels on water turbidity. Mussels were acquired from Wards Scientific and exposed to a solution of baker's yeast. Over a period of one...
Article
Full-text available
Gizzard shad (Dorosoma cepedianum) are prolific spawners that can influence reservoir communities. Larval gizzard shad may compete with larval recreational fish for zooplankton resources. Therefore, it is necessary to determine larval gizzard shad dynamics and food habits to better understand their potential for competition with larval recreational...
Article
Full-text available
Understanding the extent and depth of rotenone impacts on all trophic levels is essential to effective aquatic management. We examined changes in water quality tenets and zooplankton communities following the establishment of 3 ppm rotenone concentration in a Nebraska barrow pit. Dissolved oxygen initially decreased 57% and subsequently increased 2...
Article
Full-text available
The objective of this study was to determine the horizontal and vertical distribution of zooplankton in Harlan County Reservoir in order to assist in developing an appropriate zooplankton sampling regime for this and similar Nebraska irrigation reservoirs. Samples were collected at 16 sites distributed across 3 zones of the reservoir monthly in Apr...
Conference Paper
In this study we will examine the intrapopulation variability in growth of age-0 walleye in Harlan County Reservoir. Growth can be an important indicator of recruitment as the length of age-0 fish after that first growing season may influence over-winter survival. Similar to other irrigation reservoirs in Nebraska, Harlan County Reservoir has a low...
Article
Full-text available
Increased anthropogenic disturbance to watersheds and rivers is exacerbating the effects of oscillating wet-dry periods common in the Midwestern United States, consequently impacting the maintenance and health of lake and reservoir systems. A change in flow regime should affect water quality parameters in reservoirs, but few data exist to document...
Article
Full-text available
Cobble substrate for walleye (Sander vitreus) spawning was added at Sherman Reservoir, Nebraska, in January 2008. We evaluated changes in relative adult walleye abundance and egg density in response to the cobble substrate and estimated site fidelity of adult walleye during the spawning seasons of 2007, 2008, and 2009. A 15% increase in electrofish...
Article
Full-text available
Note: Out results suggested that mature male walleye electrofishing CPUE was a better indicator or where eggs were deposited that mature female walleye gill net CPUE.
Article
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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 desi...
Article
Full-text available
After the introduction of hybrid striped bass (white bass Morone chrysops × striped bass M. saxatilis) into Harlan County Reservoir, Nebraska, gill-net catch per unit effort (CPUE) of walleyes Sander vitreus appeared to decline while that of white bass remained stable. This result prompted the question of whether these three species can be managed...
Article
Full-text available
From June to September in 2004 and 2005, we sampled twice per week from the irrigation canal below the dam to determine entrainment of crappies (Pomoxis spp.) from Sherman Reservoir, Sherman County, Nebraska. The estimated total loss from the reservoir was about 1.0 million crappies per year. During both years more crappies were released during nig...
Article
Full-text available
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 l-1...
Article
The Colorado Division of Wildlife and Colorado State University teamed up to develop a modified suitability index to guide stocking decisions of tiger muskellunge (northern pike Esox Indus × muskellunge E. masquinongy). A categorical-based index stemming from historical stocking success, literature references, and logic was deemed the most appropri...
Article
Spawn-taking efforts for walleyes Stizostedion vitreum in Colorado were used to evaluate gear selectivity in terms of catch per unit effort (CPUE) and sex ratio. Seasonal electrofishing CPUE ranged from 28 to 197 walleyes/h, whereas gillnetting CPUE ranged between 0.5 and 3.0 walleyes/net-night. Corresponding sex ratios (male:female) for these gear...
Article
Full-text available
Weight and length data for tiger muskellunge Esox lucius x Esox masquinongy were solicited from biologists across the continent to develop a 75th-percentile standard weight (Ws) equation for the hybrid. Only 27 populations (N = 1,124 fish) from 9 states yielded adequate data sets for this process. We used a bootstrap technique to demonstrate that t...
Article
Full-text available
During spawning operations for walleye (Stizostedion vitreum) in 1993 and 1994 three dilutions of extended semen were used and hatching success was compared with that obtained from fresh semen. Semen : extender ratios of 1:2, 1:4, and 1:6 were found to compare favorably with fresh semen. In 1993, fresh semen produced the highest hatching percentage...
Article
Thesis (M.S.)--Colorado State University, 1993. Includes bibliographical references.

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