Keith D. Koupal

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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. Total(More)
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 night(More)
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 intraand interannual variability. Irrigation reservoirs display sporadic patterns of annual drawdown, which can pose a(More)
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 April, May,(More)
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 percentage with(More)
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 electrofishing(More)
1 Introduction Fisheries managers have used rotenone for over 100 years (Solman 1950, Kiser et al. 1963). The product rote-none is derived from the natural toxic properties from the roots of several different derris plant species that are located in tropical regions (Ling 2002). The toxins work by blocking mitochondrial electron transport at the cellular(More)
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