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<br />0009~7 <br /> <br />In the report by Chadwick and Associates (1989) five species of <br />fish were modelled. Four of the five species are used in this <br />example to demonstrate how the guilding approach can be used to <br />develop a target flow. The red shiner was not used because it's <br />WUA versus discharge curve was very similar to the sand shiner. <br /> <br />Due to the differences in the WUA curves between the killifish <br />and the sand shiner, both species where incorporated along with <br />the juvenile channel catfish and the adult common carp. All four <br />species used in this analysis have very different WUA versus <br />discharge curves (Figure B2) and could be used to represent <br />different guilds based on a combination of both depth and <br />velocity. <br /> <br />The forage fish composite curve peaks at a discharge of 1,500 <br />cfs. A flow of 1,500 cfs WDuld provide approximately 97, 92, 81, <br />and 65 percent optimum physical habitat for the sand shiner, <br />juvenile channel catfish, adult common carp, and plains <br />killifish, respectively. A flow of 1000-1100 cfs provides at <br />least 70 percent optimum physical habitat for all four species <br />and 100 percent optimum physical habitat for sand shiners (Figure <br />B2). Flows below 800 cfs result in significant declines in the <br />percent of optimum physical habitat for all species modelled <br />except the plains killifish which peaks at approximately 400 cfs. <br />A flow of 400 cfs results in significant declines in the <br />percentage of optimum physical habitat available to other <br />species/guilds. <br /> <br />The above described procedure does not take into account other <br />flow related variables which affect habitat suitability such as <br />water temperature and specialized habitats. Water temperature is <br />related to flow and is believed to be a major factor in <br />determining both the diversity and abundance of the Platte River <br />fishery and as such must be considered when developing a "target <br />flow". For example, 400 cfs may provide optimum habitat for <br />plains killifish during some time of the year, but when air <br />temperatures begin to increase, flows of greater magnitude are <br />required to prevent or reduce both the frequency and duration of <br />elevated lethal water temperatures. <br /> <br />Elevated water temperatures affect fish in a variety of ways. <br />Fish physiology can be altered during these high water <br />temperature conditions influencing survival rates, growth rates, <br />embryonic development, and susceptibility to parasites and <br />diseases (Fry 1971; Andrews and Stickney 1972; Matthews et al. <br />1982; Bakanov et al. 1987, Armor 1991). Elevated water <br />temperatures can also affect metabolism, fluid-electrolyte <br />balance, and the acid-base relationship within fish (Lantz 1970; <br />Islam and Strawn 1975). Fish behavior can also be altered ~n <br />respect to habitat utilization activities, distribution, and <br />species interactions (Crawshaw 1977; Matthews and Hill 1979; <br />Adams et al. 1982; Stauffer et al. 1984). Changes in water <br /> <br />10 <br />