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<br />processes. In Aggus and Morais (1979), catostomid standing crops were used to <br />develop regionalized reservoir fisheries predictive equations. <br /> <br />t <br /> <br />Model 4 <br /> <br />Use the appropri ate reservoi r descri pt i on and sui tabi 1 ity rating 1 i st <br />from McConnell et al. (1982) to calculate an HSI for white suckers in planned <br />reservoirs. <br /> <br />Model 5 <br /> <br />This model was developed after testing the original riverine model in the <br />summer in LaGarde Creek, St. Vrain Creek, and Big Thompson River, Colorado. <br />The model was expanded to include additional variables to better assess adult <br />habitat, spawning habitat and cover. This model follows a life requisite <br />approach, as used in the original riverine model (page 26). Many of the <br />variables are the same used in the original riverine model (turbidity, pH, <br />dissolved oxygen, temperature [adult/juvenile, fry, embryo], riffle velocity, <br />riffle depth, percent cover, percent pools). The new variables include: <br />riverine spawning substrate; pool depth; percent shade; gradient; pool <br />velocity; and spawning distance. Propst (1982b) felt cover was most important <br />in determining the suitability of a stream for white suckers. <br /> <br />This alternate riverine model combines the variables into components of <br />water quality, reproduction, and cover (Fig. 3), which are used to derive the <br />habitat suitability index. Reasons for placing individual variables in <br />specific components are described below. f <br /> <br />Water quality component. Refer to riverine model description (page 14). <br /> <br />Reproduction. Spawning temperature (V6) is included because it influences <br /> <br />spawning migrations, reproductive success, and hatching rates. Larval tem- <br />perature (Vs) is included because of its influence on larval growth and <br /> <br />activity. Riffle velocity (V7) and riffle depth (Va) are important in spawning <br /> <br />site selection. White suckers prefer to spawn in moderately fast, shallow <br />riffle areas, although they are tolerant of a relatively wide range of riffle <br />depths. Spawning substrate (V12) is included because spawning has been <br /> <br />observed over sand and gravel substrates and not over mud or boulders. Spawn- <br />ing habitat distance (V17) is included because we assume the distance fish <br /> <br />must mi grate to spawn i nfl uences reproductive success. Whi te suckers can <br />migrate to and spawn successfully in smal~-streams that do not contain habitat <br />for adults, but do contain spawning habitat and habitat that can support <br />sizable fry and juvenile populations. Quantitative data on the effect of <br />distance on reproductive success are not available, thus, this variable is <br />based solely on professional judgment. <br /> <br />24 <br /> <br />f <br />