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Identify data gaps and methodological problems associated with data collection as part <br />of the Upper Basin Recovery Program; 5) Use the models and the parameter estimates <br />obtained from the data synthesis step to determine the current status for all identifiable <br />subpopulations of the endangered fish; and 6) Make the models available to state and <br />federal managers to perform simulations outlining likely outcomes of a myriad <br />management scenarios or objectives that might be developed. <br />A generic model was developed (initially using Mathcad and later translated to Quattro- <br />Pro) based on geomorphic reaches identified during the first workshop as the smallest <br />spatial scale. The Upper Basin was. divided into three river segments comprised of the <br />Yampa/Green River (above the confluence), the Colorado River segment, and the <br />segment below the confluence of the Green and Colorado Rivers to Lake Powell. The <br />model was generated to be as specific as data would allow and includes sex ratio, <br />survivorship means and variances for larvae, YOY, 1-, 2- and 3-yr old fish and adults. <br />Initial population values for each age class as well as carrying capacity values for each <br />geomorphic section are also used as initiation values in all models. While the model <br />can be used in a very specific manner (e.g., to model only 2-yr old fish in a particular <br />reach), it can also be parameterized to model the Upper Basin as a single population. <br />Following the initial mode! development phase, workshops were held at Utah State <br />University and at Lake Powell to develop species-specific model attributes and to <br />identify data sources available for parameter estimation. Using that input, we identified <br />ix <br />