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Discussion Our simulations provide a valuable assessment of potential predation by northern pike on Colorado squawfish. These approximations are most useful for asking the question: "Can northern pike predation alter the population dynamics of Colorado squawfish by limiting recruitment?" The flexibility of this simulation framework allows easy enhancements to the model by incorporating new information that this modeling exercise identified as important. Thus, the model acts as an interactive, iterative tool for both research and management. The model formalizes analysis of existing information and provides an initial quantitative evaluation of an array potentially important processes. Processes that exert strong influences on the community structure or population dynamics of native species are identified along with critical data needs. Our simulations identified pike abundance, size structure, seasonal growth, and diet as important for refining resolution on the temporal impact of pike on juvenile Colorado squawfish. Seasonal diet composition data are important for allocating predation effects to the appropriate prey species. Our simulations simply modeled a range of possible predation scenarios with Colorado squawfish representing 1-25% of the annual diet by weight for northern pike, and a nominal run using existing diet data. Clearly, the model can be refined and updated with improved field data to include effects of seasonality, habitat segregation, predator size, and predator abundance into the model. The refinements would allow us to identify and quantify critical predation periods and locations that are imposed on different squawfish cohorts by northern pike. Similar approach could be used to evaluate the importance of other predators as well. The model can also predict how changing dam operations at Flaming Gorge might affect predation rates due to changes in water temperature and habitat use.