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1 <br />' another order of magnitude. Predation with both clear water and no alternate prey reduced <br />' survival three orders of magnitude. It is unlikely that these conditions would prevail all season in <br />the field, but these simulations suggest that when periods of clear water or low food availability <br />occur, mortality from red shiner predation is increased. <br />' The scope of the IBM was restricted by a lack of data. amenable to inclusion in a <br />' mechanistic model. For example, existing data for modeling the relationship between discharge <br />and availability of prey for larval Colorado squawfish in backwaters were not available. This <br />' component was originally proposed because it has an intuitive link to ecosystem management: <br />' manage dischazge to provide warm, persistent backwaters that provide food-rich habitat for larval <br />Colorado squawfish. Despite omission from the IBM, this component has great conceptual <br />importance and quantitative field studies should be conducted so that the indirect relationship <br />' between dischazge and growth of Colorado squawfish is better understood. When information on <br />' this relationship and other relevant factors (e.g., role of other predator species) becomes <br />available, it can be incorporated into the modeling approach presented here. <br />' Water temperature regime is correlated with dischazge. Thus, water temperature can be <br />' used as a surrogate for dischazge. The IBM is well-equipped for evaluating the influence of <br />water temperature because the temperature-dependent growth equation is incorporated in the <br />1 <br />model and any temperature regime can be simulated. U.S. Geological Survey hydrologic data <br />' could be used to describe relationships between dischazge and water temperature, and effects of <br />' dischazge manipulations could be explored. <br /> <br />' 23 <br /> <br />