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HSI determination. HSI = (CF x CC x CWQ2.x CR2 x COT)1/7 ~ or If CwQ or CR is <_ 0.4, then the HSI_.equals the lowest of the _. _... following: CwQ, CR, or the above equation. , Sample data sets using lacustrine-HSI model are listed in Table 3. Interoretino Model Outouts The proper interpretation of .the HSI produced by the models is one of comparison. If two water bodies have large differences in HSI's, then the one with. the higher HSI should be able: to support more catfish than the water body with the lower HSI ,_, given that the model assumptions have not been violated. The actual differences in-HSI that indicate-a true difference- in-carrying capacity are unknown and likely to be high: We have aggregated a large number. of variables into a single index-with little or no quantitative information on how the variables interact to effect carrying capacity. The probability that we have made an error in our assumptions on variable interactions is high. However, we believe the model is a reasonable hypothesis of how the selected variables interact to determine carrying capacity. Before using the model, any available statistical models, such as those described under model 3 in the next section, should be examined to determine if they better meet the goals of model application. Statistical models are likely to be more accurate in predicting the value of a dependent variable, such as standing crop, from habitat related variables than the HSI models described above. A statistical model is especially useful when the habitat variables in the data set used to derive the model have values similar to the proposed model application site. The HSI models described above may be most useful when habitat conditions are dissimilar to the statistical model data set or it is important to evaluate changes in variables not included in the statistical model. The sample data sets consist of different variable values (and their corresponding SI score), which although not actual field measurements, are thought to represent realistic conditions that could occur in various channel catfish riverine or lacustrine habitats. We believe the HSI's calculated from the data reflect what carrying capacity trends would be in riverine or lacus- trine habitats with the characteristics listed in the respective data sets. 22