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Figure 1. Observer efficiency estimates (number of tagged fish seen relative to the number known to be present) versus horizontal underwater visibility for 3 years of periodic surveys in the Salmo River, British Columbia. Although untransformed data are depicted here, regression analyses were conducted using arcsine-square-root-transformed observer efficiency data

@@@@Regression data for individual years were not prescreened for outliers because error analysis for observer efficiency regressions with such few data points should not be considered realistic (Thompson 2003)...