Data were analyzed using Analyses of Variance (ANOVA). Prior to analysis data were tested for homogeneity of variance and when necessary Log10 transformations were applied to ensure there was homogenous variation between the test groups. For each analysis the dependent variable was explored in terms of the level of predation, the river the fish came from and the interaction between these two factors. A probability value of 0.05 or less was used to determine the statistical significance of the comparisons.