Predator Feeding Preferences for a Benthic Stream Fish: Effects of Visible Injected Marks

Externally visible injected marks provide valuable information to scientists, but their presence may increase an individual's susceptibility to predation. In a laboratory experiment, we evaluated the feeding preferences of rock bass ( Ambloplites rupestris ) and smallmouth bass ( Micropterus dolomieu ) for unmarked, green-VIE-marked, and yellow-VIE-marked fantail darters ( Etheostoma flabellare ). Although neither predator exhibited significant selectivity for a particular treatment (ANOVA, p>0.05), smallmouth bass appeared to prefer green-marked over control or yellow-marked darters. Contrasting diel feeding strategies may explain these preferences. In a mark/recapture field study, we examined the influences of mark color and mark location on predation rate by examining variation in darter recapture rates. Again, no significant differences were detected among treatments (ANOVA, p>0.05), but dorsal-marked darters had slightly lower recapture rates than did ventral-marked ones. The effects of mark color were insignificant and opposite to those found in the laboratory study, indicating that experimental preference may not equate to increased predation rate in the wild.