Encounter Rates of a Juvenile Reef Fish with Small and Predatory Fishes

Abstract

Previous studies have shown that predation by large fishes (> 200 mm TL) is responsible for greater mortality rates of juvenile Acanthochromis polyacanthus on continuous than on patch reefs. Yet 43% of mortality on continuous reefs cannot be explained by these piscivores. I hypothesized that small predatory fishes are a source of this unaccounted mortality and tested the prediction that juvenile A. polyacanthus encounter small predatory fishes at a greater rate on continuous than on patch reefs. Of all fishes encountered by A. polyacanthus, fishes known to be potential predators of A. polyacanthus were most frequently encountered. There was a trend for A. polyacanthus to encounter these species at a greater rate on continuous than on patch reefs, but this was not supported by the analyses. This result highlights current uncertainty about sources of mortality in juvenile reef fishes. Future research is needed to establish the relative contribution of alternate sources of mortality to overall mortality so that the predictive power of hypotheses about processes that control reef fish abundance can be improved.