Shark and Ray Abundance (IMAGE) University of California - Santa Barbara Caption Predation pressure affects how far herbivorous fish will feed from reefs. These ‘halos’ are larger when apex predators keep smaller predators in check, decrease when smaller sharks proliferate, and grow again when these sharks decline. Without any sharks, the entire area gets mowed bare. Credit Dedman & Moxley et al. Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.