SGER: Between-Reef Movements of Predators and Density-Dependent Mortality in Reef Fish

Oregon State University, Corvallis OR

Investigators

Abstract

Previous work by the investigator showed that transient predators (schools of jacks) are capable of density-dependent predation on newly-settled coral reef fish (Chromis cyanea). This study will use new telemetry techniques to help answer fundamental questions about how predators can regulate local populations of marine fish, leading to a better understanding of both fish population dynamics and also potential impacts of fishing and other human activities. The investigator will capture, tag, and acoustically track up to 20 small bar jack, following their movement (along with their associated schools) for 5 weeks during August and September 2000. The study area, in the Bahamas, will be a matrix of 32 natural and 16 artificial reefs, where prey density can be experimentally manipulated. The goal is to determine: whether tagged jacks spend more time at reefs with high prey densities, as previously documented using remote video samples; whether jacks move randomly or systematically among reefs; and what the overall range of movement of the predator is. The data should provide new insights on the behavioral mechanisms by which predators cause density-dependent mortality and lead to more detailed studes that separate the relative roles of aggregative vs. functional responses in predator-prey dynamics among marine fishes.