Anti-predatory performance in hatchery-reared red tilefish ( Branchiostegus japonicus) and behavioral characteristics of two predators: Acoustic telemetry, video observation and predation trials

Abstract

The anti-predatory performance of hatchery-reared red tilefish ( Branchiostegus japonicus) using tube-shaped burrows was studied together with the behavioral characteristics of potential predators, the white spotted conger ( Conger myriaster) and the marbled rockfish ( Sebastiscus marmoratus). White spotted conger were released in Maizuru Bay (Kyoto, Japan) and tracked using acoustic telemetry; they were also observed in a tank using video recording. White spotted conger tended to remain inside shelters, but occasionally swam outside briefly at night. Attacking behavior of predators and predation avoidance behavior of red tilefish were also recorded in a tank. Red tilefish construct tube-shaped burrows into which they retreat to avoid attack. White spotted conger wandered around the tank, often invading the burrows to prey on red tilefish. Predation by white spotted conger occurred at night. Inside the burrows, red tilefish were not easily caught and were able to escape through the other entrance of the tube-shaped burrow. Marbled rockfish, on the other hand, pounced on red tilefish immediately after prey recognition, ambushing their prey near the burrow entrance. Predation by marbled rockfish was frequently observed around dusk and dawn, but some red tilefish that remained inside burrows survived. White spotted conger is nocturnal and probably an olfactory predator, whilst marbled rockfish is crepuscular and an ambush predator. For stock enhancement of red tilefish, the construction of tube-shaped burrows and their diurnal behavior around the burrows are desirable characteristics in reducing predation by both white spotted conger and marbled rockfish.