Movements and Behaviour of Target Fishes in the Marine Ranching Area Determined by Biotelemetry

Abstract

Artificial reefs considered as one of the stock enhancement programs in coastal and offshore waters, have been suggested as a tool for reef conservation and rehabilitation. Wild fishes are associated with artificial reefs in two marine ranching areas (Jeju and Tongyeong), South Korea but the knowledge of habitat use and fish movement around them is unclear. Monitoring fine-scale movement by acoustic telemetry information could provide a better understanding about the ecological function of artificial reefs for these fishes. In this study, two wild adults black rockfish (Sebastes schlegeli, T1 and T2) were tagged with acoustic transmitter tags and digital micro data logger, released then passive and manual (active) tracking for hours in addition to compare both artificial reefs and natural habitats in Tongyeong marine ranching center during different periods. Manual tracking was accomplished using a fishing boat with an omnidirectional hydrophone, receiver and GPS unit. T1 showed an association with artificial reefs while T2 released in one area without artificial reefs, it had wide displacements (>1 km in the last detected point), suggesting that the rockfish probably searched for the homeward direction. Red seabream (Pagrus major, J1) monitored in Jeju marine ranching area exhibited more activity at dusk hours than during the daylight hours, its stay in place around some artificial reefs was observed according to some tracking records. In general, fine-scale studies may be used as references to defining determined areas for no-take marine reserves and provide guidelines that could optimize artificial reefs placement as well as promote in areas even not carried out. Furthermore, the application of biotelemetry in this study, has offered a powerful means for the remote monitoring of free-swimming wild fish.