Spatial movement of black sea bream Acanthopagrus schlegelii around the oyster farming area in Hiroshima Bay, Japan

In order to obtain information for preventing oyster spats predation, we investigated the horizontal and vertical movement patterns of black sea bream Acanthopagrus schlegelii inhabiting an oyster farming area in Hiroshima Bay by active tracking. Seven adult fish equipped with depth transmitters were tracked for 65 days around the oyster farming area. Six of the seven fish were found in the oyster rafts for a cumulative duration of 55 days. The daily movement distance and minimum convex polygon home range of these fish were 0.13–0.78 km/day and 0.11–1.14 km2, respectively. The swimming depth of these fish were mainly between 1 and 15 m, which coincided with the depths of the submerged oyster wires. Our observations suggest that black sea bream inhabiting the oyster farming area in Hiroshima Bay are highly dependent on the spatial arrangement of the oyster rafts.