Behavior of large yellow croaker (Larimichthys crocea) in pen aquaculture as measured by meter-scale telemetry

To understand the behavior of the large yellow croaker (Larimichthys crocea) in a pen aquaculture setting, three individuals in each of two experimental groups were telemetered in meter scale by four cable-synchronized hydrophones. The ultrasound pinger system was applied to track the motion of six L. crocea for 24 h using two fixation methods, i.e., implanting tags in the abdomen (the in vivo implantation group) and hanging tags on the dorsal fin (the dorsal fin suspension group). Pingers repeated unique 62.5 kHz coded signals at 5 s intervals along with a pressure signal. The results showed that fish tagged with internal pingers took approximately 3 h longer than externally tagged fish to stabilize in their behavior, as measured by depth utilization; the horizontal movements of the test fish were mostly found outside of the fence, where the test fish performed round-trip swimming, with the least probability of appearing near the production platform and more frequent activities in the feeding areas.