Study of fish behavior using acoustic fish tags and wireless tracker

To understand the behaviors of restocking and releasing fish, two kinds of restocking and releasing fishes grey snapper (Lutjanus argentimaculatus) and black snapper (Acanthopagrus schlegelii) were tracked by using ultrasonic tags at Seven-star Bay in Shenzhen from July 16 to July 31, 2016. The signal of the tags was received by buoy wireless data transmission receivers, and the fish behavior was analyzed preliminarily. A grey snapper and a black snapper had complete data but the other two grey snappers were lost after being tracked for 4 d. Both the grey snapper and the black snapper had obvious circadian rhythm and hiding behavior, active in a small area (about 100 m) near the released place. The data obtained during daytime (7:00–20:00) were significantly less than at night (20:00–7:00). The black snapper was active at 9–10 m layer in daytime and at 8–9 m layer at night; the grey snapper was active at 2–3.5 m layer in daytime and at 1–2 m layer at night. The study promotes application of tracking by tags in fish behavior research and effect evaluation of restocking and releasing and sea ranching construction.