Swimming Behavior of Juvenile Yellowfin Tuna (Thunnus albacares) Around Fish Aggragate Devices (F.A.D.S) in the Philippines

Abstract

Three juvenile yellowfin tuna (22-26 cm FL) were monitored around a payao (FAD: Fish Aggregating Device) in Panay Gulf, the Philippines. A receiver was attached to the anchor line of the payao, and ultrasonic transmitters were implanted into the abdominal cavities of the fish. Juvenile yellowfin tuna swam within a limited shallow range during nighttime and dived to deeper waters, maximum 105 m, during daytime, then moved away from the payao at midnight. One juvenile yellowfin tuna was recaptured 2 days alter release by handline in the same payao, and two juvenile yellowfin tuna were recaptured 12 days after release by ringnet in another payao over 3 km away. These recaptures indicate that the fish were active enough to feed and swim, and also show the feasibility of undertaking telemetry studies on juvenile yellowfin tuna.