Behavior of Skipjack Tuna, Katsuwonus pelamis, as Determined by Tracking with Ultrasonic Devices

Abstract

A 50-kHz transmitter was placed in the stomach of a 44-cm (estimated) skipjack tuna, Katsuwonus pelamis, at Kaula Bank, Hawaii. With a few interruptions the fish was tracked from August 30 to September 6, 1969. The fish made nightly journeys of 25–106 km away from the bank and, with one exception, returned to the bank every morning to remain there for the day. Another skipjack tuna, about 40 cm long, was tracked for 12 hr at Penguin Bank, Hawaii. It also stayed at the bank during the day and left at night. Both fish swam close to the surface at night but swam at various depths during the day. The repeated morning returns of the skipjack tuna to Kaula Bank imply that skipjack tuna can navigate and that they have a sense of time.