Abstract
Summary The longtail tuna, Thunnus tonggol (Bleeker) had been known from Japan by a single specimen by the name of T. rarus Kishinouye (1915), which is a synonym of the former. In 1968, some 40 years after the first record, the longtail tuna were found trapped in sardine set-net at Kundatai, Wakasa Bay, Japan Sea, numbering about 1400 and 1000 on the 3rd and 24th respectively, September. The same species of tuna were caught in the set-net at Odashukuno in the same bay on the 4th of the month, which numbered 9 and measured 48.6 to 51.4 cm in fork-length. The nonrecognition of the species in Japanese waters in the past may be ascribed to the misidentification of the young of the species with those of either T. thynnus or T. albacare.
