Bull. Jpn. Soc. Fish. Oceanogr. 68(2), Page 97-105, 2004   Autumn migration of oval squid Sepioteuthis lessoniana in Toyama Bay, the Japan Sea, assessed by release and recapture experiment Seishi Hayashi Toyama Prefectural Fisheries Research Institute, Namerikawa, Toyama, 936-8536, Japan e-mail: seishi.hayashi@pref.toyama.lg.jp Release and recapture experiments of tagged oval squid Sepioteuthis lessoniana were conducted in Toyama Bay in order to assess their migration in autumn. A total of 1753 squids were tagged and released in September to November during the period from 1991 to 1993. Eighty-one squids were recaptured in Toyama Bay within 57 km from the release site and within 17 days after the release. No westward migration out of Toyama Bay was observed. These results suggest that the shoals of this squid keep staying during autumn to winter in Toyama Bay, where they are fished or die. Key words: oval squid, Sepioteuthis lessoniana , tag and release, migration, Toyama Bay