FEEDING HABITS OF PACIFIC COD, GADUS MACROCEPHALUS, OFF EASTERN HOKKAIDO, NORTH JAPAN (14th Symposium on Polar Biology)

• Main Authors: ヤマムラ オリオ, ワタナベ カズトシ, シマザキ ケンジ, Orio YAMAMURA, Kazutoshi WATANABE, Kenji SHIMAZAKI
• Format: Report
• Language: English
• Published: Proceeding 1993
• Subjects: Pacific; Polar Biology; Proceedings of the NIPR Symposium on Polar Biology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=5184; http://id.nii.ac.jp/1291/00005184/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=5184&item_no=1&attribute_id=18&file_no=1

We collected a total of 336 specimens of Pacific cod, Gadus macrocephalus during April, May and June 1989-1992 off the eastern coast of Hokkaido. Examination of their stomach contents revealed that fishes (mainly walleye pollock, Theragra chalcogrammd) and decapod crustaceans (mainly crangonid shrimps) were major diet. The cod showed an obvious body size related dietary shift; the importance of shrimps (Neocrangon communis and Argis lar) and myctophid fishes for ≤300 mm individuals switched abruptly to walleye pollock and other fishes (e.g. Sardinops melanostictus, Laemonema longipes, stichaeid and cottid fishes) and octopus, Paroctopus spp. for larger individuals. The cod showed an obvious feeding periodicity with a peak of feeding during 0600-1200 h. The comparison of prey size and prey type (benthos and nekton) for different size classes of predators indicated that the cod diet is determined by predator-prey size relationship.