The feeding habits of the Pacific bluefin tuna, Thunnus orientalis were examined based on the stomach contents of 330 specimens caught by offshore large purse seine fishery in the southern sea of Korea, 2011. The size of Pacific bluefin tuna used in this study ranged from 34.1 to 67.3 cm in fork length (FL). The percentage of empty stomachs was 41.8%. The main prey items were Pisces and Cephalopoda based on percentage IRI (index of relative importance). The main fish preys were Trachurus japonicus, Bregmaceros japonicus, Engraulis japonicus, and Cephalopoda were Todarodes pacificus, Loligo edulis, Watasenia scintillans. T. orientalis showed ontogenetic change in diet composition. Although Pisces dominated the diet of all length classes the portion of Cephalopoda was relatively higher in size between 40 and 50 cm other than length classes. In terms of seasonal variation in feeding habits, Pisces was the main prey group in all seasons, but Cephalopoda was also frequently consumed during spring and autumn based on %IRI.

• 윤상철 | Sang Chul YOON
• 유준택(국립수산과학원 독도수산연구센터) | Joon Taek YOO (Dokdo Fisheries Research Center, National Institute of Fisheries Science, Pohang, 37709, Korea)
• 이성일(국립수산과학원 독도수산연구센터) | Sung Il LEE (Dokdo Fisheries Research Center, National Institute of Fisheries Science, Pohang, 37709, Korea) Corresponding author
• 김장근(국립수산과학원 독도수산연구센터) | Zang Geun KIM (Dokdo Fisheries Research Center, National Institute of Fisheries Science, Pohang, 37709, Korea)
• 최광호 | Kwang Ho CHOI