Journal of Oceanography, Vol. 64 (No. 2), pp. 185-194, 2008
Naoki Tanimata1*, Orio Yamamura2, Yasunori Sakurai1 and Tomonori Azumaya2
1Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan
2Hokkaido National Fisheries Research Institute, Kushiro 085-0802, Japan
(Received 18 June 2007; in revised form 26 September 2007; accepted 2 October 2007)
Abstract: The food habits of the dominant myctophid Stenobrachius leucopsarus were examined in the central basin of the Bering Sea in relation to oceanographic conditions, in summer 2002 and 2003 and spring 2006. S. leucopsarus exhibited an ontogenetic and seasonal dietary shift. In spring, small fish (≤40 mm) preyed mainly on Neocalanus flemingeri/plumchrus whereas large fish fed mainly on Neocalanus cristatus. In summer, small fish preyed mainly on Metridia pacifica whereas large fish fed mainly on euphausiids (Thysanoessa spp.). In the summer of 2003, when water temperature in the epipelagic layer (≤100 m) was warmer, reflecting the prevalence of the Alaskan Stream, small-sized S. leucopsarus showed a higher stomach content index, perhaps reflecting the greater abundance of M. pacifica. Thus, the present study shows that the physical variability in the epipelagic layer affects not only diets but also feeding performance of micronekton.