Feeding Behavior of Pacific Salmon Juveniles in the Northern Okhotsk Sea during the Summer and Autumn of 1994-2000

摘要

In the epipelagic layer (0-200 m) of the northern part of the Okhotsk Sea, the major nekon species are walleye pollock (Theragra chalcogramma), Pacific herring (Clupea pallasii), capelin (Mallotus villosus), northern smoothtongue (Leuroglossus schmidti), and lesser salmonids and cephalopods (juvenile squids). These species serve as key elements in energy/substance flows (Shuntov et al. 1993; Lapko 1994). Biomass changes of Pacific salmon are caused by their foraging and prespawning migrations. The major species are pink (Oncorhynchus gorbuscha) and chum salmon (O. keta) among Pacific salmon (Lapko 1994). The biomass of Pacific salmon in summer is higher than, the biomass of Pacific salmon juveniles in autumn, because most Pacific salmon are prespawning individuals.