Food of Salmonid Fisbes of the 

 Western North Pacific Ocean 



Japan, Canada, and the United States 

 fonned the International North Pacific 

 Fisheries Coomission in 1953' The Conmis- 

 sion's primary concern is to study the 

 conservation and utilization of the fish- 

 eries resources of the northern Pacific. 

 As pjurt of the researches instituted by the 

 Ccmmission, the University of Washington 

 Department of Oceanography undertook to 

 study the food of salmonid fishes in the 

 oceanic stage of their life cycle. 



The purpose of the food -study program 

 was to detennine which animals vere impor- 

 tant to the diet of the salmon. This 

 knowledge would permit extensive research 

 into the distribution of such food orgeinisms 

 in the open ocean and, in turn, into the 

 distribution of salmon. The diets of three 

 species of Oncorhynchus are reported in 

 this paper: 0. nerka , the sockeye salmon; 

 0. keta , the chum sedmon; and 0. gorbuscha , 



the pink salmon. The diet of the king 

 salmon, 0. tshawytscha ; the silver salmon, 

 0. kisutch ; and the steelhead, Salmo 

 gairdneril , also were investigated, but the 

 data are insufficient to Justify inclusion 

 in this report. 



Material and Methods 



The fish used in this study were 

 purchased by the United States Fish and 

 Wildlife Service from the Japanese oceanic 

 gill -net fishery. Table 1 gives the loca- 

 tion and date of catch, number of fish in 

 the catch, and the sex and fork length of 

 the fish. 



For purpose of comparison, the fish- 

 ing areas are grouped into three major 

 regions (Fig. 1): 



Fl£ui« 1 — Region* of capture for fish used in this study. 



