Table 3. — Percentage by weight of prey items in the stomachs of Pacific whiting, 1967 and 1980, off the west coast of North 

 America and summary of average stomach content weight (not including empty stomachs) 1 . 



*T indicates trace amounts of food. i.e. <0 1 % by weight of the diet 



Pacific whiting diet in all cases. Other shrimp eaten 

 included Cragon sp., Pasiphaea pacifica, and Serges- 

 tes similis. Other invertebrates were predominantly 

 crab megalops larvae. 



In terms of general prey categories, Pacific whiting 

 in 1967 off Oregon ate proportionally more fish, 

 especially northern anchovy, than did whiting in 

 1967 off Washington (Fig. 2). The diets of similar- 

 sized Pacific whiting (450-549 mm) taken in 1980 off 

 Oregon and Washington- Vancouver Island, however, 

 contained an even greater proportion of fish (Fig. 3), 

 but of different species. A shift in major dietary com- 

 ponent from euphausiids to fish occurred as the 

 length of Pacific whiting increased during spring and 

 late summer of 1980. Diets of Pacific whiting >550 

 mm consisted of 90.27c fish by weight. 



To illustrate the switch in food from euphausiids to 

 fish as the length of Pacific whiting increased, the 

 percentage frequency of occurrence of Pacific her- 

 ring in Pacific whiting stomachs was plotted against 

 Pacific whiting length for the late summer 1980 sam- 



100 



50 



Oregon Washington 



N = 202 N = 1228 



491 503 



Mean fish length (mm) 



Figure 2.— Percentage by weight of major prey categories in the 

 diet of Pacific whiting, Merluccius productus, taken off Oregon and 

 Washington, summer 1967. 



pies (Fig. 4). A steady increase in the occurrence of 

 Pacific herring is noticeable up to the 561-580 mm 

 whiting length interval. Thereafter, the curve 



631 



