the total volume. Squid were found in 36.7 

 percent of the stomachs but represented 

 only 6.7 percent of the food volume. In 

 Region B only three items, amphipods, fish, 

 and crustacean larvae, contribured more 

 than 10 percent each to the total volume of 

 the pink salmon diet. Mphipods, again the 

 major food item, accovinted for 49.0 percent 

 of the total volume. Pteropods, although 

 found in a greater percentage of the stom- 

 aches in Ftegion B than in Region A, account- 

 ed for only 3*5 percent of the volume. In 

 Region C each of fomr items, copepods, 

 euphausiids, emphipods, and fish, contri- 

 buted more than 10 percent to the total 

 food volume. Pteropods, although found in 

 41.1 percent of the stomachs, accounted 

 for only 5.5 percent of the total volume. 



Comparison of feeding behavior 

 of the species 



Fish taken in the same area, unless 

 otherwise noted in table 1, were also taken 

 with the same geax and in the same set • 

 Therefore, It is reasonable to assiuue that 

 all three species In a particular area had 

 the same food supply available. Conse- 

 quently, differences in stomach contents 

 were attributed to differences in feeding 

 behavior. 



Figure 2 summarizes graphically the 

 percentage of the totsLL volume contributed 

 by the different food organisms, and figure 

 3 summarizes the frequency of occurrence 

 of the different food items in the diets of 

 the three species of salmon from each of 

 the three regions. 



Region A : Amphipods were the most 

 important single food item to the sockeye 

 and pink salmon. The most important food 

 item for the chum SEilmon was crustacean 

 larvae. Only two items, amphipods and 

 crustacean larvae, contributed in excess 

 of 10 percent each to the total volume of 

 the sockeye '8 diet. The remaining items 

 contributed to the diet a total volume of 

 only 9-4 percent. Each of five items con- 

 tributed volumes in excess of 10 percent to 

 the chum's diet, and four groups bad a 

 similar Importance to the diet of the pink 

 salmon. Thus, the sockeye appeeo^d to be 

 the most selective of the three species, 

 whereas the chum and pink appeared to be 

 more omnivorous feeders. Further differ- 

 ences might be evidenced by the fact that 

 the frequency of occurrence of amphipods 



was almost the same in the diets of the 

 three species, while the volumetric contri- 

 bution of amphipods was about five times as 

 great for the sockeye and pink salmon as it 

 was for the chum. Copepods, entirely absent 

 In the diet of the pink and sockeye, were 

 found in chum salmon stomachs. Fish also 

 were considerably more important to the diet 

 of the chum and pink salmon than to the 

 sockeye. 



Region B : For all species, amphipods 

 were the most Important food item. Only 

 one item, the amphipods, contributed a 

 volimie in excess of 10 percent to the sock- 

 eye's diet. Four groups each contributed 

 volumes in excess of 10 percent to the 

 chum's diet, while three items have a simi- 

 lar Importance to the diet of the pink 

 salmon. The amphipods occur with about 

 equal frequency in the diet of all three 

 species; however, volumetrlcally the amphi- 

 pods were almost three times as Important 

 to the sockeye as to the chum salmon. The 

 sockeye again demonstrated a greater selec- 

 tivity than either the chum or the pink 

 salmon. 



The frequency of occurrence of cope- 

 pods and euphausiids in the stomachs of the 

 three species weus another indication of the 

 difference in their feeding behaviors. Cope- 

 pods occurred in 44.4 percent of the chum 

 stomachs, but in only 8.2 percent of the 

 sockeye and 5«1 percent of the pink salmon 

 stomachs. Euphausiids occurred in 55-1 per- 

 cent of the chum stomachs, but In only 28.8 

 percent of the pink and l6.4 percent of the 

 sockeye stomachs. Fish were of far greater 

 Importance to the pink salmon than to either 

 the chum or the sockeye. Squid were of con- 

 siderable Importance to the chimi diet, but 

 played only a minor role In the diet of the 

 pink and sockeye s£ilmon8. 



Region C : Copepods were the most 

 Important food item to both the sockeye and 

 pink salmon, ailthou^ euphausiids also con- 

 tributed substantially to the diets. Eu- 

 phausiids and fish foimed the bulk of the 

 chimi salmon diet. Three groups, copepods, 

 euphausiids, and fish, contributed in excess 

 of 10 percent each to the diet of the sock- 

 eye, while each of four groups contributed 

 volumes in excess of 10 percent to the diets 

 of the chum and pink salmon. Thus, the 

 sockeye appeared to be the most selective 

 of the three species In Region C For eill 

 the species, amphipods appeared In a high 



