FISHERY BULLETIN: VOL. 84, NO. 1 



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Figure 2— Percentage volumes of stomach contents of the fish, crustacean, and 

 miscellaneous organism component for sockeye, pink, coho, and chinook salmon sampled 

 in Strait of Juan de Fuca during 1967-68. 



Coho ate greater numbers of fish than did chinook 

 salmon (Table 1), but chinook had a greater volume 

 of the stomach contents composed of fish (56% 

 chinook, 46% coho). This result suggests chinook eat 

 larger fish than coho (Table 2). As with coho, 

 euphausiids were the dominant invertebrate prey 

 type of chinook salmon, comprising 40% of a total 

 invertebrate volume of 44% of stomach contents. 

 However, euphausiids occurred significantly more 

 often in the diet of coho salmon than in chinook 

 salmon (x 2 = 4.73, P < 0.01). 



Fish were a more significant dietary component 

 of chinook and coho salmon than of sockeye and pink 

 salmon. Sand lance occurred significantly more often 

 in the diet of chinook and coho salmon than in the 



diet of sockeye and pink salmon (x 2 = 152.9, P < 

 0.01). Similar results were also found for herring (x 2 

 = 18.1, P < 0.01), rockfish (x 2 = 7.2, P < 0.01), and 

 mixed fish species (x 2 = 39.0, P < 0.01). Inverte- 

 brate prey were more significant in the diet of 

 sockeye and pink salmon than in that of chinook and 

 coho. Euphausiids occurred more frequently in the 

 diet of sockeye and pink salmon (x 2 = 199.3, P < 

 0.01), as did Parathemisto (x 2 .= 619.5, P < 0.01), 

 crab larvae (x 2 = 171.1, P < 0.01), and amphipods 

 (x 2 = 9.2, P < 0.01). There was no difference in 

 frequency of occurrence of crabs in the diet (x 2 = 

 0.01, P > 0.05) which occurred only at low levels 

 or not at all, but mysiids occurred more frequently 

 in the diet of chinook and coho salmon than in 



80 



