Table 2.— Mean estimated percentage volume of foods in stomaciis of Pacific cod in southeastern Alaskan waters, July 1977 (stomach 



fullness one-fourth or greater). 



(Stichaeidae), and eelpouts (Zoarcidae), which are 

 not as distinguishable as walleye pollock and may 

 have been eaten more frequently than the values 

 in Table 3 indicate. Flatfish (Pleuronectidae) were 

 easily recognized and, because few were found, 

 were probably not an important food for Pacific cod 

 in these waters during July. 



Crab and shrimp were the next most important 

 foods. The volume of crab in Pacific cod stomachs 

 was greater than the volume of shrimp; however, 

 the frequency of occurrence of shrimp was greater 

 than the frequency of occurrence of crab. Snow 

 crab, Chionoecetes bairdi, the crab most often 

 eaten by Pacific cod, were juveniles and ranged 

 from 5 to 42 mm carapace width (mean, 20 mm). 

 As many as 30 snow crabs were found in some 

 stomachs. Dungeness crab. Cancer magister, was 

 the only other crab eaten in more than incidental 

 numbers. Pagurids (hermit) and other anomuran 

 crabs were rarely eaten. Pandalid shrimp, par- 

 ticularly Pandalus tridens and P. borealis, were 

 more frequently eaten than either crangonid or 

 hippolytid shrimp, and all three families of shrimp 

 were often found together in stomachs. 



Other invertebrates were found in the Pacific 

 cod stomachs, but their volumes and frequencies 

 were small. Cephalopods were in more than 14% of 

 the stomachs but constituted only 3.1% of the 

 mean volume. Often only the cephalopod's horny 

 beaks were present; however, whole Octopus sp. 

 formed the bulk of the stomach contents of a few 

 Pacific cod. Gammarid amphipods were in 14% of 

 the stomachs. Pelecypods, mostly Nuculana sp., 

 were infrequently eaten. The large polychaete 

 Aphrodita sp. ("sea mouse") was found in some 

 stomachs and composed most of the volume for 



970 



the polychaetes. Planktonic foods, such as 

 euphausiids or mysids, were rarely found and 

 then, only in trace amounts. 



At all locations, the size of the Pacific cod af- 

 fected the kinds of food eaten (Table 2). Small 

 Pacific cod («60 cm) fed mostly on crab and 

 shrimp; only 17% of the estimated volume of their 

 stomach contents was fish. Large Pacific cod ( >70 

 cm long) fed predominately on fish (66% by vol- 

 ume). The diet of intermediate-sized Pacific cod 

 (61-70 cm) was transitional between the diets of 

 the small and large Pacific cod. 



Sex of Pacific cod did not appear to be related to 

 the major foods eaten (Table 2). Fifty-nine percent 

 of the Pacific cod were females, 38.7% were males, 

 and 2.3% were of unidentified sex. Females had a 

 mean of 68.6 cm TL; males, 65.2 cm TL. The minor 

 differences that did arise between the foods of each 

 sex can probably be attributed to the greater mean 

 length of females. 



Foods of Pacific cod in outside waters were dif- 

 ferent from foods of those in inside waters (Tables 

 2, 3). Pacific cod in outside waters ate a larger 

 volume of crabs (mostly juvenile snow crab) than 

 those in inside waters; however, in inside waters, 

 the volume of shrimp (particularly pandalid 

 shrimp) in the stomachs was much higher than in 

 outside waters. These differences in the volume of 

 foods eaten were especially pronounced for small 

 and intermediate-sized Pacific cod. All sizes of 

 Pacific cod ate more fish in the inside waters than 

 in the outside waters. Pacific herring, especially, 

 were heavily consumed in inside waters. 



The two gear (gill nets and traps) probably did 

 not significantly bias the results. Comparison of 

 foods in Pacific cod caught by gill nets and foods in 



