TABLE3.— Frequency of occurrence of food items found 

 in at least 1% of stomachs of 541 walleye pollock from 

 Auke Bay and Fritz Cove, southeastern Alaska, 1979- 

 80 1 . (Table does not include an additional 36 stomachs 

 that were empty.) 



Food item 



Mysids 



Acanthomysis pseudomacropsts 

 Acanthomysis nephrophthalma 

 Neomysis kadiakensis 

 Neomysis raytt 

 Neomysis sp 

 Pseudomma truncatum 

 Unidentified mysids 

 Euphausnds 

 Thysanoessa raschn 

 Thysanoessa spimfera 

 Thysanoessa longipes 

 Unidentified euphausnds 

 Copepods 

 Metndia sp. 

 Calanus sp. 

 Euchaeta elongata 

 Aevdius sp. 



Cenrropages abdommahs 

 Unidentified copepods 

 Hypernd amphipods 

 Parathemisto sp. 

 Unidentified hypemds 

 Shrimp 

 Pandalid shrimp 

 Pandalus borealis 

 Pandalus tndeos 

 Unidentified pandalids 

 Crangonid shrimp 

 Crangon communis 

 Crangon dalh 

 Crangon franciscorum 

 Crangon sp 



Unidentified crangonids 

 Hippolytid shrimp 

 Eualus avtnus 

 Unidentified hippolytids 

 Unidentified shrimp 

 Gammand amphipods 

 Oetocerotidae 

 Cyphocans challengen 

 Unidentified gammands 

 Cumaceans 

 Eudorella sp 

 Leucon sp. 



Unidentified cumaceans 

 Polychaetes (unidentified) 

 Fish 

 Theragra chalcogramma 

 Unidentified fish 

 Cephalopods 

 Pelecypods 

 Isopods 

 Larval shrimp 

 Larval brachyuran crab 

 Larval anomuran crab 



Frequency of 

 occurrence (%) 



54 



19 



5 



18 



3 



1 



7 



9 



47 



31 



1 



1 



17 



42 



20 



15 



6 



6 



2 



6 



29 



6 



23 



28 



1 1 



3 



1 



9 



14 



2 



2 



1 



6 



4 



4 



1 



3 



5 



25 



4 



1 



21 



21 



16 



2 



3 



12 



10 



1 



8 

 1 

 1 

 1 

 1 

 1 

 1 



'Also present at frequencies <1 %: Mysids — Pseudomma berkeleyi. 

 Meterythrops sp., Holmesiella anomula, Stilomysis grandis; pandalid 

 shrimp — Pandalopsts dispar: crangonid shrimp — Crangon alasken- 

 sis.Argis crassa; fish — Clupea harengus paltasi, Osmendae, Pleuro- 

 nectidae, Stichaeidae; cumaceans — Cumella sp.; copepods — 

 Calanus cnstatus. Pseudocalanus sp.; hypernd amphipod — Pnmno 

 macropa: cephalopod — Octopus sp.; unidentified gastropods; Pagu- 

 ndae — Pagurus ochotensis. brachyuran crab; barnacle cyprid; larval 

 fish — Thaleichthys pacificus; Holothuroidea — Molpadia intermedia: 

 algae. 



walleye pollock consumed primarily euphausiids, 

 mysids, shrimp, and fish. Thus, of the crustaceans, 

 euphausiids were a major food in all studies, whereas 

 the types of other crustaceans varied among the in- 



vestigations. Shrimp, an important food for walleye 

 pollock both in my study and near Kodiak Island 5 , 

 were found only in very small amounts in Bering Sea 

 fish. In all studies, organisms that are strictly benthic 

 (e.g., clams and crabs) were conspicuously scarce in 

 the diet. 



In fishes, the size of prey generally increases as the 

 size of predators increases (Nikolsky 1963), and this 

 appears to be true in walleye pollock. In my study, 

 small walleye pollock ate mostly planktonic crus- 

 taceans, particularly euphausiids, mysids, and 

 copepods; large walleye pollock generally ate larger 

 prey, such as shrimp and fish (Table 2). 

 Intermediate-sized walleye pollock were transitional 

 in their diet and ate a combination of large and small 

 foods. In the Bering Sea, juvenile walleye pollock 

 (<350 mm) also ate mostly euphausiids or copepods, 

 whereas larger walleye pollock ate larger foods, 

 primarily fish (Takahashi and Yamaguchi 1972; Mito 

 1974; Bailey and Dunn 1979). Walleye pollock 

 became increasingly cannibalistic with increase in 

 size in the Bering Sea: More than half the food of fish 

 >550 mm FL was smaller walleye pollock (Takahashi 

 and Yamaguchi 1972). In my study, cannibalism was 

 observed in only 1% of the stomachs (Table 3); 

 however, few walleye pollock >450 mm SL were 

 examined. 



Sex of the fish had little effect on their diet (Table 

 2). The diets of male and female walleye pollock were 

 nearly identical in percent volume of each food 

 category. 



Walleye pollock apparently fed year-round (Table 

 4): In any one season only 4-8% of all fish had empty 

 stomachs. In any one size group, no more than 14% of 

 the fish had empty stomachs in any season. In con- 



5 P. Livingston, Northwest and Alaska Fisheries Center, Natl. Mar. 

 Fish. Serv., NOAA, 2725 Montlake Boulevard East, Seattle, WA 

 98112, unpubl. data. 



TABLE 4.— Seasonal feeding activity of walleye pollock shown by 

 percent of fish with empty stomachs, Auke Bay and Fritz Cove, 

 southeastern Alaska, 1979-80. 



Size 



Stomachs 

 examined 



Spring Summer Fall 



Winter 



640 



