Table 3. — Frequency of occurrence of food items ^1.0% in 

 stomachs of 492 Pacific cod, southeastern Alaskan waters, July 

 1977 (based only on stomachs containing food).' 



'Also present at frequencies <1.0%: Fishes — Lumpenus maculatus. L. 

 sagitta, Hippoglossoides elassodon. Lepidopsetta bilineata, Lycodes bre- 

 vipes. L. palaeris. Dasycottus setlger, Coryphaenoides sp,, Ra/a sp, embryo, 

 unidentified fish eggs: shrimps — Pandalus stenolepls. P. goniurus. P. 

 platyceros: crabs — Oregonia gracilis. Lopholithodes sp., Labidochirus 

 splendescens: cephalopods — Rossia pacifica, pelecypods — Siliqua patula. 

 Chlamys rubidus. Serripes groenlandicus: polychaetes — Abarenicola sp.: 

 gastropods — Lora sp., Neptunea sp.: barnacles — Lepas sp.. unidentified bar- 

 nacles: sipunculids; hydroids; ophiuroids; nemerteans; anthozoans; porife- 

 rans: foraminifera: unidentified invertebrate eggs. 



Pacific cod caught by traps was difficult because 

 the two gear, which tend to catch different sizes of 

 fish, were frequently set at different localities or 

 depths (Table 1; Figures 1, 2). However, when traps 

 and gill nets caught similar-sized fish in the same 

 areas, foods were also similar (see Table 4, Pacific 

 cod 61-70 cm TL in outside waters and >70 cm TL 

 in inside waters). In other cases, locality rather 



than gear appeared to be the overriding factor 

 determining kinds of food eaten. Of the 24 Pacific 

 cod sampled in the 61-70 cm TL gill net category in 

 inside waters, 15 were taken in Idaho Inlet. There, 

 Pacific herring apparently were so abundant that 

 all sizes of Pacific cod caught in both gill nets and 

 traps fed upon them. 



The volume of gammarid amphipods in the 

 stomachs of Pacific cod caught in traps may have 

 been artificially high. Gammarid amphipods were 

 almost exclusively found in Pacific cod caught in 

 traps (Table 4). These amphipods were probably 

 attracted to the baited traps where Pacific cod in 

 the traps fed upon them. In contrast, other inver- 

 tebrates, such as shrimp or crabs, appeared to be 

 found equally in stomachs of Pacific cod caught in 

 either traps or gill nets. 



Discussion 



The major foods identified in this study are simi- 

 lar to the major foods of Pacific cod in other regions 

 of the North Pacific Ocean. Walleye pollock and 

 Pacific herring were among the predominate fish 

 species in stomachs of Pacific cod from Asian 

 waters, and the crab Chionoecetes sp. was the most 

 common invertebrate (Moiseev 1953). Flatfish and 

 the sand lance, Ammodytes sp., however, appeared 

 frequently in Moiseev's samples of Pacific cod 

 stomachs but were rare or absent in my samples. 

 The results of Jewett's (1978) study are in close 

 agreement with the results of my study: he found 

 fish, crab, and shrimp to be the most frequent 

 items in Pacific cod stomachs collected near 

 Kodiak, Alaska, during summer. In Jewett's study, 

 walleye pollock was the most common fish eaten, 

 and snow crab was the most common crab; Pacific 

 herring were rarely eaten. 



Other studies have demonstrated, as did my 

 study, that larger codfishes become more piscivo- 

 rous. As the size of Atlantic cod, Gadus morhua, 

 increased, the diet changed from smaller inver- 

 tebrates to larger fish (Powles 1958; Popova 1962; 

 Rae 1967). Both Moiseev (1953) and Jewett (1978) 

 found similar trends in their investigations of 

 Pacific cod: cod < 50-60 cm long ate mostly crusta- 

 ceans; cod >60 cm primarily ate fish. 



Some of the differences I found in foods of Pacific 

 cod in outside and inside waters may be related to 

 the availability of pandalid shrimp and Pacific 

 herring. The results of my food study appear to 

 reflect an increased abundance of both of these two 

 foods in inside waters. Data from exploratory 



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