• trap sampling site 



 cillnet sampling site 



Figure 2. — Locations where Pacific cod were sampled in inside 

 waters, southeastern Alaska, July 1977. 



Table l. — Summary of samples of Pacific cod caught in gill nets 

 and traps in southeastern Alaskan waters, July 1977. Each site 

 was sampled once. 



next day. Usually, stomachs were removed from all 

 Pacific cod caught, but random subsamples were 

 taken from a few large catches. Stomachs and re- 

 gurgitated or undigested food in the esophageal 

 and mouth areas were preserved in Formalin.^ The 

 sex of each Pacific cod was identified, if possible, 

 and the total length (TL, tip of snout to end of tail) 

 was measured. 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Estimated percentage volume of major food 

 categories and frequency of occurrence of each 

 food were determined. The volume of each major 

 food category (i.e., fish, pandalid shrimp) was vi- 

 sually estimated to the nearest 5% for each 

 stomach that arbitrarily appeared to be at least 

 one-fourth full. Foods in stomachs less than one- 

 fourth full were listed only as present and often 

 were slowly digested items, such as fish otoliths or 

 cephalopod beaks in trace amounts. No other 

 allowances were made for stomach fullness. When 

 pooling results, I averaged equally the percent- 

 ages of each food in all stomachs one-fourth or 

 more full. Visual estimates of the percentage vol- 

 ume of food in each category were generally within 

 10% of percentages determined by actual mea- 

 surements of displacement volume. I identified all 

 foods in all stomachs to the lowest taxonomic level 

 possible and calculated the overall frequency of 

 occurrence (expressed as the percentage of 

 stomachs containing the food) of each food. 



Volume data on each major food category were 

 analyzed to determine whether relationships 

 existed between foods eaten by Pacific cod and 1) 

 size and sex of Pacific cod, 2) the location at which 

 they were caught (inside waters vs. outside 

 waters), and 3) the type of gear. I arbitrarily sepa- 

 rated the Pacific cod into three total length 

 categories to determine whether the different 

 foods eaten were related to size of Pacific cod. The 

 size categories were ^60 cm, 61-70 cm, and >70 

 cm. Too few samples were taken at different 

 depths in the same localities to allow analysis of 

 Pacific cod foods by depth. 



Results 



If data from all areas are combined, regardless 

 of size and sex of Pacific cod and gear type, fish 

 were the most important food of Pacific cod both 

 volumetrically and in frequency of occurrence. 

 Fish accounted for more than 40% of the stomach 

 contents by volume (Table 2) and were in nearly 

 60% of the stomachs (Table 3). The largest percent- 

 age of fish in the stomachs was unidentifiable; 

 however, of the identifiable fish, Pacific herring 

 and walleye pollock, Theragra chalcogramma, 

 were eaten most often. Pacific herring ranged from 

 9 to 25 cm long (mean, 18 cm); walleye pollock, 

 identified by their large and characteristic 

 otoliths, were juveniles and ranged from 10 to 31 

 cm long (mean, 22 cm). Some of the unidentified 

 fish were probably Pacific herring, pricklebacks 



969 



