TABLE 1. — Dates, locations, station information, and sample sizes of stomach samples of Pacific 

 whiting taken from the northwest Pacific Ocean, 1967 and 1980. 



1 Number of tows at bottom depths > 1 00 m are given in parentheses 



2 MW= midwater trawl. BT = bottom trawl. 



3 Stomachs containing food. Number of empties in parentheses. 



feeding discontinuity. A total of 258 stomachs were 

 collected at seven different times of day (Table 2). 



Fish showing signs of regurgitation were discarded 

 from samples. Lengths were recorded for fish with 

 stomachs containing food. The stomachs of adult fish 

 were then excised and placed in muslin bags with a 

 specimen card containing fish length and station 

 information. Juvenile fish were placed whole in 

 muslin bags for later stomach excision in the 

 laboratory. All samples were preserved in a 10:1 

 seawater/formaldehyde mixture. 



Because of incomplete records of numbers of empty 

 stomachs sampled on two cruises in 1980, that data 

 set could not be used for daily ration calculations. In 

 1967, however, numbers of empty stomachs at each 

 station were recorded along with corresponding 

 fish lengths. 



Fish lengths were converted to weights using the 

 weight-length relationship for Pacific whiting, sexes 

 combined (Traynor 1 ): 



w K = 0.004774 



/ 3.0947 



'J. Traynor, Fishery- Biologist, Northwest and Alaska Fisheries 

 Center. National Marine Fisheries Service, NOAA, 2725 Montlake 

 Blvd. E., Seattle, WA 98112, pers. commun. December 1982. 



TABLE 2.— Summary of a diel series of Pacific whiting stom- 

 ach samples obtained on RW John M. Cobb, 14-15 July, 1967 

 off the Washington coast lat. 47 : 19'N, long. 124°33'Wata 

 bottom depth of 65 m. 



Stomachs were analyzed individually in the 

 laboratory, with the exception of the fall 1980 sam- 

 ples which were analyzed by composite groups. Prey 

 items were identified to the lowest practical taxon, 

 and damp weight and number of each prey taxon per 

 stomach or composite of stomachs were recorded. In 

 1967, there was some loss of information on the num- 

 ber of prey in some taxa because no attempt was 

 made to count certain prey items when they showed a 

 fair degree of digestion. 



Food of Pacific Whiting 



Euphausiids, including Thysanoessa spinifera and 

 Euphausia pacifica, were the dominant food of 

 Pacific whiting in 1967, constituting 72.2 and 90.2% 

 by weight of the diet of Pacific whiting taken off 

 Oregon and Washington, respectively (Table 3). In 

 1980, euphausiids were also the predominant item in 

 the diets of Pacific whiting <200 mm in length off 

 California (100% by weight) and of Pacific whiting 

 350-449 mm long off Oregon (99.6% by weight). 



Schooling fish were also important dietary com- 

 ponents for Pacific whiting. Northern anchovy, 

 Engraulis mordax, comprised 16.4% by weight of the 

 diet of Pacific whiting in summer 1967 off Oregon. In 

 spring 1980 off Oregon, eulachon, Thaleichthys 

 pacificus, comprised 22% by weight of the diet of 

 450-549 mm Pacific whiting and 79.6% by weight of 

 the diet of 550+ mm fish. Pacific herring, Clupea 

 harengus pallasi, dominated the diets of Pacific whit- 

 ing taken in summer 1980 off Washington and Van- 

 couver Island, constituting 54.2 and 67% by weight of 

 the 450-549 mm and 550+ mm whiting size 

 groups, respectively. 



Other fish items were predominantly flatfish and 

 rockfish, Sebastes sp. Pandalid shrimp, including 

 Pandalus jordani, comprised <5% by weight of the 



630 



