FISHERY BULLETIN: VOL. 84, NO. 4 



The pink shrimp, Pandalus jordani, fishery off 

 Oregon was one of the most economically viable fish- 

 eries during the late 1970s with landings in excess 

 of 26,000 t in 1978. Subsequent to that time, pink 

 shrimp landings have declined, with slightly over 

 2,000 t being landed in 1984 (Saelens and Zirges 

 1985). The purpose of this study was to describe the 

 dietary habits of the Pacific hake and, in particular, 

 to determine whether predation by Pacific hake on 

 pink shrimp could explain some of the fluctuations 

 seen in pink shrimp landings. 



MATERIALS AND METHODS 



In August and September 1983, during the Na- 

 tional Marine Fisheries Service (NMFS) West Coast 

 Groundfish Survey, Pacific hake stomachs were 

 sampled from 41 hauls taken during daylight hours 

 between Coos Bay, OR, and Grays Harbor, WA (Fig. 

 1). Tows were of 0.5-h duration using a Nor'eastern 5 

 high-opening bottom trawl equipped with roller gear 

 which has an approximate horizontal opening of 13.4 

 m and vertical opening of 8.8 m. Further details of 

 the sampling regime can be found in Gunderson and 

 Sample (1980) and Weinberg et al. (1984). Between 

 5 and 15 individuals of each sex from a 5 cm size 

 class (30-34 cm, 35-39 cm, 40-44 cm, 45-49 cm, 50-54 

 cm, 55 + cm) were sampled from each haul where 

 practical. A total of 466 stomachs were extracted 

 at sea and placed in cheesecloth bags. Stomachs with 

 evidence of regurgitated contents were not included 

 in the sample. Stomachs were preserved in a 10:1 

 solution of seawater to Formalin. 



Stomach Content Analysis 



In the laboratory, stomachs were transferred to 

 ethyl alcohol and examined under a dissecting micro- 

 scope. Stomach fullness and degree of digestion 

 were visually estimated and given a qualitative 

 rating (0-4 from empty to distended, and from un- 

 recognizable to recently consumed). Contents were 

 identified to the lowest taxon and enumerated. Wet 

 weight of each taxon was also determined. 



Diet composition was characterized by percent of 

 total number of food items (%N), percent of total 

 diet by weight (%VF), and frequency of occurrence 

 in nonempty stomachs (FO). An index of relative im- 

 portance (IRI) was then derived from these values 

 IRI = FO (%N + %W) (Pinkas et al. 1971). 



The data were further stratified by sex, time of 



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124' 



5 Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Figure 1.— Stations where Pacific hake stomachs were taken dur- 

 ing 1983 NMFS West Coast Groundfish Survey; 100 and 200 m 

 isobaths are also shown. 



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