FISHERY BULLETIN: VOL. 84, NO. 4 



Table 2.— Summary of stomach contents of Merluccius productus collected during the 1983 NMFS Pacific Coast Groundfish Survey. 



T = <0.1%. 



30-34 cm 



35-39 cm 



40-44 cm 



45-49 cm 



50-54 cm 



>55 cm 



Prey category 



FO 1 %N 2 %W 3 FO %N %W FO %N %W FO %N %W FO %N %W FO %N %W 



Euphausiacea 



Thysanoessa spinifera — — — 14.9 15.0 14.7 27.5 10.6 9.4 32.5 79.6 17.2 52.4 65.1 14.9 61.9 62.3 6.4 



Euphausia pacifica 25.0 16.7 17.1 56.4 73.7 72.7 68.1 78.5 70.8 10.4 9.0 2.2 19.5 18.7 3.9 33.3 23.4 1.3 



Unidentified 100.0 83.3 82.9 33.0 10.4 6.2 33.3 10.3 10.7 31.2 9.2 2.5 35.4 12.4 1.9 19.0 9.0 0.2 



Decapoda 



Pandalus jordani — — — 1.1 T 0.2 — — — 1.3 0.1 0.1 — — — 19.0 2.3 4.9 



Sergestes similis — — — 2.1 0.7 2.9 5.8 0.3 2.5 — — — — — — — — — 



Pasiphaea pacifica — — — — — — 1.5 T 2.0 — — — — — — 14.3 1.5 0.4 



Crangon sp. — — — — — — — — — 2.6 0.1 0.2 4.9 1.1 12.0 — — — 



Callianassa sp. ___ ______ 11.7 o.7 13.4 8.5 1.1 14.5 — — — 



Osteichthyes 



Engraulis mordax — — — — — — — — — 1.3 0.1 1.5 2.4 0.3 2.7 — — — 



Clupea harengus — — — — — — 2.9 0.1 3.8 3.9 0.2 34.7 3.7 0.2 28.4 — — — 



Thaleichthys pacificus — — — — — — 1.4 T 0.6 9.1 0.4 23.0 1.2 0.1 T — — — 



Osmeridae — — — — — — — — — 1.3 0.1 T 1.2 0.1 2.8 — — — 



Gadidae — — — ———— — — 1.3 0.1 1.2 2.4 0.2 2.4 4.8 0.2 83.6 



Pleuronectidae — — — — — — — — — 1.3 0.2 0.1 2.4 0.2 14.5 9.5 0.6 3.4 



Agonidae ___ ___ ___ ___ 1.2 0.1 0.4 — — — 



Myctophidae ___ 0.8 T 1.5 — — —— — —— — —— — _ 



Unidentified — — — 5.3 0.2 1.8 5.8 0.2 0.3 9.1 0.4 3.6 7.3 0.5 1.8 14.3 0.6 0.1 



Number of stomachs 



(empty) 11(7) 120(26) 97(28) 118(41) 93(11) 27(6) 



Number of prey items 6 2,006 2,029 1,921 1,206 478 



Weight of stomach 



contents (g) 0.4 77.0 78.0 376.5 319.3 293.0 



1 Frequency of occurrence in non-empty stomachs. 



2 Percent of diet by number of items. 



3 Percent of diet by weight of stomach contents. 



ing animals were found in stomachs of Pacific hake 

 taken at towing stations between 8.3 and 15.6 km 

 (4.5 and 8.5 mi) offshore but not in immediate prox- 

 imity to estuaries where ghost shrimp are most 

 often found. 



Chi-square tests (Table 3) illustrate the patterns 

 in prey consumption by various stratifications of the 

 data. There was little statistical difference in 

 stomach contents of males compared with females. 

 The analysis of prey categories by depth is essen- 

 tially an inshore-offshore comparison as isobaths run 

 roughly parallel to the coastline in the study area. 

 Statistically significant differences were found in 

 depth of capture for both species of euphausiids 

 found in this study. Thysanoessa spinifera was more 

 important in the diet of fish taken close to shore 

 whereas Euphausia pacifica was important for fish 

 taken futher offshore. Eulachon, Thaleichthys pacif- 

 icus, was found in stomachs more often in shallow 

 waters than at depth. These animals, being anad- 

 romous, are often found in bays and estuaries, i.e., 

 close to shore. 



A significant difference exists in the presence of 

 the two species of euphausiids in stomachs collected 

 at different times of the day. The data collected in 

 this study show that T. spinifera were seldom found 

 in stomachs collected after 1600 h while E. pacifica 



Table 3.— Chi-square analysis of difference in stomach content 

 by prey category and various factors. 



Factor 



were often found in stomachs collected during that 

 time (Fig. 2a). 



To further examine the diel feeding pattern of 

 Pacific hake, the percent of all stomachs in each of 

 two fullness categories (<25% full; > 75% full) was 

 calculated by time of day. A three-point moving 

 average was computed for each fullness category, 

 and the resulting averages plotted (Fig. 3). There 



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