FISHERY BULLETIN: VOL. 82, NO. 2 



tially lower during these periods. Collections 

 taken around late afternoon had equal amounts 

 of fishes and euphausiids, while those taken at 

 night had high occurrences and biomass of cepha- 

 lopods (mostly Loligo opalescens) and gelatinous 

 zooplankton. 



The mean fullness score, mean digestion score, 

 mean weight ratio (equal to the weight of stomach 

 contents divided by weight of fish), and the per- 

 centage of empty stomachs were plotted for each 

 adjusted collection time for both species. Sebastes 

 pinniger had a distinct periodicity in its feeding 

 cycle (Fig. 6). Peak periods of feeding intensity 

 occurred midday and shortly after dusk. One col- 

 lection (eight stomachs) taken at 0400 h had low 

 values for fullness score and weight ratio but 

 average values for digestion score and percentage 

 of empty stomachs. The fullness and digestion 

 scores (Fig. 6A) follow each other fairly well 

 except that the midday digestion peak was several 



hours later than the fullness peak. A very distinct 

 peak in the weight ratio at 1200 h and a smaller 

 one shortly after dusk are evident (Fig. 6B). 



Sebastes flavidus also appears to show a diel 

 periodicity in its feeding pattern (Fig. 7). The 

 fullness and digestion scores track each other very 

 closely and show distinct peaks of feeding inten- 

 sity around noon and shortly after dusk, although 

 the number of samples in the latter period was 

 limited (Fig. 7A). The actual mean weight ratio 

 showed similar trends, but the noon peak is 

 somewhat obscured (Fig. 7B). The percentage of 

 empty stomachs was highest in the morning and 

 remained low through the remainder of the day 

 unlike that found for S. pinniger. 



A high degree of variability in the mean weight 

 ratio was found several times, especially during 

 periods of peak feeding when both totally dis- 

 tended and almost empty stomachs were often 

 found together. The differences in the weight 



ui 



o 5 

 co 



< 2 



(A) 



• • MEAN FULLNESS SCORE 



0---0 MEAN DIGESTION SCORE 



SAMPLE 

 SIZE 



12 16 10 30 45 34 10 39 46 33 24 40 21 



SR 



ss 



10 



rr 



I 



Ld 

 ^ 4 



< 

 Id 



(B) 



WT STOM CONT (g) / WT FISH (kg) 



■O PERCENT EMPTY STOMACHS 



100 



CO 



80 5 



-60 



40 



co 



2 



LlI 

 20 O 



Ld 

 0_ 



0400 0800 



1200 





 1600 2000 2400 



SR 



SS 



TIME (hours) 



a. 

 o 

 o 

 co 



< 



Ld 



• • MEAN FULLNESS SCORE 



0---0 MEAN DIGESTION SCORE 



10 



o 



< 

 q: 



t- 

 I 



Ld 



■z. 







SAMPLE SIZE 17 16 2028 22 12 14 23 46 II 43 10 2 



~r 



-t- 



SR 



SS 



• • WT STOM CONT. (g) / 



WT FISH (kg) 



0----0 PERCENT EMPTY 

 STOMACHS 



(B) 



1 s /-Vr. 

 / 1 •, »i 



1 A > < 

 ^-r-6-cJ- 



-6-0- 



100 



CO 



X 



u 



< 



o 



(- 

 co 



60 >- 



80 



40 



20 









0400 0800 1200 1600 2000 2400 



SR SS 



TIME (hours) 



FIGURE 6. — Feeding intensity indices for Sebastes pinniger at 

 adjusted times of the day. See text for explanation of indices. 



FIGURE 7. — Feeding intensity indices for Sebastes flavidus at 

 adjusted times of the day. See text for explanation of indices. 



284 



