DURBIN ET AL.: STOMACH CONTENTS OF HAKE AND COD 



COD, <30 cm 



o 

 u 



SPRING 



FALL 

 4.2 





2 



3.9 



CO 



t- 2.0-1 



COD, >30 cm 



SPRING 



FALL 



1.5- 



I | Other prey 

 \TA Fish prey 



ZdJZ 



7, 



•jeTxlub: 



24 06 12 18 24 



24 06 12 18 24 



TIME, hours 



FIGURE 4. — Diel changes in "total stomach content weight," "fish 

 prey," and "other prey ' in the stomachs of small and large Atlantic 

 cod during spring and fall. 



and 10.2' v duringfall. Among small cod, the respective 

 percentages were 10.6 and 14.7%. 



Daily Ration 



In order to describe the average feeding behavior of 

 all fish in the samples, the mean stomach content 

 weights, which included fish with empty stomachs, 

 were used to estimate the mean feeding rate for each 

 3-h period during the day (Tables 6, 7). Ingestion es- 

 timates fluctuated considerably, and negative as well 

 as positive values occurred. The negative ingestion 

 estimates resulted when the decline in amount of 

 food in the stomach from one period to the next was 

 greater than predicted from the evacuation rate used 

 in the calculation. Daily rations were obtained by 

 summing the amount of food ingested during each 3- 

 h period. 



With the exception of small silver hake in the fall, 

 the daily ration estimates for the two species were not 

 greatly different: small hake, 1.82 and 4.657c BW 

 during spring and fall, respectively; large hake, 2.40 

 and 1.927; and large Atlantic cod 1.42 and 1.667r 

 BW (Tables 6, 7). Overall, hake consumed more than 

 large cod; the daily ration of small cod was not es- 

 timated because of the small sample size. The daily 

 ration of small hake and large cod was higher, and of 

 large hake was lower, during the fall than during 



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 o 

 < 



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0- 



100 



80 



60- 



40- 



100 



80 



UJ 60 

 O 



tc 



UJ 40 

 CL 



20- 



24 



SILVER HAKE 



SPRING 

 <20cm 



SPRING 

 >20 cm 



FAL L 



06 



18 24 



TIME, 



24 06 



h r s 



18 



CO 



I 

 o 

 < 



o 



I- 

 co 



UJ 



100 -, 



80 -I 



60 - 



40- 



20 



0- 



100 



UJ 60-| 



o 

 rr 



UJ 40- 

 0- 



20 



COD 



SPRING 

 < 30 cm 



SPRING 

 >30cm 



^=t 



FAL L 



24 06 12 18 24 24 06 



TIME, hrs. 



Figure 5. — Diel changes in the percentage of empty stomachs of silver hake and Atlantic cod collected during each 3 h time period. 



445 



