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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



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TROLL CAUGHT 



POLE -AND- LINE CAUGHT 



LONGLINE CAUGHT 



JAN 



FEB 



MAR 



APR 



SEP 



OCT 



NOV 



DEC 



Figure 2. — Distribution of yellowfin stomach collections, by month and by method of capture, 



February 1950 to September 1951. 



it was not distributed over the months of the year 

 for each fishing method as well as desired. Figure 

 2 indicates, for each method of capture and for 

 all methods combined, the number of stomachs 

 obtained during each month, the years 1950 and 

 1951 combined. 



METHODS 



COLLECTION OF MATERIALS 



In the field, the stomach was removed as soon 

 as possible after the fish was captured, placed with 

 any regurgitated material in an unbleached muslin 

 bag, and preserved in 10-percent formalin. A 

 label bearing the date, the locality, the method, 

 depth, and time of capture, the species, fork length, 

 bait used, name of observer, and vessel, was 

 placed with each stomach. 



The stomach was removed by one of the follow- 

 ing methods: 



(1) The abdominal cavity was opened by a 

 longitudinal midventral incision, the small in- 

 testine severed posterior to the pyloric valve, and 

 the stomach freed by cutting through the muscular 

 esophagus. 



(2) The gill membrane was slit along the line 

 of attachment with the cleithrum, posterior to the 

 fourth gill arch, the viscera pulled out, and the 

 stomach removed by cutting through the small 

 intestine and esophagus. 



IDENTIFICATION OF STOMACH CONTENTS 



In the laboratory, the stomachs were leached 

 in fresh water for a period of 12 to 24 hours to 

 remove excess formalin. All of the contents were 

 carefully removed and separated into groups. 



