FOOD OF ALBACORE IN THE PACIFIC 



465 



100 

 80 

 60 

 40 



GILL NET 



CRUSTACEANS SQUID 



OTHER 

 MOLLUSCS 



FISH 



OTHER 

 FOOD 



FIGURE 6. — Frequency of occurrence of major food groups 

 in 349 albacore according to method of capture. 



Bramidae, Stemoptychidae, Paralepididae, My- 

 ct-ophidae, Scomberesocidae, Chiasmodontidae, 

 and Alepisauridae. Saury dominated in troll- 

 and gill net -caught albacore, with myctophids 

 next in frequency of occurrence. Squid were well 

 represented in the albacore captured by all three 

 methods. 



Among the crustaceans, the main difference was 

 the lack of stomatopods in the diet of troll- and 

 gill net-caught albacore. This reflects the scarcity 

 of stomatopods in the offshore plankton in the 

 temperate Nortli Pacific. For example, during 

 Hu-gh M. Smith cruise 30, which covered the area 

 north of Hawaii to approximately latitude 50" 

 N., stomatopods occurred in only 2 of 124 plankton 

 samples collected. These two samples were col- 

 lected at 25° N. and 30° N., on the southern por- 

 tion of the cruise. 



VARIATION IN FOOD WITH LATITUDE AND 

 LONGITUDE 



Latitudinal variations in the volume of the food 

 of longline-captured albacore from tlie equatorial 

 Pacific are compared with variations in zooplank- 

 ton, larger trawl-caught organisms, and tlie catch 

 rate of albacore in figure 7. 



ZOOPLANKTON (A) 



159) 



FORAGE ORGANISMS (B) 



(21) 



1 





STOMACH VOLUME (C) 



(50) 



1(18) (Ig) 



At 



I6°S.-5°S. 5»S.-I°30'S. r30'a-l°3ON. I■'30'^-5•'N. 



LATTTUDE 



FiGUBE 7. — Latitudinal variation.s in the equatorial Pa- 

 cific of (A) zooplankton, (B) forage organi.sms, (C) 

 volume of stomach contents iier pound body weight 

 of 142 longline-caught albacore, and (D) albacore 

 catch rates. (Numbers in parentheses refer to sam- 

 ple sizes or (D) number of longline fishing stations.) 

 Zooplankton data from King and Hida, 1957. Forage 

 organism data from King and Iversen, 1962. (Catch 

 rate data from the records of the Bureau of Commer- 

 cial Fisheries Biological Laboratory, Honolulu.) 



The method used by King and Hida (1957), 

 presenting data on zooplankton abundance in the 

 equatorial Pacific according to the subdivisions of 

 the equatorial current system, has been followed in 

 constnicting figure 7. In tliis report the subdivi- 

 sions utilized are: (1) a zone of convergence in the 



