On the Age of Yellowfin Tuna trom Palau Watera 



by 

 Kenzo Ikebe, Technician 



[from South Sea Fishery News, Vol.3, No, 10. December 15, 1939] 



Data on the lengths and weights of fish are of great value as reference 

 materials for the study of the grounds where the fish were taken. For this rea- 

 son the author took measurements of 11 yellowfin tuna taken on the long lines of 

 the Hakuo ITaru November U west of Palau (position of fishing grounds, 7® 10' N, 

 134° 3' E). 



The following table shows the results of measurements of the body length, 

 total length, body depth, body width, and weight as well as the condition factor 



-2 X 1,000) calculated according to the method published by Mr. Kinosuke 



l3 Kimura of the Central Fisheries Experiment Station. 



( 



The author then calculated the condition factors for two sets of data which 

 had been collected aboard the Hakuo Maru before he reported for duty at this 

 Station. These data are segregated b7 sexes and one set waa taken from 11 yel- 

 lowfin caught east of Palau on May 11 of this year (position of fishing ground, 

 7° 18« N, 134° 42' E) while the other set represents 14 yellowfin taken May 14 

 at 7° 21" N, 134° 44' E„ These data are given in the following tables. 



According to a study by Dr. Hiroakl Aikawa entitled "The Age of Fishes and 

 Changes in Their Length and Weight" which was published in Volume 4, Number 11, 

 of Marine Fisheries CKaiyo Gyogyo], it is possible to find the age of « j^Jf^ ^ 

 comparing its wei^t and length with the figures supplied in a table. (This 

 study originated in the relationship between the length and weight and the verte- 

 bral bones of fishes, and was published in Volume 7, Number 2, of the Bi^ll?^ii^ 

 of the Jafyaneae Society of Scientific Fisheries.) 



The author was greatly impressed and interested when he learned of the ex- 

 istence of such an extremely valuable thing as a ready reference table on the 

 age of fish, and decided to try to compare the results of these three sets of 



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