HAWAIIAN GROWTH CURVES 



JAPANESE MODES i 



JAPANESE FISHING 



OIJ OIJ OIJ OIJ DIJ DIJ OIJ OjJ 



l-^ 1 9 48 ---I--- 1 9 4 9 ---[--- 1 9 5 ---(--- 1 9 5 I -4^ 1 9 5 2 --+-- 1 9 5 3 --4-^ 1 9 5 4 --^ 



Figure 15. --Comparison of Hawaiian and Japanese bigeye 

 tuna "growth lines" using data from the Japanese North 

 Pacific fishery taken from Kamimura and Honma (1953) 

 and Nakamura et al. (1953). 



Nakamura et al. (1953) propose and Kamimura and Honma 

 (1953) discuss at length three hypotheses to explain the "biennial 

 frequency" which they observe in the Japanese North Pacific fishery. 

 These hypotheses are: 



"i. Difference in annual propagation; 

 ii. Difference in annual growth rate; 

 iii. Difference in annual course of migration. " 



Kanninnura and Honma are unable to decide which hypothesis best fits 

 this phenomenon. They feel that perhaps that of differences in annual 

 propagation (i) is the most reliable and that an annual migratory 

 pattern (iii) may be accepted as a reasonable hypothesis "provided 

 that the fish should take the same migratory route every two years. " 



Unfortunately even with the added knowledge that this cycle 

 occurs in the Hawaiian fishery there is still insufficient information on 

 the biology of the species to permit a definitive explanation. Sonne sort 

 of a migratory pattern would seem to best satisfy the relationship of 

 the sizes of bigeye in the two areas. There is considerable circum- 

 stantial evidence to indicate that this species may be moving about 

 over a vast expanse of the Pacific, Spawning apparently takes place 

 only over a large area near the Equator, from about 150 E. to 140 W. 

 longitude, and mature or nearly mature females are found there at all 

 times of the year (Kikawa 1953, Yuen 1955). Neither of these authors 

 could find evidence of a spawning area farther to the north. If the 



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