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Figure 27. --Yellowfin fishing conditions by 

 months (25° to 30° N. , 130° 

 to 140° E.) 



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Figure 28. --Yeliowfin fishing conciitiona by 

 months (19° to 24° N. , 140° to 

 155° E.) 



situation existing in October, the form of 

 this curve tencis to coincide with that for 

 Palau waters. It also shows a tendency to 

 agree quite well with the nnonthly fishing 

 conditions for bigeye tuna described above. 



Figure 29 shows the monthly 

 fishing conditions for yellowfin tuna in the 

 area east of the Ogasawara Islands and 

 connecting with the northern part of the area 

 treated in the preceding figure. This figure 

 shows the maxinnum catch rate in this area 

 to occur in July with the secondary peak in 

 Novennber. The low points in the curve ap- 

 pear in Januajy and October, with the 

 January minimum being the lowest. 



If this is compared with the 

 preceding figure, the conspicuous peak which 

 appeared in May, here appears in July, a 

 difference of 2 nnonths. The preceding sea 

 area showed a peak in December, but in this 

 sea area it appears 1 month earlier in 

 November. The low points on the curve oc- 

 curred in February and July in the preceding 

 area, while in this area they are in January 

 and October. The winter low is 1 month 

 earlier in this area, while the summer low 

 is about 3 months later. Although there are 

 these seasonal differences between 

 the two areas, the forms of the 

 curves as a whole are in agreement; 

 and they appear to have something 

 in common with the curves for the 

 bigeye tuna in the low latitude sea 

 areas. As for the seasonail lag 

 between the two areas, it may be 

 thought that there is a lag in the 

 time of the north-south migrations 

 of the schools. 



It is impossible to reach 

 amy definite decision on the basis 

 of the ajnount of data available, 

 however, it is thought that a differ- 

 ence in the migrational pattern of 

 yellowfin tuna to the east and west 

 of the line formed by the Izu Islands, 

 the Ogasawara Islands, the Mariana 

 Islands, and the Carolines can be 

 detected. We cannot thoroughly 

 examine the presence or absence 

 of such a difference because of the 

 scarcity and uneven distribution of 

 the data. 



MONTH 

 STATIONS 



HOOKS 



152 



