Figure 15. — Albacore fishing conditions 

 in each month (0 to 5 N. , 

 150° to 160° E.) 



Figure 16 shows 

 fishing conciitions in the south- 

 ern part of the Ogasawara Is- 

 lands (20° to 25° N. , 140° to 

 150 E.). Because of the scar- 

 city of data, account must be 

 taken of the error introduced by 

 the operation of fluctuations in 

 fishing conditions on the catch 

 rate. However, the trend of the 

 curve agrees well with that for 

 the area closer to the Equator 

 and the highest catch rate seenns 

 to occur in September. 



The changes from 

 month to month in albacore fish- 

 ing conditions farther to the 

 ° o o 



north in the area 30 to 35 N. , 



140 to 150 E. have already 

 been shown in the section on the 

 waters east of the Izu Islands, 

 but for the convenience of the 

 reader, these facts are plotted 

 in the following graph. 



6~- 



liJ 



(- 

 < 

 tr 



X 



o 



\- 

 < 

 o 



The data are in- 

 adequate for many parts of the 

 curve, particularly in September 

 where data are completely lack- 

 ing. When this graph is com- 

 pared with the two previously 

 presented, we not only see a re- 

 markable increase in the qatch 

 rate itself but a complete change 

 in the seasonal pattern of fish- 

 ing. The catch rate rises steep- 

 ly from November to January 

 until it attciins a figure of about 

 6. 0. In February it drops some- 

 what, but is still remarkably 

 high. From March on it falls 

 off steeply and during the 

 summer there is hardly any 

 catch. A great deal of attention 

 should probably be paid to the 

 difference between these areas 

 in any consideration of the dis- 

 tributions and migrations of the 

 albacore. As was stated earlier, 

 the albacore is densely distributed in the area of the Kuroshio and the North Pacific Current, the 

 boundary of its distribution being known to be the subtropical convergence. Not only is there this 

 remarkable change in fishing conditions as we pass the boundary of the subtropical convergence, 

 but there is also a very marked change in the size of the fish. If we compare fish taken during 

 the winter, we find that those caught south of the subtropical convergence are for the most part a 

 great deal larger thaui those taken to the north of it. 



MONTH 

 STATIONS 



HOOKS 



Figure 16. 



--Albacore fishing conditions 

 o o 



in each nncinth (20 to 25 N. 



140° to 150° E.) 



142 



