Ignoring local variations in the fishing conditions, table 73 shows the fishing conditions 

 by months for the whole sea area. There are very few data for the summer, so seasonal 

 changes in fishing conditions are not clear, but within the scope of the table the fluctuations are 

 approximately as follows. Catches of black tuna are recorded only for the months of January, 

 February, and April. A few yellowfin are taken in each month throughout the year, and they 

 appear to become somewhat more abundsmt around July and August. Highest catch rates for 

 bigeye tuna appear in April, and they are generally abundant in December and January, Hardly 

 any albacore cire taJten in the summer, the first catches being made in November with a rapid 

 increase to January, which has the highest catch rate of 5.9. In February the catch rate drops 

 sonnewhat fronn January, but it is still slightly over 5. 0. From March on the catch rate falls off 

 steeply. The spearfishes show a peak in their catch rate from June through July. In the winter 

 catch the broadbill is most important; striped marlin and black marlin aire most numerous in the 

 summer. 



Table 73. --Monthly fishing conditions (sea area east of 

 the Izu Islands) 



Table 74 shows the seasonal and local distribution of the data. 



As is shown in table 73, the greater part of the catch in the summer is spearfishes. 

 It is clear from table 74 that the area from which the spearfishes are tjiken during the summer is 

 restricted to the western part of the sea area, that is the vicinity of the Izu Isljinds, the situation 

 in the off-shore waters being unclear because of the complete lack of data. 



As for the winter season, when albacore are the main element in the catch, there are 

 approximately unifornn catch rates throughout the whole sea area in February, somewhat higher 

 values being shown only for the section from 146 to 148 E. In December cind January there are 

 large local variations in the catch rates, and these variations show no definite trend. In March 

 the catch rate is slightly over 4,0 in the extreme western section, but elsewhere in the more off- 

 shore waters the catch rates genercilly go down steeply and the significance of the area as a fish- 

 ing ground is diminished. 



If fishing conditions in this area are compared with those in the Nankai sea area 

 adjacent on the west: 



1, The catch of black tuna is nnuch less in this sea area, 



2. The catch of albacore is much greater in this area. 



105 



