For comparison, in the waters south of the Ogasawara Islands the highest catch rate 

 appeared in August, 1 month later than at Takao. However, it is probably safe to consider that 

 in the sea area centered around 20 N. the density of distribution of black marlin reaches its 

 height around July and August. 



Records of the weight of the fish taken are lacking for other sea areas so we do not 

 know the body weight composition of the catch, but at Teikao there was a conspicuous difference 

 in the weight composition as between the fish tjiken in the summer and those taken in the winter. 

 Fish caught in the sumnner were generally small, with the mode appearing at 40 to 50 kilograms 

 while in November-December it appeared at 60 to 70 kilograms and in January at 80 to 90 kilo- 

 grams. The weight composition of the fish taken from March to September showed two nnodes, 

 one at 40 to 60 kilograms and one at 100 to 140 kilograms, (see Nakamura, Journal of the 

 Formosan Natural History Society, Vol. 34). 



Table 116 shows fishing conditions at Takao by months for striped marlin. The data 

 are from the same source as those in table 115. 



The number of fish taken was not very great, but the largest number appeared in 

 May with the low of the year in September and a second peak appearing in December. This may 

 be compared with the area south of the Ogasawara Islands, where the peak catch rate appeared 

 in May. Thus, although there are points of disagreement between the rises and falls in the 

 catch rate and the increase and decrease in the number of fish landed in each nnonth at Takao, the 

 peak months are the same in both cases and we can probably consider that, just as in the case of 

 the black marlin, dense schools appear at the same season on approximately the same latitudes 

 without regard to longitude, 



o o 



In the following figures the adjacent area on the north between 25 and 30 N. has been 



divided into three sections of 140° to 150 E. , 130° to 140° E. , 120° to 130° E. and the fishing 

 conditions by months have been shown for each of the sections. 



o o o 



As the figure shows black marlin are scarce in the area of 25 to 30 N. , 140 to 



150 E., but they are somewhat nnore abundant from April to August. There is an extremely 



conspicuous peak in the striped marlin catch rate in May with a value of slightly less than 4. 0. 



Thereafter the catch rate falls off steeply and from August to October hardly any fish are taken. 



In November there is again a fairly conspicuous peak. For all the spearfishes as a whole there is 



a third peak in February, but this is formed principadly of broadbill. 



Comparing this with the area south of the Ogasawajras, which adjoins this area on the 

 south (fig. 34), there is a peak in Mcirch which does not appear in this sea area but otherwise 

 although there are differences in the numericed values for the catch rates, there is good agree- 

 ment in the trend of increase and decrease in the striped nnarlin catch rates and we see no such 

 conspicuous seasonal lag as was found in the case of the yellowfin. The black marlin catch rate 

 curve in this sea area is quite irregular, and its agreement with the curve for the area south of 

 the Ogasawaras is not as striking as it was in case of the striped marlin. 



o o o o 



Fishing conditions in the Nankai sea area, 25 to 30 N. , 130 to 140 E. , are shown 



in figure 36. A thorough comparison is innpossible because of deficiencies in the data, but the 



black nnarlin catch rate curve appears to be quite conspicuously different from those for the sea 



area east of the Izu and Ogasawara islands. In this region there is a fairly high catch rate in 



January, decreasing thereafter gradually to Mairch and with almost no catch in April, followed by 



a second increase forming a rather conspicuous peak in June. For the striped marlin there is a 



conspicuous peak in May and a fairly high catch rate in June, but in July they decrease rapidly. 



The peak which was seen in the area east of the Izu cind Ogasawara Islands in November does not 



seem to appear here. In the Hyuga Nada region, which adjoins this sea area to the north, striped 



marlin are abundant around April to June, jind quite a few axe taken by the harpoon fishery. 



161 



