summer striped maurlin of 50 to 100 pounds predominate in the early part of the season. 

 Thereafter the black marlin increase auid at the peak of the fishing season, rather small black 

 mairlin of 80 to 160 pounds are most numerous. Many sharks, principally great blue sharks, 

 are taken throughout the year, and at times they make up more than half the total catch. 



(c) East of 150 E. 



(20° to 50° N. ) 



The only land in this area is Marcus Island at 24 30' N. , 154 E. , and oceanographic 

 conditions are comparatively uniform. The northern part of the area includes a patrt of the 

 albacore grounds which extend on to the north and east and is an excellent ground for this species. 

 The southern pajt, except for the vicinity of Marcus Isljmd and on to the eastward, is almost a 

 virgin fishing ground with few survey data, and its significance and value as a fishing ground aure 

 little known. The vicinity of Marcus Island is a fishing ground principally for spearfishes and 

 yellowfin tuna, and the fishing situation there is in general sinnilar to that of the Ogasawara 

 Islands area. 



The following table summarizes the survey data for this sea area. 



Table 60. --Fishing conditions between 150 and 180 

 E. (20 to 30° N. ) 



The overall catch rate is slightly over 4.5. Fishing conditions north and south of 25 

 N. are very different, with spearfishes most abundant in the south followed by bigeye tuna and 

 yellowfin. North of 25 N. albacore make up the majority of the catch. No black tuna have been 

 taken in the southern part of the area, but some very scattered catches have been made in the 

 northern part. Yellowfin are much scarcer in the northern part them in the southern part, there 

 is no great difference in the abundance of bigeye, and albacore are extremely scarce in the 

 southern portion, although they make up more than half of the catch in the northern part. The 

 spearfishes are much less abundant in the northern part of this area. 



If this is compared with the situation in the waters of the Ogasawara, Volcano, and 

 Mariana islands described earlier, there are hardly any differences except that in the southern 

 part the yellowfin and bigeye are quite a bit more abundant in this region. In the northern portion 

 this area shows somewhat of a decrease in the nunnber of yellowfin sind spearfishes and a marked 

 increase in bigeye. The albacore catch rate is also a little less than 1.0 per hundred higher 

 in this sea area. It is a characteristic of this sea area that bigeyed tuna catch rates show a 

 rather marked overall increase. However, it is thought that the reason for this is mainly the un- 

 even seasonal distribution of the data. 



Seasonal changes in fishing conditions cannot be determined accurately because the 

 data are almost entirely limited to the winter. Changes in the fishing conditions from month to 

 month for that part of the year for which data are available are presented in tables 6l and 62. 



94 



