total spearfish catch. However, data are almost entirely concentrated in the period from 

 September to November, so it is impossible to make any concrete observations on fishing con- 

 ditions at other seasons. 



Table 85. --Fishing conditions by nnonths 



If we compare the situation north and south of the line of 40 N, , it appears that the 

 fishing season in the northern section begins and ends fronn 1 to 2 nnonths ecirlier than in the 

 southern section. It can also be seen that the number of species taken in the northern section is 

 less than in the south. 



If we compare fishing conditions in general in the northeastern sea area with those 

 in the area east of the Izu Islands adjacent on the south: 



1. More black tuna are taken in the northeastern sea area, the peeik fishing season 

 for this species is earlier the farther north one goes, and the season is later and longer to the 

 south. 



2. Yellowfin are extremely scarce in both sea areas, but they clearly tend to 

 decrease as one goes north. 



3. Bigeye tuna are taken with a rather even geographical distribution in the winter 

 season, but the^ are generally scarce in the summer and decrease as one goes to the northward, 

 hardly any being taken in the extreme northern part of the area. 



4. The peak fishing season for albacore is cleajly from December to February, and 

 hardly any are taken at other seasons. In both sea areas the catch increases toward the center 

 of the Pacific Ocean. 



5. The total catch rate for all species of spearfishes does not differ greatly between 

 the two areas. In general, striped mcirlin and black marlin are most abundant in the summer 

 season, with broadbill increasing in nunnbers from October on. Striped marlin and black nnarlin 

 show a tendency to increase in numbers in early summer in the southern part of the area, with 



a second increase in the catch rates from late autunnn to early winter. In the extreme northern 

 part of the area they increase in numbers from late summer to early fall. These phenomena are 

 considered to show a north-south migration of these species. 



6. Sharks are rather abundant in both areas, 

 one in the winter and one in the late summer. 



There are two peak fishing seasons. 



Since this sea area is at the northern limits of the tuna and spearfish longlining 

 grounds, the fishing seasons are more clearly marked than in warmer seas, and there are cons- 

 picuous variations in oceanographic conditions from year to year, accompanied by marked 

 fluctuations in fishing conditions. 



117 



