Table 65 shows the oceanographic conditions in this area based on considerable data. 

 The water color is generally II or III on Forel's scale, and transparencies atre low, about 20 

 meters. 



The extreme western part of this area in the vicinity of Tanegjishima is famous as a 

 black tuna fishing ground, but in recent years no fish have been taken at all 3uid no boats have 

 been operating there. The fishing season was limited to the winter, beginning around December 

 and with the peak of the season in January and February. The main base for this fishery was the 

 port of Aburatsu in Miyazaki Prefecture, and the amount of lajidings and changes in the size of 

 fish for a number of years at that port are shown in figure 12. 



X 



if) 



o 

 o 

 o 



80 



- 60 



< 



40 i 



UJ 

 20 $ 



1930 



1935 

 YEAR 



1940 



1945 



Figure 12, --Annual changes in black tuna landings 

 and average weight at Aburatsu 



Table 65, — Oceanographic conditions in the vicinity 

 of 32° N. , 133° 30' E. 



It is clear from the figure that a rapid increase in the number of black tuna landed at 

 Aburatsu began in the early years of the Showa Era, the peak being reached in 1931 with landings 

 of about 43, 000 fish. From 1932 through 1933 there was a gradual decline, and then the landings 

 continued without much chamge at around 20 to 30 thouscind fish fronn 1933 to 1939. There was a 

 fairly marked increase to 35, 000 fish in 1940. From 1941 on the catch fell off steeply, and from 

 1945 to the present there has been hardly any catch at all. 



As for the size of the fish, the average weight in 1927 and 1928 was around 165 

 pounds, in 1929 this suddenly increased to about 396 pounds. From 1930 to around 1938 the 

 average weight fluctuated between 331 zmd 410 pounds. From 1939 on the fish increased in size 

 from year to year and after 1942 the average was about 496 pounds. 



98 



