abundant in the coastal water region, with their fishing grounds stretching to the southern Kurile 

 Islands. Off Kinkazan, spearfishes, principally the striped marlin, are taken, many broadbill 

 are caught everywhere beyond 200 miles from the coast, and at times there are great runs of 

 albacore. The bigeye tuna generally appear to show a trend to greater abundance the farther one 

 gets off shore, but neither they nor the yellowfin have any very important significance. To the 

 northward of the broadbill grounds there are shark fishing grounds, principjllly for Isurus nasus , 

 and considerable amounts of these fish are taken. 



Considered seasonally, the season for black tuna begins in early summer axid the 

 fishing grounds gradually shift from the south of the sea area to the north, with catches made 

 until late autumn. Striped marlin are nnost nunaerous in midsummer, with some catches until 

 early fall, after which hcirdly any fish are taken. Broadbill fishing is active from early autumn 

 to early winter with the fishing grounds gradually extending from north to south. About the time 

 broadbill fishing comes to an end, that is around December, large schools of albacore occa- 

 sionally appear. The shark Isurus nasua is most abundant in April ajid September, with two fish- 

 ing seasons during the yeeir. 



Of the species mentioned in the foregoing, black tuna in recent years have hardly 

 been taken at all, consequently the fishery for this species has completely died out. 



V) 



30 



20 - 



10 - 



O 



tn 

 "o 

 o 

 o 



o" 



- 



"1 — I — r 



"1 — r 



"1 — r 



-o NUMBER OF FISH 

 -a AVERAGE WEIGHT 



"1 — r 



"I — r 



- 40 



60 



XOD 

 O II 



20 Lj; 



$5 



1940 



Figure 14. --Annual landings of black tun^ at 

 Kushiro 



If this graph is compared with a similar curve for Aburatsu (see figure 11), there is 

 agreement in the peaks which appeared in 1931, but the fluctuations in the catch thereafter are 

 very different. At Aburatsu the catch from 1933 to 1939 did not vary greatly, and the fishing 

 situation was shown to be compauratively stable. However, at Kushiro after the peak in 1931 the 

 catch fell off steeply with no recoveries. A conspicuous peak in the catch for 1940 was shown for 

 Aburatsu, but no tendency toward an increase appeared at Kushiro. 



A certain degree of agreement can be detected in the average body weight curves in 

 that a trend toward increase from year to year is clearly shown. However, the average weights 

 at Aburatsu were generally about 80 pounds greater than those for Kushiro. 



If we consider the relatedness of the fishing conditions and the schools of fish in this 

 sea area and in the waters around Tanegashima, there appear to be at the same time elements 

 which show a relationship between the two arecis and elements which deny this relationship. Con- 

 sequently, with only the data recorded above, it is difficult to either deny or affirm the related- 

 ness of these two sea areas. 



112 



