bo Position of Ocean Currents and Fishing Conditions 



Vlhen the power of the second branch of the warm current is weak or the 

 third branch of the warm current does not reach the waters off Noshappusaki, 

 the coastal stream and the second stream of the Chishima cold current reach 

 the waters off Kushiro without branchingo (See section III.,) August 1926 

 and September 1929 (no observations were made in August) are exanples of 

 this. The forlner extended from 20 miles south to Uo miles south of Kushiro, 

 the latter from 10 to UO miles south of Kushiroo The breadth of the current 

 was great and the third branch of the warm current also failed to break 

 through the line south of Kushiro, In such cases the fish vriiich migrate 

 east of Akkeshi are few, and the fishing is good at Kushiroj with many 

 large tuna. 



Off Erimosaki the third branch of the warm current (mingled with the 

 Tsugaru warm current) ordinarily extends from the station 30 miles south 

 of Erimosaki to the waters off Kushiro^ but in 1932s because of the strength 

 of the coastal stream of the cold current, the third branch of the warm 

 current did not pass the line south of Erimosaki and consequently the 

 migration of the tuna schools into the Kushiro area was blocked with the 

 result that Urakawa had good fishing while the fishing was poor at Kushiro, 



c. Strong Warm Currents and Fishing Conditions 



When the third branch of the warm current is strong off Kushiro and 

 the cold current is pushed back, there is sometimes rather good fishing. 

 Examples of this situation are August 192$ and September 1928, and in 

 both these years small tuna were remarkably mmierous. 



Considering the fishing situation for every year, in most cases the 

 fishing is good in the latter part of July, This is because the tuna 

 schools are in the area where the cold and warm currents are in contact, 

 the schools are not scattered, and their position is clearo 



dc Number of Sunspots and Fishing Conditions 



r3) 



MTo Yokichi Kurita has investigated the relation between the number 

 of sunspots and the tuna fishery of Mie Prefecture, and has reported that 

 when the sunspots are at their minimum the fishing is good, while it is 

 poor when they are at their maximum. The Assistant Technician of this 

 Station has used the statistics of the Hokkaido Government to con^jare the 

 catch of tuna for all Hokkaido with the .number of sunspots and has reported 

 that there is a positive correlationo ^^' This means that the tuna catch 

 in southern Japan and the catch in the North are opposite to each other. 

 When the total catch at Kushiro and the number of sunspots are con^jared, 

 they are positively correlated. However, taking into consideration the 

 fact that the number of boats engaged in the tuna fishery has increased 

 from year to year because of the recent rise of the fishery, and that 



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