latitude. The changes in the albacore catch rates in this area from March 

 to July are as follows. 



In March in the areas adjacent to the south side of the North Pacific 

 fishing ground the catch rates are high, and although the situation is not 

 quite clear in April, from May to July the catch rates are also high from 

 10 N. to 20 N. The fact that in April the catch rates appear to be lower 

 than in the preceding and following months is thought to be due to the scar- 

 city of data for the vicinity of 20 N. In actuality, judging from the small 

 amount of data we have, the catch rates in the vicinity of 20 N. appear to 

 be higher than in the southern zone. Consequently, these large albacore 

 are thought to have split off from the North Pacific fishing ground, broken 

 through the Subtropical Convergence to the south, and continued on to the 

 southward. 



In fishing in the areas of middle latitudes for striped marlin and 

 black marlin, a few albacore are always taken, and even from August on, 

 although the catch rates drop somewhat, the fish are scattered over a 

 broad area of the South Seas. They are so scarce as to be almost without 

 innportance as an objective of the fishery, but they are thought to be impor- 

 tant from the point of view of the life history of the species. Although the 

 medium- and small-sized albacore which appear on the North Pacific fish- 

 ing ground never cross the Subtropical Convergence, these large albacore 

 do cross the Convergence to the southward. As will be noted later in the 

 section for June, the gonads of these albacore are fairly ripe, and they are 

 thought to bear a deep relationship to the spawning of the species. Conse- 

 quently, these fish are extremely important, both as a link between the 

 albacore north and south of the Subtropical Convergence, and as an indi- 

 cation of the spawning habits of the albacore. 



Hasegawa — has postulated that the albacore of the area from the 

 Ogasawaras to Uracas Island are a separate stock from those which migrate 

 into Japanese coastal waters. But the albacore in this sea area, as stated 

 above, are large fish which have continued southward through the Subtropical 

 Convergence to appear in this sea area after the southward movement of alba- 

 core on the North Pacific ground has ceased. It cannot definitely be asserted 

 that all of the albacore occurring on the south side of the Subtropical Conver- 

 gence originated in the North Pacific fishing ground, but it is a fact, at any 

 rate, that they receive some recruitment from the North Pacific ground. 



11/ 



— Hasegawa, Kinei. 1938. On the report of albacore investiga- 

 tions. In Oceanic Fisheries (Kaiyo Gyogyo) No. 20. 



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