amounted to 25 million fish or 56?' of the total skipjack catch of the 

 whole country. Of this l/5 "'as landed at Kesennuna in ?,''iyagi Prefecture. 

 The present paper sets forth the results of an investigation of the 

 sizes , based on data from radio broadcasts, of these 5 million fish 

 landed at Kesennuma. 



The number of skipjack caught at Kesennuitia in the three years 1933, 

 1934., and 1935 was only about 2 million, but in 1936 it suddenly doubled. 

 Succeeding years have continued to have heavy catches of 4.. 8 - 4-. 9 million 

 fish, and this year's catch was on a level with the average of the catches 

 of the past four years. As Figure 1 shows, the fishing grounds moved 

 north from their position off the Boso provinces in the latter part of 

 June to reach their northernmost limit about 50 miles south of Etorofu !„ 

 in the r.'uriles in the last ten days of September, the fishing situation 

 being in this respect also generally comparable to the average of the 

 past fovnr years. 



Throughout the whole fishing season the smallest sized fish was 20C 

 monMe /~1 morrn e = O.1325 ounce_7 and the largest was 1,050 momme , large 

 individuals of 2 - 3 kan / 1 kan = 8.27 poimds_7, such as are taken in the 

 Satsunan and Ogasawara areas, being completely absent. 



In the last ten-daj'' period of Jurie when the first catches are made in 

 this area, fish of /^.OO - 700 momi ne are taken and their mode, as shown in 

 Figure 2, is at 450 - 500 momiie . In the first and second ten-day periods 

 of July this m^ode gradually advances to a heavier weight, and in the last 

 ten-day period of July it is at 550 - 600 rriomme. For the s--^ke of convenience 

 these m.ediun-siaed skipjack are called Group A. Frow this time on Group B 

 of fairly large fish of 750 - 8OC moiimie appear in the catch. From the middle 

 ten-day period of August on Group C consisting of small fish of 200 - 

 250 morrime appear, and from about the first ten days of September Group D 

 of medium-sized fish of 4-50 - 500 mom me corresponding to the Group A of the 

 third ten days of June appears in the catch. In all, four groups of fish 

 of different weights can be detected. In about 100 days from the last 

 ten days of June to the first ten days ox September the fish of Group ^ 

 increase in ?7eight by 200 mojrme, and Grouri B snows a similar tendency, 

 but after the last ten-day period of Septem-ber both groups stayed within 

 a fixed range and there was little change in weight. Thus it appears 

 that while the schools are moving north the fish increase in weight, while 

 after the schools turn south the gain in weight ceases. There is little 

 gain in weight in Group C, which comes in the m.iddle ten days of August, 

 or in Group D, which comes in the first ten dn.75 of September, perhaps 

 because it is already close to the time for turning southv/ard. The 

 proportions of each group taken throughout the Yifhole fishing season are 

 Group A 75'% Group B ICfi',, Group C 3'*^, and Group D 11!^, which agrees with 

 Uda's statement(l^ that on the average SO;-^ of the skipjack from the 

 Northeastern sea area are medium-sized (500-1,000 m-omme ) . 



As for the distribution of the various groups on the fishing grounds, 

 Group A, which has moved north from the waters off Nojimasaki in the last 

 ten days of June, is joined by Group B in the last ten days of July, In 



(1) Uda, Michitaka. Bull. Jap, Soc. Sci. Fish. 7 (2), 1938. 



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