In all years the location of the intermediate zone was somewhat 

 more to the west thsui in January. As a result, the zone of high catch 

 rates on the west side of the intermediate zone is pressed in closer to 

 Japan than it was in January. The pattern of variation from year to year 

 in the location of the intermediate zone appears to continue onfrom Jan- 

 uary, but the zone of high catch rates on the west shows some points of 

 difference in 1951. In this year, because of the extreme approach of the 

 intermediate zone to the coast of Japan, the zone of high catch rates did 

 not develop north of 30 N. but shifted to the sea areas south of 30 N. 

 For the sea area east of 150 E. we do not have adequate data so that 

 annual changes there are not clear. 



The pattern of variation of fishing conditions in unit sea areas 

 between 140°E. cind 150 E. is shown in table 4 and closely resembles 

 the situation in January. In continuation of the situation in the preceding 

 month, the fishing grounds along the southern edge show small variability 

 in fishing conditions, while there is a tendency for the variability to increase 

 toward the northern edge. 



Table 4. --Frequency of coefficients of variation (C. V. ) of catch rates 



o o 



in unit areas, divided by 2 degrees of latitude, between 140 and 150 E, 



Note 



: Averages are 42. 7% for 28°-30°N. , 66. 7% for 30°-32°N. , and 

 93. 1% for 32°-34°N. 



The variability of catch rates in unit sea areas for the waters east 

 of 150 E. is as shown in table 5; the variability is very slight auid hardly 

 einy difference between the northern and southern parts of the area can be 

 detected. In this area the north-south compression of the fishing grounds 

 is extreme and the albacore are accumulated within a narrow range, which 

 is thought to give rise to the stabilized fishing conditions. 



The average weight of the fish landed from this sea area is shown 

 in table 6. As in the preceding nnonth, the fish are bigger along the south- 

 ern edge of the ground and are smaller the farther north one goes. The 

 size also decreases toward the Japanese coast and increases offshore to 

 the east. As compared with January, however, with one exception, the 

 size of the fish is a good deal smaller. 



86 



