and, at the same time, the variability within the area is somewhat greater 

 than it is south of 30°N. Between 31 N. and 32 N. the existence of the 

 intermediate zone can be detected at 150 E. to l60 E. , and we see scattered 

 here and there areas of low catch rates. With the exception of these areas 

 the catch rates are even higher than they are in the more southerly parts 

 of the ground, but their variability is greater. North of 32 N. the inter- 

 mediate zone exercises some effect between 145 E. and 150 E. and, in 

 general, the variability of the fishing grounds is even greater, with occa- 

 sional indications of highly outstanding catch rates. As for the changes 

 from year to year in the position at which the intermediate zone appears 

 (see table 1), in 1949 its position was quite far from the coast, but in 

 1950, 1951, and 1952 its western edge was running southwest to north- 

 east in the vicinity of 35 N. , 145 E. 



The isotherms shown on the supplementary charts are based on 

 data supplied by commercial fishing vessels and are an attempt to show 

 the general picture of the distribution of water temperatures in this fish- 

 ing ground. (The data are for the period of December 10-15 of each of 

 the years covered.) Compajring the pattern in the different years, we see 

 quite well-marked differences in the area where the Kuroshio turns east- 

 ward. In 1949 a zone of high water temperatures is seen intruding in a 

 northeasterly direction considerably farther offshore than in an average 

 year and, as a result, the tongue -shaped zone of low weather temperatures 

 on its eastern side protruding to the southwest was pushed conspicuously 

 eastward ajid was located east of 150 E. longitude. In 1950 and 1952 (data 

 for 1951 are lacking), in comparison with 1949, the area in which the cur- 

 rent swings to the east was located much closer to Japan. The tongue- 

 shaped low temperature water mass on the east side of the main current 

 of the Kuroshio was located right on the intermediate -zone fishing ground, 

 and this change was in good agreement with the annual chajige in the inter- 

 mediate zone. In waters east of 150 E. longitude, as a general rule, the 

 isotherms follow the parallels of latitude and run east and west, but, 

 between the point of eastward deflection of the current and the counter - 

 current, large and snnall vortices are formed which in some years appear 

 to develop on an extremely large scale, forming a good fishing ground. 



Table 2 presents the results of sectional observations made off 

 Kinkazan in 1936 (a year of particularly low water temperatures). 



58 



