Figure 1. --Distribution of isotherms on the North 

 Pacific ground. 



March is the time when the 

 strength of the Kuroshio is at its lowest 

 ebb, and this condition can be clearly 

 seen by comparing the results of obser- 

 vations due east of Cape Inubo, shown 

 in figure 2, and the data on sectional 

 observations southeast of Cape Nojima, 

 shown in figure 3 for February, with 

 the months preceding and following. 

 This is the season when the southward 



migration of the albacore comes to an end, and this is thought to be an 



extremely important datum. 



100 



2on 



300 



300 



Figure 2. --Vertical temperature 

 section 300 miles due east of 

 Cape Inubo, 1936, 



Table 2 gives a comparison of the catch rates from year to year. 

 March shows approximately the same sort of relationships as obtained in 

 February. However, it appears that we Ccinnot say that the March catch 

 rates for 1951 were on the whole lower than those for 1949. The unusually 

 high catch rates of 1952 and the particularly low ones of 1950 are the same 

 as in February. The movements of the intermediate zone are not clear 

 because of the scattered character of the albacore fishing in the Kuroshio 

 intrusion and because of resulting inadequacy of the data, but judging by 

 the 1950 and 1951 data it appears to have been pushed closer to Japan thaji 

 in February (fig. 1). Particuarly in 1951, the internaediate zone obtrudes 

 into the sea areas just along the east side of Japan, with areas of h i g h 

 catches distributed to the south of it between 27 N. and 31 N. and on its 

 east side at 140°E. to 150°E. 



The range of variability in fishing conditions within unit areas is 

 considerably different fronn that of February. The tendency for fishing 

 conditions along the southern edges of the fishing grounds to be quite stable 

 euid with little variation, but with the variability increasing to the northward 

 begins to disappear in March. In the sea areas east of 150 E. in February 

 quite stable values were already shown and we did not see any trend for 

 variability of the fishing conditions to become conspicuous to the northward, 

 but between 140 E. and 150 E. there were still high values for the coefficient 



98 



