Table 1. --Number of ships and fish sampled by month and by area. 



Figures enclosed in parentheses show the number of ships (cont'd) 



1951-'52 (1951 season) 



1952-'53 (1952 season) 



the manner in which these modes appear, it is 

 clear from the figure that this differs marked- 

 ly from area to area. If we follow individual 

 modes through the various sea areas, we can 

 recognize various degrees from clear existence 

 to alnnost no indication of existence. This sort 

 of variation arises from differences among the 

 sea areas in the relative abundance of large 

 and small fish. 



In order to compare differences of this 

 sort, figure 2 has been prepared, showing the 

 yearly length composition by sea areas. 

 According to the figure, the modes miade up of 

 groups of smaller fish predominate in the more 

 westerly areas, while the modes made up of 

 larger fish are more predonninant in the east- 

 erly areas. This sort of relationship is even 

 more clearly recognizable when the data are 

 separated by areas and by years. In other 

 words, the proportion of the smaller size 

 groups is greater in the nnore western sea 



areas, and that of the larger size groups is 

 greater in the more eastern sea areas. 



Cases can also be seen in which there are 

 slight displacennents in the positions of t h e 

 modes as between sea areas. To cite conspic- 

 uous examples of this sort in figure 1, there 

 are the modes at 109-128 cm. in 1950, 89-104 

 cm. and 129-152 cm. in 1951, and 113-136 cm. 

 in 1952. In particular, for the mode at 113-136 



cm. in 1952 there is a pronounced displacement 



o , o 

 as between the area of 150 -165 E. and the area 



east of 180 . If we examine this situation in 

 view of the monthly distribution of the measure- 

 ments as shown in table 1, we see that the 

 measurements for the former were taken mostly 

 in the first half of the measuring period, where- 

 as the measurennents for the latter were taken 

 entirely within the last half of the period. It is 

 presumed that this discrepancy in the time of 

 measurement is part of the reason for the dis- 

 placement of the mode. However, a rather 



24 



