9 551859'BTtI5JBilil5JIB'ieii9lB'il«5»BJ'ie\59re'l»l59l«'i 



3oiy LengtK 



Figure 1. --Length frequency by fishing season. 



pronounced displacement can be seen in the 

 same mode as between the area of 140 -150 E. 

 and the area east of 180 , and here there was 

 almost no difference in the period at which the 

 measurements were taken. Looking at i t in 

 this way, it is not possible to ascribe all the 

 displacements of the modes for the different 

 sea areas to differences in the periods at 

 which the measurements were taken. If we 

 consider the four examples of displacement of 

 the modes in different sea areas already cited 

 above, we can see that in general there is a 

 tendency for the mode to be displaced to the 

 right in the areas east of 165 E. and to the left 



in the areas west of that longitude. This 

 phenomenon is probably worthy of note in that 

 it suggests the existence of minute differences 

 in the modes depending on the sea area. 

 However, the displacements of this type are ex- 

 tremely small by comparison with those between 

 the modes indifferent years, as will be set 

 forth next. 



Figure 3 shows the length composition by 

 years, the even-numbered years being repre- 

 sented by solid lines and the odd-numbered years 

 by broken lines. As is clear from the figure, 

 there is a considerable degree of similarity 



25 



