FISHERY BULLETIN: VOL. 87, NO. 1 



within a year. The larger differences that do exist 

 tend to include stratification by area. If a normal 

 distribution is assumed, the only significant dif- 



ferences at a 0.05 probability level among the 

 stratifications within a year (i.e., 1981, 1984, and 

 1986) would be in stratifications which include area. 



Sooon 



4000- 



3000- 



o 



o 



o 



1 2000- 

 



1000 



0* 



o %° 



o °ooo 



^"^^ 



o o 

 o 



° 9, o 



o O o o 



o o °o o ^ 



° ^8s 



O o 



100 200 300 400 500 



Effort — days fished plus searched 



o 



5000-1 



4000- 



3000 



•t 2000 



« 



1000 



100 200 300 400 500 



Effort — days fished plus searched 



Figure 3.— The relationship between monthly yellowfin tuna catch and effort by Japanese purse seiners. 

 The points have been connected in the temporal sequence in which they occur. 



128 



