Considering the distribution in relation to latitude, it is evident 

 from figure 2 that during February and March the zone of highest 

 yellowfin abundance straddled the Equator. During the period of May- 

 August the center of abundance lay about 2 degrees north of the Equator 

 (fig. 2). In December there appears to have been a small concentration 

 centered north of the Equator (except for the high catch at a single sta- 

 tion south of the Equator). Thus we see that during most times of the 

 year the center of abundance of yellowfin was at or a little north of the 

 Equator. The Japanese commercial fishing results (fig. 3) tend to con- 

 firm this conclusion in that they show yellowfin to have been more abun- 

 dant between the Equator and 5 N. than they were north of that latitude 

 at all seasons in which any fishing was done in these latitudes. The 

 Japanese catches do not lend themselves to more refined analysis 

 because the data received by POFI were averaged by 5 degrees of 

 latitude and there was no fishing south of the Equator. 



The temporal changes along longitudes 150 W. and 155 W., the 

 best sampled portions of our study area, are shown in figure 4. In this 



area the average yellowfin 

 catch during February was 

 small (2.4 per hundred 

 hooks) at a time when good 

 fishing was found farther 

 to the east. Catches were 

 higher during May (averag- 

 ing 5.5 per hundred hooks), 

 but were smaller than those 

 experienced further west. 

 The highest average yellow- 

 fin catch (7.3 per hundred 

 hooks) of the year was 

 attained during August, 

 and during this same 

 period poorer fishing was 

 found to the west. Finally, 

 rcO during December fishing 



was again poor along 150 

 W. and 155°W. (1.6 per 

 hundred hooks). 



FEB 



MAY 



AUG 



DEC 



1953 



Figure 4. --Temporal variation of yellow- 

 fin abundance for stations between the 

 Equator and 5 N. latitude at 150 ■ 

 longitude (data from appendix tables 6-11). 



Thus there is evidence that there were geographic shifts in the 

 yellowfin population near the Equator with time, but these shifts cannot 

 be precisely described on the basis of the information at hand. In 



