of necessity, the sexes have been grouped in the 

 latter, it is unlikely that size differences between 

 the sexes will affect the conclusions. 



Throughout the year in the central 

 equatorial Pacific the modal length of the group 

 of larger yellowfin is between 145 and 150 cm. 

 (131-145 pounds) (figs. 7, 8). In the western 

 Pacific (140°E. -179°E. )!/, however, the modal 

 length of the group of larger yellowfin was nearly 

 always between 127 and 137 cm. (88-110 pounds) 



4/ 



— These measurennents are taken from 



Murphy and Otsu (1954), pages 16-17. These 



authors have used 5-cm. size groupings. 



(fig. 9). However, the secondary modal group 

 centers near 110 cm. (57 pounds) for both 

 areas throughoutthe year. Thus, at all seasons 

 there is a marked difference in the average 

 size of the group of larger yellowfin present in 

 these two areas and similarity between the 

 secondary modes. 



Interyear Size Variation 



Because of inadequate samples, it is 

 not possible to examine the equatorial yellow- 

 fin thoroughly for variation in modal size be- 

 tween years, though the evidence suggests 

 little year-to-year fluctuation in modal position. 

 For instance, the important modes for the 1951 

 through 1953 samples (fig. 7) from the centrfil 



I M I { M 1 I I I I I I I I I M I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I { I I I I I I I I I I I I I I 



NORTH AMERICAN CRUISE I 

 JANUARY 27- FEBRUARY 28 

 (FEBRUARY 12 MID- DATE) 

 MALES N= 172 



FEMALE N = II7 



NORTH AMERICAN CRUISE 2 

 MARCH IB -APRIL 2B 

 (APRIL 7 MID- DATE) 

 MALES N=384 



JOHN R MANNING CRUISE 20 

 MAY 17- JUNE 15 

 (JUNE 2 MID-DATE) 

 MALES N=I98 



FEMALES N = I43 



I I II I I i I I 

 160 ' 170 



LENGTH IN CENTIMETERS 



Figure 8. --Length-frequency distributions of equatorial yellowfin from 

 155°W.to 165°W. longitude taken during 1954. 



