the two epecies do not school together. The same situation seems to prevail in the central 

 Pacific (Murphy and Shomura 1953), 



YELLOWFIN BIGEYE BLACK MARLIN 



1 — I — I — I — I — I — I — I — I — I — i — I — I — I — r 



MAY 1951 

 150° - I69°E 



T-T — rn — n — rn — m — i — i — n — r 



JUNE 1951 

 150° - I64°E 



JULY 1951 

 160°- I69°E 



T — i— 1 — n — r— I — n — i—r 



-T — I — I — I — r 



AUGUST 1951 

 150° - I64°E 



1 — \ — I — [ — \ — rn — I — r 



SEPTEMBER 1951 

 150°- I69°E 



OCTOBER 1951 

 165°- ISgoE 



AUGUST 1951 

 170°- I78°E 



n — I — m — I — I — m — i — r-i — r-rn — r 



OCTOBER 1951 

 170°- I78°E 



1° 2° 3° 4° 5° 6° 7° 



1° 2° 3° 4° 5° 6° 7° 



NORTH LATITUDE 



Figure 7. --Latitudinal variation in the catch rates of yellowfin 



tuna, bigeye tuna, and black marlin by months and years. 



12 



