Figure 15 . Distribution of tuna larvae in central 

 Pacific. The values given in the graph are based on the plankton 

 tows taken on HUGH M.SMITH cruises 5, 8^ and II. When tuna 

 larvae are less than 5 millimeters (one -fifth of an inch), we have 

 not been able to identify them as to species. However, we find it 

 possible to identify larvae of yellowfin after they have reached 

 more than 5 millimeters of length. It is likely that many of the 

 larvae designated as "all other tuna larvae" are also yellowfin 

 tuna. 



Figure 16. Index to racial difference of yellowfin 

 between sample localities. In table 5 are listed the numbers of 

 yellowfin tuna whose morphometric nneasurennents entered the 

 calculations on which figure, 17 is based. The numerical values 

 given in this figure are the "reduced coefficient of racial likeness" 

 computed according to the formula: 



R C R L = 50 ^_ • -^ S ^-L r—^ V- -1 



= 50 (hij^) 



in which m is the mean of the sth character estimated for 100 cm. 

 s 



fork length, cr the standard error of estimate of the regression 

 of the sth character on fork length, ns the number of observa- 

 tions of the sth character, n^ the nnean number of observations 

 of all characters in the sample and M the number of characters. 

 The symbols s' and n^ refer to the characters in the second 

 sample . 



Figure 17 . Equatorial commercial fishing. Because 

 of the especial interest attached to the commercial aspects of 

 equatorial fishing results there is given herewith in table 6 the 

 results of each day's fishing by the CAVALIERI. Of the fish 

 included in this table, 17. 7% of the yellowfin. 16. 9% of the bigeye 

 and 10. 3% of the skipjack were damaged by sharks. It is estimated 

 that the damage on approximately half of these was slight enough 

 not to have affected their commercial acceptability. The yellow- 

 fin taken east of 145° W. longitude averaged 148 lbs. each while 

 those taken west of this meridian averaged only 128 lbs. 



43 



