SPAWNING OF YKLLOWFIN TUNA 



55 



o 



s 



o 

 a. 



POSITION OF PRECEDING MOOE IN MILLIMETERS 

 Pigube 5. — Scatter diagram showing relation between modal groups of ova in the ovaries, stages E through J. 



tered in the lumina. Of these eight samples, one 

 was collected in June, one in August, five in Octo- 

 ber, and one in November. Thus, the presence of 

 ova remnants in ovaries which show every indi- 

 cation of future spawning gives further evidence 

 in favor of the hypothesis that more than one 

 group of ova is matured and spawned by an indi- 

 vidual fish in a single breeding season. 



It is suggested in figure 3, by the trough at 

 about 0.2 mm. in stages E to J, that many ova 



graduate from the immature to the intermediate 

 group in stages A to D and few in stages E to J. 

 In table 2 we find that fish with ovaries in stages 

 A to D occur from November to May, tapering 

 down to very few by June. This distribution of 

 stages A through D suggests that the intermedi- 

 ate group should be found in largest number by 

 early summer. Thereafter, if the intermediate 

 group furnishes successive groups of ripe ova, the 

 number of ova in the immature group should de- 



