452 



DISCOVERY REPORTS 



* Maturity doubtful. 



The columns here are headed by the supposed actual ages of the whales (on the 

 assumption that two years elapse between birth and sexual maturity). Thus a whale in, 

 say, its second year after maturity is in its fourth year after birth. 



It will be realized that the exact distribution of the numbers of whales among the 

 groups and sub-groups in the table is simply an expression of the probabilities so far 

 as they can be understood at present, but the analysis at least strongly suggests that in 

 the first two seasons at South Georgia a considerable proportion of the adult female 

 Blue whales killed were not more than four or five years old, whereas in the 1926-7 

 season the majority had lived beyond this age. 



In the case of Fin whales, the grouping shown in the frequency curve is not perhaps 

 very well defined, but Group i may be taken as including whales with from one to 

 seven corpora lutea in the ovaries. Group 2 those with from eight to fifteen, and Group 3 

 the remainder. The analysis is as follows : 



Here the presumed age distribution shows greater similarity in the different seasons 

 than in the case of Blue whales. 



The tables suggest that in both species the majority of adult females killed are from 

 about four to six years old. It must be emphasized that this is a very tentative con- 

 clusion, but it is interesting to note not only that Blue and Fin whales grow to sexual 

 maturity in a remarkably short time, but also that there is some evidence to suggest 

 that the whales killed are on the average unexpectedly young. 



