SEASONAL CHANGES IN THE COMPOSITION OF THE STOCK 



273 



The numbers of Blue whales examined in 1939-41 are hardly sufficient for any definite 

 conclusions, and Fin whales fluctuate irregularly. 



At South Georgia there is some indication of a diminishing proportion of male Blue 

 whales, and this again may be due to the late arrival of non-breeding females. In Fin 

 whales the high proportion of males in January has a definite significance, for the same 

 phenomenon has been a feature of several separate seasons. In 1925-6 for instance Fin 

 whales were at first very scarce around South Georgia. About the end of December 

 there was a sudden incursion of this species ; during January they were caught in ex- 

 ceptionally large numbers, the great majority at first being males. In six days the Fin 

 whales examined by the Discovery Committee's staff included forty males and only 

 thirteen females, and the number of males examined in January was twice the number 

 of females. This was clearly an instance of at least partial segregation of the sexes. In 

 1928-9 and 1929-30 again there was a large influx of Fin whales about the New Year, 

 and again in January the number of males examined was nearly twice the number of 

 females. It seems likely that the vanguard of the main herds of Fin whales which 



