CORRELATION WITH FATNESS 



277 



south through the winter, or arriving on the grounds very early, did not improve in 

 condition before the diatoms got a grip on them. The soHd hne quite clearly shows 

 the general improvement in condition of the whales as the season advanced, the tem- 

 porary falling off in January being in accordance with expectation, as it is then that 

 the incidence of the second wave of immigrants, consisting mainly of immature whales, 

 was chiefly felt. It is true that the actual proportion of immature whales in the catches 

 was highest in February (pp. 263-4), but it is believed that this was due partly to the 



OCT 



NOV 



DEC 



JAN 



FEB MAR&APR 



Fig. 7. Skin Diatom Fatness correlation, 1928-9. The average //L % of Fin whales on which thick or ex- 

 tensive film was recorded each month is shown by the pecked line, while the continuous line represents that 

 of the total Fin whales for which full data are available, t = Blubber thickness; L = Length of whale. 



disappearance of some of the mature whales, and partly to an invasion of immature 

 whales moving (probably in a west to east direction, Kemp and Bennett, 1932, p. 180) 

 within the Antarctic Zone. Not only was the condition of the whales caught in February 

 better than that of those taken in January, but the percentage infection of the February 

 whales was nearly as high (Fig. 3). Indeed it would seem from the diatom data that, 

 during the 1928-9 season, the second wave of migration began as early as December 

 with an unusually large proportion of mature whales, and that many of the later 

 immature arrivals had already spent some time within the Antarctic Zone. 



