338 



WHALES 



Figure 184. Northern limits of Blue and Fin Whales in 

 the .A". Pacific. {Ormira, 1955.) 



north of the Aleutian and the Komandorskie Islands, Fin Whales 

 penetrate deep into the Bering Sea (Fig. 184). The reasons for this 

 difference in behaviour are not yet plain, but must probably be sought 

 in the distribution of their food. 



It is moreover believed that the Antarctic, in addition to Ijeing larger, 

 is also more plentiful in plankton supplies than the Arctic, and that 

 Antarctic plankton is richer in fats. In the absence of more detailed 

 investigations, scientists base this opinion on the fact that northern whales 

 are generally smaller and thinner than their southern counterparts. 



A. Jonsgard, Prof. Ruud's chief collaborator, who made a special study 

 of this subject, found that the average length of Fin Whales caught in 

 the Antarctic was 68 feet for males and 72 feet for females, the correspond- 

 ing figures in the N. Atlantic being 60 feet and 66 feet, and in the North 

 Pacific 59 feet and 64 feet. Antarctic Fin Whales were found to attain 

 sexual maturity at 63 feet and 66-5 feet respectively and, assuming that 

 their northern counterparts attain it at the same age, the corresponding 

 figures for the N. Atlantic and the N. Pacific are only 58 feet and 61 feet 



