EFFECTS OF WHALING ON BALEEN WHALES 



143 



relation between the catches of fin and blue whales per C.D.W. is also 

 different for pre- and post-war seasons (Fig. 2). 



The whaling grounds for blue and fin whales differ, to some extent as 

 regards longitude, but more generally so in respect of latitude. The blue 

 whale is usually found nearer to the pack-ice, to the south of the whaling 

 grounds. For periods when the catch of blue whales is more valuable (that 

 is, as long as blue whales constitute more than one-third of the combined 

 catch of blue and fm whales) it is to be expected that the whaling fleet will 



Stable B.W.U./C.D.W. 



1-2 13 1-4 Iff l'( 



o Pre-war IW2-39 



• Post-war I945--59 



V y'Species of equal value in 

 \ \A^\ \ \catch (raliolB:2F) 



°\ Blue more valuable 



I — I — r- 



0-5 1-0 



Blue/ C.D.W. 



Fig. 2. — Relation between the catches of blue whales and fin whales per C.D.W. 



choose to operate in waters where blue whales are most abundant. Con 

 versely, when blue whales become less important the fleet will largely 

 orientate itself for the catching of /m whales, though blue whales will 

 continue to be caught as well. 



^ In Fig. 2 I have also drawn in oblique lines showing constant values of 

 B.W.U. per C.D.W. for differing values of fm whales and blue whales per 

 C.D.W. It can be seen that the number of B.W.U. per C.D.W. declined in 

 pre-war seasons from about 1-4 to i-o and has shown a sHght increase in 

 post-war seasons. (The values of B.W.U. per C.D.W. are only sHghtly 

 higher if humpback and sei whales are also included.) 



