DISTRIBUTION AND MIGRATION 335 



schools from the New Zealand sector migrate north mainly along the east 

 coast, and back mainly along the west coasts of the islands. This pheno- 

 menon has not yet been fully explained. 



Blue and Fin Whales, whose distribution is probably much more 

 dependent on the abundance of their food supply, do not occur in such 

 closed communities, and there is, therefore, a much greater interchange 

 of individual whales from the various zones. Nevertheless, it seems clear 

 from Brown's chart that the vast majority of these animals remain faithful 

 to their Antarctic home grounds, and return there year after year. Thus, 

 in 1952, seven marks dated between 1935 and 1938, were recovered from 

 Antarctic Rorquals in almost the same spots in which they had originally 

 been fired. Naturally, the longer the interval between the firing and the 

 recovery of a given mark, the greater the chance of the whale having 

 shifted its habitat, but the greatest shift so far observed in Fin Whales is 

 50° E. or W. In other words, while some animals may occasionally move 

 to an adjacent area, there are no recorded reports of movements across 

 an entire area into one that is not contiguous. Blue Whales seem to be a 

 little more cosmopolitan, for shifts of up to 87° (i.e. passing two area 

 limits) have been observed. Interchanges of Blue and Fin Whales have been 

 reported between Areas I and II, III and IV, and to a lesser extent IV 

 and V, but hardly ever between Areas II and III, where the Greenwich 

 meridian seems to act as an insurmountable barrier! However, there is 

 one recorded incident of a Blue Whale covering 1,900 miles between 

 Areas II and IV in forty-seven days. 



However, the shift from one area to another rarely occurs in the 

 Antarctic itself, for marks recovered in the same year in which they were 

 fired always show that what shifts there are take place over small distances. 

 Thus, whenever a given whale moves to another zone, it does so only after 

 having spent one or more winters in the tropics, where it probably joins 

 a congener or a school from a neighbouring sector. The precise winter 

 quarters and migratory routes of Blue and Fin Whales are, as we have 

 seen, not adequately known, but it is hoped that when all the observations 

 mentioned on p. 330 are fully analysed, we shall understand the subject 

 much better. It seems likely that, by and large, they migrate at least 

 partly to areas rich in food, e.g. the N.W. coast of Africa, the Bay of Bengal 

 and the Gulf of Aden, and that their routes take them not so close to the 

 mainland as those of the Humpback. This applies particularly to Blue 

 Whales; some sub-tropical whaling stations in South Africa and South 

 America still manage to capture Fin Whales. However, their catch consists 

 inainly of young animals. Mature individuals seem to avoid coastal waters 

 altogether, and tropical whaling stations (e.g. Gaboon) rarely catch any 

 Fin Whales at all. Blue Whales, on the other hand, are often observed off 



