MIGRATIONS AND DISTRIBUTION 237 



whales are found. It gives no indication of course of the distribution of whales in the 

 Pacific sector, since whaling has not been conducted there. Humpbacks can also be said 

 to have a circumpolar distribution, but this distribution is less continuous, for they have 

 a tendency to concentration in some regions and scarcity in others which is more marked 

 than in Blue and Fin whales. There is less information about Sei whales. Table 9 shows 

 that they appear in the catches of South American, African and Australian stations, and 

 the species is no doubt circumpolar, but it is possible that, like the Humpback, it occurs 

 more commonly between some meridians than between others. 



The edge of the pack-ice constitutes the approximate southern limit of distribution of 

 Blue, Fin and Humpback whales, but it is doubtful whether Sei whales ever penetrate 

 into such cold water. 



The distribution of whales naturally cannot be understood without information on 

 their movements and migrations, for whales are constantly on the move and travel over 

 great distances. Some distinction has to be made between migration and local move- 

 ments. The term 'migration' is used here to imply long annual journeys between the 

 Antarctic and temperate or tropical waters, but there is not always a very clear distinc- 

 tion between such journeys and certain regular local movements such as Rayner (1940) 

 has described. 



The evidence for believing that whales undertake regular annual migrations is partly 

 direct and partly indirect. Almost the only direct evidence is furnished by the marking 

 of whales (see Rayner), but before the results of that work became apparent there was 

 plenty of circumstantial evidence of migration. For Humpbacks in particular the evi- 

 dence is very clear ; the routes of their migrations lie within comparatively narrow limits, 

 especially in tropical coastal waters, and can thus be more easily traced than in the other 

 species. For Blue and Fin whales direct evidence is slight, but there are various items 

 of indirect evidence which collectively are very convincing. 



HUMPBACKS 



Since our ideas of the habits of other species are assisted by our better knowledge 

 of the habits (or at least the migrations) of Humpbacks, it will be better to take the 

 latter species first and to consider in full the major features of its distribution and 

 migrations. 



Various writers have shown how the migrations of this species are indicated by the 

 statistics of catches at different times and places. It is to be found in summer in 

 Antarctic waters and in winter in tropical regions, and its movements up and down the 

 African and Australian coasts can be followed by direct observation. A good survey of 

 the subject is given by Matthews (1937) who refers to publications by Risting (1912), 

 Olsen (1914-15), Lillie (1915), Hinton (1925), Harmer (1931), Dakin (1934) and 

 Townsend (1935). It is evident that the main herds of migrating Humpbacks penetrate 

 far into tropical waters. At Natal they are taken early in the winter on their way north 

 and later in the season on their return south. On the west side of South Africa the north- 

 ward-moving Humpbacks approach the coast north of Saldanha Bay and follow it up 



