26o DISCOVERY REPORTS 



Work under the first of these headings provides a basis upon which it will ultimately 

 be possible to make a specific comparison between the whales of diff'erent localities 

 (using this word in its broadest sense), and thus to ascertain whether there are, asso- 

 ciated with different localities, any specific or sub-specific differences. From informa- 

 tion of this kind one may be able to judge the possibility of the replenishment of 

 the stock of whales in one locality from another, and to estimate within what limits 

 it is possible for migrations to take place. The North and South Atlantic, for 

 instance, must be regarded as two different localities in which both Blue and Fin 

 whales commonly occur. They are rarely seen in equatorial waters as a general 

 rule, but, as Harmer (1928) has pointed out, both species are caught off the coast of 

 Ecuador, which is so near the equator that it is difficult to say whether they actually 

 belong to the northern or southern hemisphere, or both. At any rate, the possibility 

 of these whales crossing from one hemisphere to the other has to be considered. If it 

 can be shown that there is even a slight racial distinction between the whales of the 

 two hemispheres such a possibility is ruled out. Similarly, the whales found in South 

 African waters must be compared in respect of their specific characters with those of 

 the Dependencies of the Falkland Islands. 



Perhaps the most important part of the work is concerned with the breeding of 

 whales. This includes a study not only of their breeding habits, but also of their growth 

 and life history. Information is needed on the seasons and localities at which pairing 

 and parturition take place, the nature of the oestrous cycle, the frequency of the 

 recurrence of pregnancy, the lengths of the periods of gestation and lactation, the rate 

 of growth and the intervals between the various stages and events in the sexual life. 

 With a knowledge of these processes it is possible to say in what circumstances hunting 

 is liable to do the most damage and to judge the general ability of the stock of whales 

 to withstand or recuperate from the effects of hunting on a large scale. 



The study of breeding and growth is closely related to the problems of migration, 

 distribution and feeding of the whales, many of which are, of course, beyond the scope 

 of the work at whaling stations. It is here, however, that these direct observations on 

 the whales may be made to supplement the work of the ships, which is concerned 

 mainly with the whales' environment. The examination of the food in the stomachs 

 of the whales, for example, is of value for comparison with the catches of plankton at 

 sea, and by systematic measurements of the thickness of the blubber a check can be 

 kept on the variations in the condition of the whales at different seasons. 



Important information is to be had from a study of the different classes of whales 

 which go to make up the populations of different localities. There is evidence of a 

 certain amount of segregation of these classes (i.e. whales of different sexes, ages and 

 stages in the reproductive cycle) and it is necessary to study their local movements 

 and times of arrival and departure in different localities. 



Since the breeding of whales is governed by a seasonal periodicity it is obviously 

 desirable that observations should be made over the whole year, so that the whales 

 can be studied at each stage in the reproductive cycle. The whaling season in the 



