464 DISCOVERY REPORTS 



3. It has been shown that the ratio of immature whales among the catches is very 

 high, and this is a point of great importance. There are two reasons why the kiUing of 

 immature whales is economically unsound, and more than one previous author has 

 drawn attention to them. In the first place, since an immature whale has had no chance 

 of reproducing itself, its death constitutes, so to speak, a permanent reduction of the 

 stock. In a community of animals, members of which are killed for commercial pur- 

 poses, it is above all essential that the breeding should be subjected to a minimum of 

 interference, and the killing of immature individuals is perhaps the worst form of 

 interference with the natural replenishment of the stock. In the second place the number 

 of immature whales required to produce a given quantity of oil and other products, 

 would enormously exceed the required number of adult whales. 



At South African stations such as Saldanha Bay, where more than 80 per cent of the 

 Blue and Fin whales caught are immature, the hunting is for these reasons far more 

 damaging to the stock in proportion to the value of the products obtained than in South 

 Georgia and the South Shetlands. Even at South Georgia the ratio of immature whales 

 in the catches is undoubtedly high, amounting as it did among Blue whales of both sexes 

 to 42 per cent of the whales examined in the course of the work. Among the Fin whales 

 it came to the more moderate quantity of 23 per cent in the case of males and 28 per 

 cent in the case of females. 



4. The conclusions regarding the breeding season confirm and slightly adjust those 

 reached by previous authors. Perhaps the most important point is that the whales 

 actually engaged in pairing and parturition are not much molested by the whalers. 

 The examination of whales at whaling stations does not throw much light on the where- 

 abouts of the actively breeding whales. The catches at Saldanha Bay indicate that some 

 pairing and parturition takes place off the S.W. African coast, but although there is 

 here an immense stretch of coastal water, so few of these whales are caught that one 

 can hardly suppose it to be the normal destination of the whales which migrate north- 

 wards from any large community of whales in the Antarctic. It seems more probable 

 that the breeding processes normally take place further from land, or at any rate outside 

 the ordinary range of the land stations. It may be that the whales are more scattered 

 at this time, but if they are at all concentrated during the periods of pairing or parturition 

 serious damage would be done to the stock if they were to be hunted at such a time. 

 Without any definite evidence one would expect a certain tendency towards concen- 

 tration at least during the pairing season. 



The protracted period of breeding is a feature which favours the maintenance of the 

 stock, for it implies a certain elasticity of habit and an ability to take the opportunity 

 of pairing when it arises. 



5 . The frequency of the recurrence of pregnancy is of great importance in connection 

 with the maintenance of the stock. An element of uncertainty remains here, but it is 

 certain that except perhaps on very rare occasions an interval of not less than two years 

 elapses between successive pregnancies and it is highly probable that the interval 



