i6z DISCOVERY REPORTS 



to serve the total of 97,71 1 cows at the rate of 7-28 cows per bull, and if the killing were 

 so great (42,000) as to leave only such a number as should be reserved for the cows of 

 the year, the accession at the beginning of 1938 would raise the total to 23,005, which 

 would be in the ratio of one bull to every 4-33 cows of the 99,665 available in that 

 season. But the extent to which newly adult bulls should take part in breeding is 

 questionable. 



Calculations have been made on the basis of a killing of 15,000 annually from 1937 

 onwards, and they result in a minimum figure of 6649 bulls as the residue after killing 

 (in 1947). These should receive an accession of 16,518, making a total of 23,167 bulls 

 for the breeding season of 1948. The 23,167 bulls would be expected to serve 104,293 

 cows, and 17,208 virgins making a total of 121,501, an average of 5-24 cows per bull. 

 After 1947 the residue increases. 



It is my opinion that with the herd already in a state of equilibrium an annual killing 

 of 10,000 could be contemplated with equanimity, and that if the rate of increase is 

 only 2 per cent a somewhat larger killing should not be injurious. 



It must, however, be emphasized that these are estimates and that the management of 

 a herd of seals is inevitably empirical. Constant attention is required and it should be 

 remembered that changes may be found to be necessary in fundamental figures such as 

 those for length of life, optimum proportion of bulls to cows, or death rates. In the 

 management of the Pribilof Islands fur seal assumed death rates have had to be altered 

 from time to time in order that the estimates should fit the observed facts. 



Since they might well have been written with reference to the herd of sea lions in the 

 Falklands I cannot do better than conclude with the following quotation from the 

 "Report on the Fur Seal of the Pribilof Islands" (Osgood, 1916). 



The nature of sealing as a business is such that restrictions of a fixed and absolute character are 

 highly impractical. Living animals subject to the ravages of disease, to the inroads of natural enemies, 

 to the vicissitudes of an (unusually) stressful existence and to the varying results of peculiar breeding 

 habits cannot be successfully managed under inflexible rules laid down in advance. 



The establishment of close season for game animals is quite a different matter from the restriction 

 of killing of fur seals. 



Among wild animals the fur seal is unique in many respects. Although not actually under 

 domestication it is by nature and habits almost strictly comparable to a domestic animal and the 

 principles governing its management should unquestionably be those employed by breeders of stock. 

 Rigid rules of procedure, therefore, are as inadvisable in the case of seals as they would be with 

 horses, cattle or sheep. So far as possible regulations should be sufficiently elastic to take advantage 

 of conditions as they arise. The number of males which should be killed or reserved cannot, in the 

 nature of the case, be absolute. 



Whether the herd be large or small, diminishing or progressing, good management demands. . . 

 that action may be governed by circumstances. 



Inflexible rules applied to living animals are dangerous under any circumstances. . . . 



The relative proportions of males and females should be the same in a herd of a thousand seals as 

 in one of a hundred thousand or a million, and in any case it is wholly a matter of proportion not of 

 fixed numbers. 



