230 THE ASIATIC FUR-SEAL ISLANDS. 



CAUSES OP THE DECREASE. 



Three different causes, either of them alone, or in combination with the others, 

 have been generally regarded' as responsible for the undeniable decline of seal life on 

 the seal islands of the Bering Sea and Korth Pacific Ocean, viz, excessive driving of 

 the male seals, raids on the rookeries, and pelagic sealing. It may be well to inquire 

 how each of these alleged causes applies to the conditions prevailing on the Eussian 

 islands. 



It has been claimed that the driving of the male seals results in sapping their 

 vitality and impairing their procreative powers, thus causing a double decline by 

 shortening the life of the individual and causing a smaller number of pups to be born. 

 I have elsewhere in this report discussed this question. Here it will suffice to simply 

 inquire. How do the facts observed on the Commander Islands agree with this theory? 

 I have already summarized the facts, but they will bear a brief repetition. On Bering 

 Island the driving is so easy that even the black pups driven in flocks with the 

 adults are uninjured; yet there was quite a deficiency in bulls, virile and otherwise. 

 On Copper Island the drives are beyond comparison the hardest known anywhere; 

 yet there was a surplus of exceedingly virile bulls; and still, if we may be allowed a 

 comparison with the Pribilof Islands, we may add that the decrease in killablcs on 

 Copper Island is of a much later date than the corresponding decrease on the Pribilofs. 

 Now, if the driving had had the slightest influence upon the numbers of the seals, 

 how did it happen that the seals were increasing while it is a fact that the drives 

 have never been easier, but if anything rather harsher? Nothing seems more clear 

 and logical than this proposition, viz, that if the driving is the cause of the decline, 

 we should expect the falling off in bulls to have taken place on Copper Island, and 

 not on Bering Island; but the reverse is just the case. I am, therefore, compelled 

 to absolve the driving of the responsibilty for the decrease on the Commander Islands. 



The contention that the occasional raids practiced on the rookeries by marauding 

 schooners are materially to blame for the decrease has found but slight support, and 

 the experience on the Commander Islands does not substantiate it. I have shown 

 that the Commander Islands seals were increasing in spite of the numerous raids in the 

 early eighties; I have also shown how the little rockof Eobben Island has continued 

 to yield killable seals in spite of an unparalleled history of raids. It is safe to say that 

 the annual catch of the raiders of the latter island greatly exceeded that of the legiti- 

 mate killing on shore, ^ and yet the falling off" in the yield is not greater than that of 

 the other islands. 



There remains the pelagic sealing. Up to 1892 their was no startling decrease of 

 the female seals on the Commander Islands rookeries, while there had been for a couple 

 of years some difficulty in getting the former number of killables. In 1892 the sudden 

 invasion of the whole body of the pelagic sealing fleet upon the unprotected feeding 

 grounds of the Copper Island female seals took place, followed by similar inroads in 



1 For the theory of overkilling of uiales, as now advocated chiefly liy Mr. Barrett-Hamilton, see 

 ante, pp. 180-182. 



'•' The catches of the schooners which are known to have raided Rohhen Island from 1878 to 1895, 

 together with other illegitimate losses, amount to about 53,000 skins. The total number of skins 

 taken hy the lessees during the same period is a little over 33,000. The proportion is therefore as 

 5 to 3. 



