FUR SEALS AND OTHER LIFE, PRIBILOF ISLANDS, 1914. 33 



from place to place, going far out to feed, passing from one hauling ground to another, 

 and crossing between St. Paul and St. George Islands. Moreover, it is highly probable 

 that a considerable proportion of the yearlings do not come to land at all. Therefore 

 no complete enumeration of nonbreeding seals is possible. 



Since it is from this class of seals that the output of salable skins is derived, a 

 knowledge of their numbers is of the highest importance and it is a lack of such knowledge 

 that has caused much loss to the Government in the past. The fortunate condition 

 which under proper authorization will make it possible to obtain a large part of this 

 knowledge in the future has been discussed in another place (p. 103). For the census of 

 1 91 4, however, only estimates are possible, and they can not be regarded as more than 

 carefully considered approximations. It is with some reluctance that they are put forth, 

 although all conclusions drawn from them are supported by convictions derived from 

 actual observation. Every effort has been made to make them conservative and in no 

 case are they less so than those of previous investigators. 



The basis of the estimates in most cases has been the birth rate. Fixed percentages 

 for assumed natural mortality in successive years plus the number of seals killed have 

 been subtracted from the number born, the remainder being the supposed number sur- 

 viving. The assumed percentages of natural loss are 50 per cent for the first year, 15 

 per cent for the second, 10 per cent for the third, and 5 per cent for the fourth. 

 So far as the percentages have a definite numerical basis, it is that of the quotas which the 

 lessees found it possible to secure during commercial killing. They are the percentages 

 which seemed to prevail during pelagic sealing and therefore are ultraconservative when 

 applied to present conditions. 



Producing but one young annually and subjected to constant killing for more than 

 100 years, the fur seal still maintains itself in numbers which, although reduced, are by 

 no means small. It has made ready recuperative response to every partial suspension 

 of killing and its present condition as shown by observations in the past season is unmis- 

 takably one of rapid increase. Therefore, it is evident that these percentages give results 

 much more likely to be underestimates than otherwise. An underestimate tends to the 

 conservation of the herd by fostering limited killing. All that can be said against it is 

 that it may involve some money loss to the Government. An overestimate, on the 

 other hand, would endanger the herd, and while it might lead to action productive of 

 immediate revenue, it would in the end also cause money loss. 



Yearlings. — These are estimated as one-half the pups known to have been bom 

 in 1 91 3, as determined by the full count made by special investigator G. A. Clark. The 

 theory that 50 per cent of each year's pups are lost during the first season is not as yet 

 definitely proved but may be accepted as closely approximating the truth and as fur- 

 nishing a basis for fair comparison with former estimates. Whatever may be the truth, 

 it is beUeved that the first year's mortality is less than 50 per cent rather than more, 

 so the estimate may be regarded as a moderate one. This loss, of course, includes the 

 pups that die on the islands as well as those lost at sea. The deaths before the migra- 

 tion amount, under present conditions, to from 2 to 3 per cent of the pups bom. 



The total of pups counted in 1913 was 92,269; therefore the yearlings alive in 1914 

 are estimated as 46,135. 



Two-year-olds. — These were bom in 191 2 and were included in the full count of 

 that year which totaled 81,984. On the basis of 50 per cent first year's mortality there 



