32 
FUR-SEAL FISHERIES OF ALASKA, 1909. 
Of course, not a few individuals of the reservations of 1904 and 
1905 were killed by pelagic sealers. Those of 1904 now living had 
to elude the efforts to capture them in the sea made during a period 
of six years. The cumulative effect of six years’ sea hunting upon 
a given class of animals, such as these young males released in 1904, 
must be severe enough to deplete the original number materially. 
No one will claim that of the original 1,000 3-year-olds released in 
1904 all came through to adult estate with a loss attributable only 
to natural mortality. Quite a large percentage died from pelagic 
sealing, but enough escaped the vicissitudes of seal life not only to 
fill all the places made vacant by the deaths of old bulls, but to 
reenforce that class to the point of actual expansion. 
Notwithstanding the assured success of this experiment of reserving 
young males, it may be claimed that the result should have been more 
pronounced, or, in other words, that more bulls should have appeared 
than actually did. Theoretically more should have appeared, but 
our theories are based upon the knowledge of only a few facts con- 
nected with seal life after the seals leave the land. What the actual 
mortality is among these animals from their natural enemies and 
pelagic sealing can not be ascertained, but undoubtedly it is large. 
From the experiment we have learned simply that a reservation of 
2,000 bachelors will not deliver the entire number on the rookeries 
as bulls five years hence, and that, if we want more bulls than actually 
appeared, we must have a larger reservation. 
SIZE OF RESERVATION TO EFFECT INCREASE IN BULLS. 
In 1904 there were approximately 2,300 adult bulls on the rook- 
eries, and in that year the first reservation of 1,000 3-year-olds was 
made. No account is taken of the 1,000 2-year-olds made at the 
same time, for the reason already given that these latter are always 
liable to be killed the succeeding year on land and were reserved for 
the purpose merely of insuring a supply of 3-year-olds for the next 
year’s reservation. 
These 1,000 3-year-olds represented nearly 50 per cent of the 
number of active breeding bulls present in 1904. Wdien the years 
necessary for their full growth had passed it is found that the incre- 
ment of the survivors of this 50 per cent reservation was sufficient 
only to form a slight excess over the number of bulls present the 
preceding year. In other words, it is found that a reservation equal 
to 50 per cent of the adult bulls present was hardly more than enough 
to meet the drains from the usual mortality among rookery bulls. 
From these facts, hardly sufficient though they be, we might 
deduce the tentative principle to be observed in future, should 
further effort be made by reservation of 3-year-olds to meet and check 
