120 THE FUR SEALS OF THE PRIBILOF ISLANDS. 
REMOVAL OF SUPERFLUOUS MALE LIFE BENEFICIAL. 
Moreover, the removal of this superfluous male life is not only possible, but is 
really beneficial to the herd. As already indicated, the only deaths among adult 
bulls and cows discovered upon the rookeries of the islands resulted from the strug- 
gles of the bulls among themselves or to obtain possession of the cows. In the death 
of young pups also this fighting and struggling of the bulls is a small but by no means 
insignificant cause of loss. In 1896 the great early mortality among nursing pups was 
wrongly ascribed to the trampling of the fighting bulls. But while the more complete 
and satisfactory investigation of 1897 shows another and more important cause, there 
still remains a considerable loss from this source. This loss is now insignificant 
compared with what it was in the wild state of the herd. When the number of adult 
males and females was practically equal, the destruction both among the cows and 
among the pups must have been enormous. It undoubtedly rivaled the ravages of 
the worm Uncinaria in its destructive work and combined with it to offset the natural 
increase of the herd. 
POSSIBILITY OF OVERKILLING. 
While as a general principle the removal of these superfluous males is beneficial 
to the herd, excessive removal would undoubtedly lead to disastrous results. The 
percentage of males required for the needs of propagation is small, but it is essential, 
and if reduced too low or cut off entirely the effect must be injurious. Such excessive 
killing would be felt in the scarcity of bulls, from which cause, through inadequate 
service, the usual increase of pups would not be born and the herd must ultimately 
begin to fail. Itis on this ground that land killing becomes a possible source of 
danger to the herd. 
A HYPOTHETICAL CASE. 
To understand how such killing would act, let us take a hypothetical case. If in 
any given year absolutely every 3-year-old male was killed to fill the quota, this 
would involve the absence of representatives of this class of seals from the reserve of 
bulls for the replenishment of the rookeries in subsequent years. It would not affect 
the breeding bulls, nor the reserves of four, five, and six years. These latter would 
supply the deficiency in the breeding stock caused by old age for at least ten years, and 
it would take that period at least to show the effect of the close killing. If it was 
not repeated, no influence would be felt. The 7-year-old bull of the following year: 
would simply enter the rookeries as a 6-year-old. 
But suppose the killing was continued through a series of years, every 3-year- 
old being killed, the reserve would in time be cut off and the stock of breeding bulls 
would die out. It is impossible to say how long it would take to produce this effect, 
because we do not know the length of the life of the bull. We may infer, however, 
that it is not less than fifteen years, and therefore the injurious effects of this exces- 
sive killing begun in any given year and continued indefinitely would not be seen 
within ten years at least. 
This is only a hypothetical case, but it shows what is meant by too close killing 
of mnales in filling the quota. The killing of males, which would produce immediate 
and disastrous results, must strike at the adult males. To destroy this class or any 
considerable number of them would at once weaken the herd. But there would be 
no object in such killing, and it has never been thought of. 
