ALASKA FISHERY AND FUR-SEAL INDUSTRIES, 1920, 117 
impaired. It was argued that the herd would be benefited by leav- 
ing it unmolested by man for a period of years and allowing natural 
selection to become effective for a time in reducing the number of 
males. 
In a state of nature the polygamous habits of the animals are such 
that the removal of the excess number of males is effected by fight- 
ing. It was believed by some that only the most virile of the males 
would survive the battles which would inevitably result from the 
failure of man to remove the excess. An improvement in the breed- 
ing stock was thus anticipated. Apparently the fact was overlooked 
that when a finish fight between bulls takes place neither the victor 
nor the vanquished is of much value thereafter as a breeder. Both 
are exhausted. 
When the law of 1912 became effective there were 1,358 harem 
bulls in the herd, or 1 to 59.8 cows. Naturally, no immediate increase 
in the number of bulls nor reduction in the average harem could be 
expected, hence we find practically the same condition in 1913 and 
1914. It was necessary to wait until those animals 3 years old and 
over in 1912 became old enough and strong enough to enter the 
rookeries before any result would become noticeable. 
In 1915 we find a slight increase in the number of bulls. The 
average harem was 48.13. But since those animals 3 years old in 
1912 could not have entered the rookeries until they were 8 years 
old, or in 1917, the cause of this increase in bulls must be looked for 
elsewhere than from the closed season. It could not possibly result 
from anything but ample reserves made by the Government agents 
during the commercial operations in the seasons immediately pre- 
ceding 1912. 
The same is true for the season of 1916, when there was a further 
decrease in the average harem. This was undoubtedly the result of 
reserves made during the season of 1911 and previously. 
In 1917 there was an enormous increase in the number of bulls. 
This was the first influx due to the closed season. The average 
harem went down to 26.39, which we now know to be about as small 
as it can go, regardless of the number of males present. The habits 
of the bulls are such that the massed areas would be the scene of 
continual and disastrous fighting if the males were separated by 
much less than the space occupied by the minimum average harem. 
A further large increase in males in 1918 was due to the absence 
of killing in 1913. This increase, however, failed to reduce the size 
of the average harem from the minimum found the previous year. 
There was thus built up an enormous excess of male life, which no 
known means enabled us to estimate with reasonable accuracy. 
There were no data upon which to estimate a natural loss. For- 
tunately for these computations, we have had the ages of animals 
killed determined for several years. This is accomplished on the 
killing fields by measuring the length of the freshly killed animal 
by means of a pair of beam calipers. The measuring of a series of 
branded males of known age permitted the establishment of stand- 
ards showing the prevailing body length for each age, and the 
recording, in the proper categories, of field measurements of seals 
killed completed the classification. 
By consistent efforts the greater portion of the excess of males 
had been removed by 1920, so that the average harem increased to 
