ALASKA FISHERY AND FUR-SEAL INDUSTRIES, 1920. 119 
age of females, but there are so many differences between the sexes 
of this species that the age of the male can no longer be based upon 
that of the female. 
The conditions outlined above are those which are believed to 
exist when there is a great excess of males. If they had been re- 
moved by man so that only approximately enough remained for 
breeding purposes, the losses during the seventh, eighth, and ninth 
years would not be so heavy. Also it is probable that the bulls live 
longer when there is no fighting than when they have to wear them- 
selves out in maintaining a harem position. 
It, therefore, becomes apparent that conditions which obtained 
during 1917, 1918, 1919, are not normal and may never occur again. 
Everything now indicates that the younger animals suffered a 
practically constant mortality until the seventh year, and then their 
losses amounted to 50 per cent or more annually. Under normal 
conditions with the great excess removed by man, the loss after the 
seventh year would be variable and dependent upon the care given 
to the reserving of a proper number of bulls. 
It seems unnecessary here to make arbitrary assumptions for the 
annual losses of the class which was termed in 1917-1919 “surplus 
bulls.” It is definitely known that they were greater than the losses 
assumed and deducted. Thus in 1919, 50 per cent was estimated to 
have been the loss from the third year to and including the surplus 
bull class; that is, animals 7 years old and over. If the loss had 
been estimated at 50 per cent from the third year to the seventh 
and at least that much annually thereafter, 1t would have come nearer 
the actual condition. But there was nothing until 1920 which would 
cause one to suspect that the loss had been so enormous. 
It now remains to determine what the annual loss of males is from 
the third year on, when average conditions accompanying commercial 
work exist. A division which is more or less arbitrary for all ages is 
as follows: First year, 35 per cent; second, 15 per cent; third, 10 
per cent; fourth, 10 per cent; fifth, 10 per cent; sixth, 20 per cent; 
seventh, 20 per cent; eighth, 25 per cent; ninth, 30 per cent; tenth, 
40 per cent; eleventh, 50 per cent; twelfth, 60 per cent; thirteenth, 
70 per cent; fourteenth, 80 per cent; fifteenth, 100 per cent. 
Considerable of the above is conjecture, but it is believed to rep- 
resent fairly accurately the conditions existing in 1920. It will be 
noted that there is a slight revision of the percentages lost from the 
first to the third year. This does not materially affect the result and 
gives a working basis for the future. Doubtless additional investi- 
gation will adjust any irregularities in the table. It has been used 
in the preparation of the final census for 1920. 
These new percentages of loss were obtainable in 1920, because 
early in the season it was seen that the surplus believed to be in ex- 
istence from the accumulation of the closed period did not appear. 
It was evident that if the bulls were coming at all they would have 
been at the islands before the middle of July. Since they did not 
appear at that time it was recommended that no more be removed 
from the herd. As it turned out the counts at the height of the sea- 
son showed that a few more could have been removed with safety. 
