90 ALASKA FISHERIES AND FUR INDUSTRIES IN 1916. 
CENSUS OF THE FUR-SEAL HERD. 
As in previous years, a census of the fur-seal herd at the Pribilof 
Islands was taken in 1916, A census has been taken annually since 
pelagic sealing was abolished, and the results show clearly the rapid 
recuperation of the herd when relieved from the disastrous effects of 
pelagic sealing. 
The censuses of 1912 and 1913 were taken by George A. Clark. The 
1914 census was taken by Messrs. Osgood, Preble, and Parker in con- 
nection with a special investigation made by them, the results of 
which were published in Bureau of Fisheries Document No. 820. The 
1915 and 1916 censuses were taken under the direction of G. Dallas 
Hanna, assisted by other officers of the Alaska service. Owing to the 
different circumstances under which the censuses were taken, the 
development of additional information in regard to the herd from 
year to year, including a better understanding of the annual per- 
centage of mortality in the younger animals, the figures for those 
components of the herd which can not be actually counted in their 
entirety are not exactly comparable. The classes whose numbers 
may be obtained by actual count are harem bulls and pups of the 
season. The idle bulls may be counted with considerable accuracy. 
The number of breeding cows in any season, which class includes all 
females 3 years of age and upwards, is equal to the number of pups 
born that season. 
In computing the number of young seals of various classes in 
1915 and 1916, by making deductions from the number of pups born 
in preceding years, the natural mortality of young seals at sea was 
placed at 35 per cent for the first year, 20 per cent for the second 
year, and 4 per cent for the third year. This assumption calls for a 
survival to the end of the third year of approximately 50 per cent — 
of the seals born. The loss in the fourth, fifth, and sixth years is 
known to be small, and it is believed that the deductions made for 
the losses in the first three years are sufficiently ample to cover those 
of the fourth, fifth, and sixth years. In 1914 the assumed percentages 
of loss were 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 year. 
In 1916 the class of seals which was designated as young bulls in 
the censuses of 1912, 1913, and 1914 was divided imto 5 and 6 year- 
old classes. The young bulls of the 1915 census were considered as 
5-year-olds, and in the table which follows they have been referred 
to that class. At the time the 1915 census was taken it was believed 
that the 6-year-old bulls were included among the harem and idle 
bulls. Deductions from studies subsequently made indicate that 
when the number of idle bulls is equal to more than 50 per cent of 
the number of harem bulls, as was the case in 1916, the 6-year-old 
males are properly excluded from these classes. 
