FUR-SEAL CENSUS, PRIBILOF ISLANDS, 1918. 
By G. Dattas Hanna. 
SCOPE OF 1918 CENSUS. 
The census of the fur-seal herd resorting to the Pribilof Islands 
in 1918 was taken in the usual manner. It is gratifying to note 
that a continued increase is shown. The important element of the 
herd, the breeding cows, began to gain immediately upon the cessa- 
tion of pelagic sealing in 1911. The influence of this has probably 
ceased to exist by this time and the herd appears to have settled 
upon a normal annual rate of increase of about 10 per cent. The 
actual average for seven years has been 9.78 per cent. 
Information procured by Agents Fassett and Proctor in seal killings 
has been freely used in the census computations. Those actually 
assisting in the rookery counts were C. E. Crompton and the late 
A. C. Reynolds. The Bureau was deprived of the important assist- 
ance in field work of Dr. Harold Heath through an unfortunate 
accident in which he was severely injured. A cliff caved away as 
he was passing along Tolstoi Point and in the fall upon the rocks 
below he suffered fractures of both legs and of several face bones. 
The Coast Guard cutter Unalga furnished transportation between 
the islands at the proper times for census work. 
The plan of the 1917 census was followed closely. Harems were 
counted on all rookeries at the height of the breeding season and 
enough pups were counted later to ascertain the average harem. 
With this as a basis, the total number of pups was computed and 
also the remainder of the information so necessary to a thorough 
understanding of the subject was derived. Little could be accom- 
plished in way of area computations. 
Commercial killing in 1918 furnished an opportunity to test the 
estimates of bachelors of previous years. The quota taken was larger 
than in any year since 1889, and it was the general opinion of all con- 
cerned on the islands that the figures for each age which had been 
computed in advance were conservative. Age determination of all 
seals killed, by measurement of the carcass, has made it possible to 
not only keep the reserve required by law, but also to state with a 
reasonable degree of accuracy the number of any one class remaining — 
for killing in subsequent years. The estimates are believed to be 
under rather than over the actual number of each class in existence. 
PUPS. 
Pup counting began just as soon as it was possible to enter the 
rookeries with ‘ekeonable safety to human life and continued until 
the number which was swimming made the figures obtainable subject 
to too great an error to warrant further work. The same field 
methods were used as in former years. As in 1917 those rookeries 
were selected for counting which were known from a records and 
observations on the ground to be representative of the herd. The 
average harem thus ascertained proved to be almost exactly the 
same as that which was found in 1917, and it appears from all avail- 
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