COMPUTATION OF FUR SEALS, PRIBILOF ISLANDS, 1936 
By Harry J. CHRISTOFFERS 
The total number of killable male seals that appeared at the Pribi- 
lof Islands during the season of 1936 was a keen disappointment to all 
concerned. There were several possible reasons for the shortage. 
Probably the most important was the weather that prevailed at the 
Pribilof Islands and throughout the coastal waters of Alaska. During 
the entire season it was abnormally warm, with continual heavy rains, 
neither of which is favorable for the hauling out of seals. Often when 
weather at the islands is unfavorable the seals will go into the water 
and remain there until conditions improve, thereby causing a short- 
age in the kill. It was not merely local weather conditions, however, 
that prevented the seals from hauling out, as the animals were not 
at or in the vicinity of the islands. 
Reports were received of large numbers of seals seen between the 
Pribilofs and Bristol Bay, in the Gulf of Alaska, and in the waters 
below the Aleutian Islands at a time when the bachelors should have 
been arriving at the Pribilofs in large numbers. Most of these seals 
undoubtedly were bachelors, and although it is impossible to say in 
which age class they belonged, a fair percentage must have been 3-year- 
olds. With this in mind, it was felt that commercial killings could 
safely be continued until the last of July and still leave sufficient 
animals of the killable class for breeding requirements. 
There is no particular reason why young males should return to the 
Pribilofs. They are not capable of breeding, and it is the sexual in- 
stinct which principally accounts for their continuing to return to the 
islands. Itis therefore possible that when weather conditions are very 
favorable in more distant waters they will not return. There may be 
also some natural instinct which prevents them from coming to the 
islands when the climatic conditions are not particularly to their liking. 
The above-mentioned reasons for killable seals not returning to the 
Pribilofs this season give the optimistic viewpoint. If none of the 
reasons given caused this year’s shortage of 3-year-old males, then the 
death rate at sea for young animals has increased with the increase in 
size of the herd. It is possible that natural enemies or disease may 
increase at a more rapid rate than the herd increases, or it may be that 
natural enemies were more abundant than usual during the life cycle 
of this year’s generation of 3-year-old males. The more congested 
the rookeries become, the greater the death rate among the pups on 
the rookeries; but this fractional increase in the death rate should not 
cause any extreme shortage of seals. 
In order to provide for a maximum increase in the size of the herd 
it is essential to provide sufficient breeding males. To do this it is 
necessary to kill only from a particular age class. It does not make 
any difference which age class is reserved, but it 1s essential to reserve 
all that are older than the age class selected. 
When the Government assumed direct control over killings, the 
3-year-old class was selected as the most desirable to kill, principally 
because there would be more killable animals on account of the death 
rate between the 3-year-old and 4-year-old classes. It is understood 
that during the leasing period the lessees preferred the skins from 
4-year-old males, as they brought better prices than the skins from 
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