FUR-SEAL CENSUS, PRIBILOF ISLANDS, 1917. 103 



Number and Distribution of Dead Pups in 1917. 



• Estimated. 6 Based on estimated number of pups. 



THE BREEDING COWS. 



LOSSES AT SEA. 



The fate of the fur-seal herd is directly dependent upon the breeding 

 females. To prove this statement it is only necessary to refer to the 

 fact that only two males are required to 100 females for breeding pur- 

 poses, and it should be the object of the Government to spare no 

 efforts in the protection and conservation of the females. 



The number of breeding females in any one year is known to be 

 equal to the number of young because each cow gives birth annually 

 to one pup. Therefore the cows have increased from 81,984 in 1912 

 to 128,024 in 1917. This is a gain of 46,040 or 56.16 per cent, an aver- 

 age increase for five years of 9.36 per cent. This annua] percentage 

 of increase of the class in which we have most concern appears and is 

 low, but it should be constantly borne in mind that it can not be ex- 

 pected, naturally, to materially increase in the future. During these 

 five years the cows have had almost absolute protection as far as molesta- 

 tion by man is concerned. The great loss occurs at sea from unknown 

 causes. It is known that the whales of the genus Orca devour seals 

 to a greater or less extent, and if this is not the chief enemy there must 

 be another which lives at sea and is at present unknown. The losses 

 at sea in the first three years of their lives have been found to approxi- 

 mate 50 per cent of the seals born. 



