24 FUR-SEAL FISHERIES OF ALASKA IN 1910. 



be present in 1909, the decrease between the years, 2,009, represents 

 a loss of 4.3 per cent. 



This for all practical purposes, is a fairly accurate measure of the 

 number of breeding cows, which constitute the most important 

 factor in the herd. While merely an estimate, the number is close 

 enough to actual conditions to be approximately correct. A loss of 

 only 4.3 per cent in the breeding cows from the pelagic sealing which 

 has been practiced with such assiduity during 1910 would seem too 

 small. However, the statistics of the seal herd for the last few years 

 demonstrate that the rate of decrease during this period has not 

 been large, and it is not out of the way to believe that it was small 

 in 1910. 



CENSUS OF ENTIRE SEAL HERD. 



Beyond the breeding cows and pups, estimates of which contain 

 much of accuracy, an estimate of the whole herd is very difficult to 

 make, and is unsatisfactory in that it treats of elements which are not 

 susceptible of ascertainment and must be approximated. There are 

 also very few means of testing its accuracy at this or a future time. 

 The methods used are, however, the best that can be devised and tend 

 in the direction of accuracy rather than the opposite. 



ESTIMATE OF HALF BULLS. 



The record of rejections of seals from drives during the summer 

 season of 1910 shows that 1,168 young males too large to be killed 

 were released from the killing fields. It has been established that not 

 by any means all of this class of animals haul in places where they can 

 be enumerated and that the number of those actually turned away 

 should be doubled at least to arrive at the whole number in existence. 



By doubling the number found, 1,168, we would have 2,336 half 

 bulls, from which we may look for recruits to the breeding bulls. 



ESTIMATE OF 2-YEAR-OLDS. 



In 1908 it was computed that 53,884 pups were born. Being 

 equally divided as to sex, one half, or 26,942, were males and an equal 

 number females. 



In 1909, if we allow the diminution of 50 per cent for mortality at 

 sea, which has been taken heretofore to occur among the pups during 

 their first migration, one-half of these would return in 1909 as yearlings. 

 There should have been then in 1909 by this method of computation 

 13,471 yearling males and an equal number of females. These, with 

 a loss of something like 10 per cent, would return in 1910 as 2-year- 

 olds to the number of approximately 12,124 of each sex. 



We should have in 1910, therefore, by this computation, over 

 12,000 virgin or 2-year-old cows and an equal number of males. 



