ALASKA FISHERY AND FUK-SEAL INDUSTRIES, 1920. 117 



impaired. It was argued that the herd would be benefited by leav- 

 ing it umnolested by man for a period of years and allowing natural 

 selection to become effective for a time in reducing the number of 

 males. 



In a state of nature the polygamous habits of the animals are such 

 that the removal of the excess number of males is effected by fight- 

 ing. It was believed by some that only the most virile of the males 

 would survive the battles which would inevitably result from the 

 failure of man to remove the excess. An improvement in the breed- 

 ing stock was thus anticipated. Apparently the fact was overlooked 

 that when a finish fight between bulls takes place neither the victor 

 nor the vanquished is of much value thereafter as a breeder. Both 

 are exhausted. 



AVhen the law of 1912 became effective there were 1,358 harem 

 bulls in the herd, or 1 to 59.8 cows. Naturally, no immediate increase 

 in the number of bulls nor reduction in the average harem could be 

 expected, hence we find practically the same condition in 1913 and 

 1914. It was necessary to wait until those animals 3 years old and 

 over in 1912 became old enougli and strong enough to enter the 

 rookeries before any result would become noticeable. 



In 1915 we find a slight increase in the number of bulls. The 

 average harem was 48.13. But since those animals 3 years old in 

 1912 could not have entered the rookeries until they were 8 years 

 old, or in 1917, the cause of this increase in bulls must be looked for 

 elsewhere than from the closed season. It could not possibly result 

 from anything but ample reserves made by the Government agents 

 during the commercial operations in the seasons immediately pre- 

 ceding 1912. 



The same is true for the season of 1916, when there was a further 

 decrease in the average harem. This was undoul)tedly the result of 

 reserves made during the season of 1911 and previously. 



In 1917 there was an enormous increase in the number of bulls. 

 Tliis was the first influx due to the closed season. The average 

 harem went down to 2G.39, which we now know to be about as small 

 as it can go, regardless of the number of males present. The habits 

 of the bulls are such that the massed areas would be the scene of 

 continual and disastrous fighting if the males were separated by 

 nmch less than the space occupied by the minimum average harem. 



A further large increase in males in 1918 was due to the absence 

 of killing in 1913. This increase, however, failed to reduce the size 

 of the average harem from the minimum found the previous year. 

 There was thus built up an enormous excess of male life, which no 

 known means enabled us to estimate with reasonable accuracy. 

 There were no data upon which to estimate a natural loss. For- 

 tunately for these computations, we have had the ages of animals 

 killed determined for several years. This is accomplished on the 

 killing fields by measuring the length of the freshly killed animal 

 by means of a pair of beam calipers. The measuring of a series of 

 branded males of known age permitted the establishment of stand- 

 ards showing the prevailing body length for each age, and the 

 recording, in the proper categories, of field measurements of seals 

 killed completed the classification. 



By consistent efforts the greater portion of the excess of males 

 had been removed by 1920, so that the average harem increased to 



