ALASKA FISHERY AND FUR-SEAL INDUSTRIES, 193 3 307 



to take care of late arrivals, there is not being maintained an ade- 

 quate reserve for breeding requirements. 



In 1933 it seemed safe to kill 52,747 3-year-old male seals. It was 

 apparent that tiiore were sufficient males over 3 years old to take 

 care of breeding recjuirements, making it unnecessary to reserve any 

 rJ-year-old animals while killing operations were in progress. Ob- 

 servations after the close of the killing season indicated that sufficient 

 3-year-olds remained to assure an ample breeding stock when they 

 enter the surplus, idle, and harem bull classes. The arrival of the 

 annual supply vessel and the consequent work of unloading cargo 

 l)revented the marking of any of these animals. 



For several years prior to 1932 there was each season an unusually 

 large increase over the previous year in the number of killable seals 

 arriving at the islands, but this could not be expected to continue. 

 These large increases, it is thought, were in the nature of a read- 

 justment as a result of leaving a large reserve in 1923 and subse- 

 quent years to compensate for previous close killings. Normally, the 

 average increase in killings Avould not be more than 7 or 8 percent. 

 Any additional increase in the number of seals killed must be due 

 to particularly favorable conditions at sea during the first 3 years 

 of their life. As the Bureau cannot determine what natural condi- 

 tions exist in an}^ year, it is impossible to predict accurately what 

 the take of sealskins will be. 



If an average rate of growth of the herd is maintained, an unusu- 

 ally large increase in the number of seals taken in certain years 

 would necessarily be follow^ed in succeeding years by no increase at 

 all, or even by a decrease. Undoubtedly it often happens that there 

 may be several years with extremely good conditions at sea, followed 

 by several years with poor conditions in respect to food or freedom 

 from natural enemies, which would affect the mortality of the seals. 

 Upon the basis of past experience it would seem that notwithstanding 

 these fluctuations the number of killable seals arriving at the Pribilof 

 Islands will gradually increase to a point where at least 100,000 may 

 be killed annually. The actual size to which the herd msiy increase 

 before natural conditions prevent overpopulation of the sea with seal 

 life is, of course, not known. 



It is interesting to note that starting with the number of 3-year- 

 olds killed in 1918, the firet 3'ear of commercial killing after the 

 5-year closed period, and applying a yearly increase of 8 percent, the 

 number of 3-year-old seals to be killed in 1933 would have been 

 53,946. Actually, there were 52,747 3-year-old seals killed in that 

 3'ear. 



BULLS 



As in previous years, a census was taken of the harem and idle 

 bulls. Portions of some of the larger rookeries again had to be 

 estimated. The Sivutch rookery could not be counted, and it did 

 not seem desirable to show any increase over the number estimated 

 for that rookery in 1932. 



The percentage increase of harem and idle bulls over 1932 was 

 not as large as in other recent years. This would indicate that the 

 larger breeding reserve created during and after 1923 has lowered 

 the average liarem to about the desired number. 



