298 



U.S. BUREAU OF FISHERIES 



AGE CLASSES 



Seals are divided into age groups according to the length of body, it 

 having been found by repeated tests that this is the most satisfactory 

 method of fixing the age of the animals selected for killing. These 

 lengths have been applied to seals ranging from 1 to 6 years of age, 

 and they constitute the gage by which the age of all male seals killed 

 in 1933 Avas determined. This standard of measurement is not in- 

 flexible, however, as seals do not grow at exactly the same rate, but 

 the variation from the accepted length of a seal of a certain age is 

 regarded as inconsequential. The limits of the various age classes 

 are shown in the table following: 



Age classes of male seals, Prlhilof Islands 



Ages of seals killed on Pribilof Islands, calcivdar year 1933 

 [On basis of classification shown in preceding table] 



1 Cows unavoidably and accidentally killed or found dead. 



Some of the seals recorded in the above tabulation as 2-year-olds 

 and 4-year-olds probably were 3-year-olds, as not all male seals of a 

 given age fall within the length limits assigned for the males of that 

 age. As far as possible, the killings in 1933 were confined to 3-year- 

 old males. 



KESERVING OPERATIONS 



No 3 -year-old male seals were marked for the breeding reserve in 

 1933. It was evident at the close of the season that the number of 

 adolescent males of this age class was ample to maintain in subse- 

 quent years the supply of bulls in sufficient strength to meet all 

 breeding requirements of the herd. 



COMPUTATION OF FUR-SEAL HERD 



Following the procedure of other years, Supt. H. J. Christoffers 

 again computed the number of seals in the Pribilof Islands herd at 

 the close of the killing season of 1933. The result of this computation 

 shoAvs that the herd now numbers 1,318,508 seals of all ages. This 

 is an increase of 98,607, or 8.08 percent, over tlie number reported in 

 1932. A more detailed summation of the seal census is given else- 



