144 U. S. BUREAU OF FISHERIES 



The only apparent loss from killing 4-year-olds rather than 3-year- 

 olds would be that due to mortality during an additional year at sea. 

 On the other hand, the 4-year-olds have larger, heavier furred skins, 

 and they were killed by the commercial companies in preference to 

 3 -year-olds. 



Apparently the only logical way to change over to the killing of 

 4-year-olds would be to discontinue sealing entirely for a season, or 

 to kill about 25,000 3-year-olds during one year and the next year 

 kill only the proper proportion of 4-year-olds and leave all 3-year-olds 

 for the following year. 



It appears certain that it would not be desirable intentionally to 

 kill from two age classes during the same year, although it would 

 thus be possible to discontinue sealing very early by killing half 

 3-year-olds and half 4-year-olds. Tliis would not work out satisfac- 

 torily, for there would be the danger that in order to secure the ex- 

 pected increase in killings each year too many animals would be 

 killed. In a short time there might be a shortage of breeding animals. 

 During the past several seasons when there has been no appreciable 

 increase of killable animals, too many would undoubtedly have been 

 killed if killings had been from both the 3-year-old and 4-year-old 

 classes and if they had been continued until the expected increase 

 were secured. If such a course had been followed, there would now 

 be a grave shortage of bulls, but as killings were from one class only, 

 the condition in this respect is now very satisfactory. 



It appears, also, that about the only way to secure a large percentage 

 increase of killable seals, such as occurred in 1929, is to leave a larger 

 proportion of killable seals for breeding purposes. This was clearly 

 demonstrated in the results obtained from leaving increased reserves 

 in 1923 and 1924. From 1923 to 1929 larger proportions of 3-year-olds 

 were reserved for breeding. Probably, also, there were particularly 

 favorable conditions at sea during this period. The returns from 

 leaving these extra breeders were very favorable. "We have had no 

 increase for the past several years, however, although we have Idlled 

 to the end of July and have made no special reserves of breeders. 



This season it was the intention to discontinue seaUng around July 

 25, but inasmuch as Idllings increased at that time and as harems had 

 not broken up to any great extent it seemed desirable to continue 

 killing a few days longer. 



The records show that proportionately more 2-year-olds and 4-year- 

 olds were Idlled in 1937 than in any previous year. A great deal of 

 this increase over the previous 2 years was due to changes which 

 resulted in more accurate measuring of animals killed. The native 

 clubbers formerly selected seals for kiUing according to their appear- 

 ance; they recognized the 3-year-olds from certain characteristics. 

 Now they try to kill accordmg to size, regardless of age; that is, under 

 the present system" animals are not classed as 3-year-olds if they 

 measure in a 2-year-old or 4-year-old class. 



BULLS 



A census was again taken of harem and idle bulls. Harems on 

 portions of all rookenes were counted. Some areas on practically all 

 large rookeries had to be estimated. The result should be a fairly 

 accurate but conservative estimate of the number of breeding males 

 on hand. Owing to the cool weather, harems were not badly broken 



