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Figure 4. The harem—bull count. General Manager 
Clarence L. Olson counting harem bulls on Reef rookery at the 
height of the pupping season, 15 July 1949. Towers and walk- 
ways provide safe vantage points for the observer. The pole 
is carried both as an aid in counting and to ward off charging 
bulls. Painted numbers on the rocks define boundary areas to 
aid the counter and identify camera stations (VBS 2620). 
Fecundity of bulls 
From the observations noted in appendix B, the suggested pattern 
of maturity of the males is as follows: The male seal produces spermatozoa 
at age 3 or 4, is sexually mature at age 5 or 6, begins to breed at age 7 
to 9, and attains the status of a peak-of-the-season breeder, or harem 
master, at about 12 to 15. Judging from their worn teeth, many large harem 
masters may be at least 20 years old. Three branded males 18 years old were 
seen in 1938 holding large harems (U. S. Bureau of Fisheries, 1938, p. 163). 
While the foregoing is the probable pattern, it does not exclude the possi- 
bility that some 6-year-olds breed, or that some bulls are fully prime by 
age 10 or ll. 
On the basis of population estimates, about 46 pups are born for 
each organized harem counted on the Pribilof Islands in mid-July. This 
does not mean that, on the average, each counted harem bull fathers 46 pups. 
The mid-July bull may occupy a territory which will be occupied later in 
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