ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



253 



Table 43. Estimated composition of the Pacific walrus population in I960.'' 



Age class (years) 



Sex aiid 

 locality 



Herd 

 type 



0-5 



6-9 



10-14 



>14 



Total 



Males 



W. Bering 

 W. Chukchi 

 W. Chukchi 

 W. Chukchi 

 E. Bering 

 E. Chukchi 

 Total 



Females 



W. Chukchi 

 W. Chukchi 

 E. Chukchi 

 Total 



All-male 



All-male 



Mixed 



Female 



All-male 



Mixed 



Mixed 



Female 



Mixed 



1,020 



3,125 



1,960 



1,160 



7,265 



755 



1,510 



3,395 



3,775 



9,435 



1,230 



610 



1,285 



645 



3,770 



1,605 



0 



0 



0 



1,605 



240 



330 



930 



1,500 



3,000 



390 



210 



420 



210 



1,230 



5,240 



5,785 



7,990 



7,290 



26,305 



0-5 





>5 







1,015 





4,415 





5,430 



4,825 





13,670 





18,495 



330 





1,440 





1,770 



6,170 





19,525 





25,695 



^Numbers of animals based on the estimate of 46,000 in Soviet waters (Fedoseev 1962) 

 and assumption of 6,000 in Alaskan waters in late summer. 



St. Lawrence Island and in Bristol Bay. Around each concentration were large 

 areas containing widely scattered individuals and small groups (Fig. 138). From 

 aerial photographs taken during that survey by D. A. Borchert and from 

 observations made during three expeditions on icebreaking vessels in those high- 

 and low-density zones, 3,344 animals were classified by sex and relative age 

 (Table 44) . At least 90 % of the males in the high-density zones were judged to be 

 mature (> 14 years), whereas only about one-third of those in the low-density 

 zones were mature. In a random sample of 116 males from the Bristol Bay low- 

 density zone in March-April 1976, males 15 years old and older made up 37% 

 (V. N. Gol'tsev and F. H. Fay, unpublished data). Counts of 853 females and 

 young, mainly in the areas of high density, indicated that 507 (59%) were 

 females of breeding age and 346 (41%) were immature animals of both sexes, 

 presumably with a 1:1 sex ratio (F. H. Fay, unpublished data). 



Applying the above proportions and those in Table 44 to Kenyon's (1972) 

 regional estimates of walrus numbers, a population with the following composi- 

 tion is inferred: 



• In the St. Lawrence high-density zone, the total number of animals was 

 estimated as 59,280. Of those, about 6% (3,560) were males 10 years old and 

 older and 94 % (55,720) were adult females and immature animals of both sexes. 

 Of the males, 10 % (360) were under 15 years old and 90 % (3,200) were 15 years 

 and older. Of the females and young, 41 % (22,840) were immatures of both 

 sexes and 59% (32,880) were adult females. 



• In the St. Lawrence low-density zone, the total number of animals was esti- 

 mated at 14,220. Of those, about 96% (13,650) were males 10 years and older 



