ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



255 



Table 44. Numbers of walruses in the St. Lawrence Island (SLI) and Bristol 

 Bay (BB) areas in relation to the zones of relative distributional density 

 recognized by Kenyon (1972). 



Composition per distributional density zone^ 



SLI high SLI low BB low BB high 



Sample type 



Date 



M 



FY 



M 



FY 



M 



FY 



M 



FY 



Aerial photos 



April 1972 



40 



1,131 







22 



76 



16 



507 



Shipboard 





















observations 



April 1971 



13 



319 



184 



8 



56 



7 







Shipboard 





















observations 



March 1972 



90 



817 















Shipboard 





















observations 



March 1976 











54 



19 







Totals 





143 



2,267 



184 



8 



132 



102 



16 



507 



Percentage 



within zone 



6 



94 



96 



4 



56 



44 



3 



97 



^M = subadult and adult males (10 years and older); FY (females and young) = females of 

 breeding age (6 years and older) with immature males (<10 years) and females (<6 

 years) . 



as in the 1960 population. It resembles the estimated composition of the 1960 

 population in that about 75 % of the females were of breeding age (6 years and 

 older), and about 27% of the males were mature adults (15 years and older). 

 The principal difference between the two estimates is that the overall sex ratio of 

 males to females derived for the 1960 population was near unity, whereas the 

 ratio for the 1972 population was disproportionate (Table 46). That females 

 could have been considerably more numerous than males in 1972 seems 



Table 45. Estimated composition of the Pacific walrus population in 1972.^ 



Age class (years) 



Sex and density zone 0-9 10-14 > 14 Total 



Males 



St. Lawrence high 



11,420 



360 



3,200 



14,980 



St. Lawrence low 



115 



8,600 



5,050 



13,765 



Bristol Bay low 



1,420 



5,550 



3,260 



10,230 



Bristol Bay high 



6,845 



100 



930 



7,875 



Total 



19,800 



14,610 



12,440 



46,850 





0-5 



>5 







em ales 











St. Lawrence high 



11,420 



32,880 





44,300 



St. Lawrence low 



115 



340 





455 



Bristol Bay low 



1,420 



4,080 





5,500 



Bristol Bay high 



6,845 



19,690 





26,535 



Total 



19,800 



56,990 





76,790 



'Numbers of animals based on estimate of 123,640 overall and zonal proportions derived by 

 Kenyon (1972). 



