250 NORTH AMERICAN FAUNA 74 



Table 42. Percentages of animals in groups of different sizes in relation to time. 



Group type 

 and time 



No. ot 

 animals 









Group 



size 









1 



2 



3-4 



5-9 10-15 



16-35 36-96 



>96 



All-male 





















February-April 



428 



18 



14 



24 



21 



6 



17 



0 



0 



May-June 



382 



4 



1 



1 



8 



3 



5 



0 



78 



Females and young 





















February-April 



1,940 



1 



7 



6 



9 



9 



28 



24 



16 



May- June 



1,054 



1 



6 



2 



4 



3 



8 



19 



57 



I have attempted to reconstruct the Pacific walrus population about the years 

 1960 and 1972, drawing on data from several sources. 



Population in 1960 



In September-October 1960, during an aerial census of the w^alrus population 

 in the western Chukchi and Bering seas, Fedoseev (1962) noted that herds of 

 adult males were easily identified by their pale, pinkish color, in contrast to the 

 darker, browner coloration of herds made up mainly of adult females and young 

 of both sexes. On that basis, he determined that the number of individuals in all- 

 male herds made up 32% of the animals in Soviet waters. In the same area, in 

 August-September 1961, Krylov (1968: Table 4) determined from shipboard 

 counts of some 30,000 individuals that the animals in all-male herds made up 

 about 42% of the total. This proportion is different from that provided by 

 Fedoseev, but the imprecision inherent in both samples is such that they are ac- 

 ceptably similar as "rough estimates." Krylov's counts indicated that 43.5% of 

 animals in all-male herds in Soviet waters were in the Bering Sea (Gulf of 

 Anadyr), and 56.5% were in the western Chukchi Sea. 



In September 1960, Krylov (1966a) estimated visually that 8 to 10% of the 

 males using the Rudder Spit hauling ground in the Gulf of Anadyr were imma- 

 ture individuals "not more than 3 years old." His criterion of "tusks reaching 

 20 cm," however, indicates that they actually were up to 5 years old (cf. 

 (Fig. 81). Gol'tsev (1968) determined the age of 348 males harvested on Rudder 

 Spit between 1937 and 1956 and found that 14% were up to 5 years old, 

 43% were 6 to 9 years, 27% were 10 to 14 years old, and 16% were more than 

 14 years old. He suspected that the sample was biased by selection of young 

 animals, but he apparently was unable to confirm that. Hence, this is the best 

 estimate available of the age composition of the Rudder Spit herd, and of males 

 summering in the western Bering Sea, at that time. 



The all-male herds in the Chukchi Sea, according to Krylov (1966a), were 

 composed of 40% immature animals under 6 years old in 1960. Conversely, the 

 age composition of males harx ested in that area in 1960 to 1964, as depicted by 

 Fedoseev and Gol'tsev (1969), indicated 1 to 8% under 6 years, 4 to 16% 6 to 

 9 years old, 23 to 48 % 10 to 14 years old, and 34 to 61 % 15 years and older. The 

 compositions of these harvests presumably were biased by selective taking of the 

 largest animals, but they suggest at least that the all-male herds in the Chukchi 



