ECOLOGY AND BIOLOGY OF THE PACIFIC WALRUS 



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Sea were made up of somewhat older animals than those in the Gulf of Anadyr 

 (Fedoseev and Gol'tsev 1969). 



The remainder of the herds in the western Chukchi Sea were of two types: 

 "mixed" herds, mainly of adult females and young of both sexes with a few older 

 males, and "female" herds made up only of females with young of both sexes. 

 About 31% of the animals were in mixed herds and 69% were in female herds 

 (Krylov 1968: Table 4). The mixed herds, according to Krylov's (1966a) visual 

 sample of 626 animals, were composed of about 21 % males with bosses on the 

 neck and shoulders (about 10 years old and older: Krylov 1967), 48% "adult" 

 females (6 years old and older: Krylov 1966^?), 20% immature males (under 

 10 years), and 10% immature females (under 6 years). Krylov (1966a) cited a 

 comparable sample (size not given) recorded by P. G. Nikulin in 1952 of 16.7% 

 adult males, 48.8 % adult females, and 30.3 % immature animals of both sexes in 

 mixed herds in the Chukchi Sea. 



The composition of the female herds was implied by a nonselective sample of 

 43 females taken in the Chukchi Sea in 1962 (Krylov 1968: Table 7). Of those, 

 26% were immature females (under 6 years), and 74% were breeding adults. 

 Immature males were not mentioned but must have been equal to at least one- 

 third the number of immature females, since young males also remain with the 

 mother for at least the first 2 years and are gradually recruited into all-male 

 herds over the next 4 or 5 years. 



With these proportions, a crude approximation of the composition of the esti- 

 mated 46,000 walruses in Soviet waters in summer 1960 (Fedoseev 1962) can be 

 reconstructed, as follows: 



• The animals in all-male herds made up 32 to 42 % of those counted (Fedoseev 

 1962; Krylov 1968), the mean of which is (0.32 x 39,100) + (0.42 x 30,000) = 

 25,110/69,100 = 36.3% or about 16,700 animals. 



. Of these, 43.5% (7,265) were in the Bering Sea and 56.5% (9,435) were in 

 the Chukchi Sea (Krylov 1968). 



• The composition of the Bering Sea all-male herds, according to Gol'tsev 

 (1968) was about 14% (1,020) under 6 years old, 43% (3,125) 6 to 9 years old, 

 27% (1,960) 10 to 14 years old, and 16% (1,160) 15 years and older. 



• The composition of the Chukchi Sea all-male herds, assuming that the 

 younger age classes may have been underrepresented in the harvest samples 

 (Fedoseev and Gol'tsev 1969), was about 8% (755) under 6 years old, 16% 

 (1,510) 6 to 9 years old, 36% (3,395) 10 to 14 years old, and 40% (3,775) 15 

 years and older. 



• The animals in the mixed and female herds made up 58 to 68% (mean, 

 63.7%) of the total, or about 29,300 individuals. 



. Of those, 31.4% (9,200) were in mixed herds and 68.6% (20,100) were in 

 female herds (Krylov 1968). 



• The mixed herds comprised 41% males (3,770) and 59% females (5,430), 

 according to Krylov (1966a). Of these, males less than 10 years old made up 

 about 20% (1,840), probably at least two-thirds of which (1,230) were under 6 

 and the rest (610) were 6 to 9 years. Males 10 years and older made up 21% 

 (1,930), of which probably about two-thirds (1,285) were 10 to 14 years and 

 one-third (645) was mature adults 15 years and older. Females under 6 years 

 made up 11% (1,015), and adult females 6 years and older were 48% (4,415). 



