TABLE 12. — Annual variation in pregnancy rates of females sampled 

 from the kills ^ Pribilof Islands, Alaska, 1956-62 



"*• Tagged and untagged females have been combined. 

 ^ Tagged females only were examined. 



group, either by means of a noose attached 

 to an 8-foot pole, or a lasso. Selected seals 

 were dragged to a tagging site, preferably a 

 level area. After removal of the noose or 

 lasso, the animals were restrained in a 

 straight, flat position so their body lengths 

 could be measured (fig. 6). Tags were at- 

 tached to the front flippers (fig. 7) of females 

 95 centimeters or less in length and to males 

 100 centimeters or less in length. 



Maximum acceptable length limits for tag- 

 ging yearlings were derived from information 

 obtained from measurements of known-age 

 yearlings taken in 1941 and in 1961. Visual 

 selection of "yearlings" in 1962 was based 

 primarily on body size and pelage coloration. 



Results . — The number of selected yearlings 

 tagged in 1962 is given, by rookery, in table 

 1 7. Sex ratios among selected and known-age 



yearlings for 1941,* 1961, ^ and 1962 are given 

 in table 18. The discrepancy in sex ratios 

 between known- age and selected yearlings for 

 1961 is discussed later. 



Distribution of body lengths for selected and 

 known-age yearlings is given in figures 8 and 

 9. Mean body lengths of selected yearlings 

 were 93.6 centimeters for males and 91.5 

 centimeters for females, and those of known- 

 age yearlings, 94.6 and 90.3 centimeters, 

 males and females, respectively. Mean lengths 

 of 12 male yearlings recovered in 1941 were 

 95.4 centimeters and of 6 female yearlings, 

 87.1 centimeters. In 1961, the mean length 

 of five known-age male yearlings was 88.6 

 centimeters. As shown in figure 9, lengths of 

 known-age female yearlings did not exceed 



*See footnote 2, page 16. 

 5See footnote 3, page 17. 



18 



