2 3 4 5 



AGE (YEARS) 



a mane (see glossary) found on the hauling 

 grounds of St. Paul Island were killed, and 20 

 percent of the animals were sampled for age 

 and body length. These measurements, all of 

 which were taken within the period 17-26 July, 

 should represent an unbiased sample of lengths 

 for all males killed except 5-year-olds. Some 

 5-year-olds are allowed to escape because they 

 are too large for the market. 



We have measured males to determine if 

 their body length varies from year to year and 

 to establish any trends that might exist. We 

 are also studying other relations involving 

 length. 



The mean body length by age for seals of 

 most ages increased from 1964 to 1968, then 

 decreased in 1969 (table 37) . The increase was 

 most pronounced in 1967 and 1968, and the 

 mean body length varied from year to year, 

 probably in reflection of changes in the environ- 

 ment. We need additional data, however, be- 

 fore we can determine if a trend in length 

 exists or if length is related to population size 

 or survival. 



Ancel M. Johnson 



Figure 12. — Weights of bacula, male seals ^ 2 years 

 old, St. Paul Island, 22-26 July 1968. Horizontal 

 lines = mean ; black vertical bars = mean to ±2Sx; 

 open vertical bars = mean ± 2S ; vertical lines 

 = range; X = outliers. Numbers in parentheses 

 represent sample sizes. 



Table 34. --Mean body lengths— of female seals, St. Paul Island, 

 North Pacific Ocean, t/and Bering Sea, by month, 1968 



[Numbers in parentheses show sample sizes] 



1/ Tip of nose to tip of tail. 



2/ Two seals were collected off Southeastern Alaska and 33 

 were taken in and between the Gulf of Alaska and Unimak Pass. 



31 



