do untagged pups. The first factor was believed 

 to be eliminated by experience in counting. 

 At least it can be measured in future years. 

 The second factor is more serious and is the 

 most difficult to eliminate. At the time of 

 tagging, some of the pups are resident at the 

 water's edge or are spending most of their 

 time in the water. When pups are rounded 

 up for tagging, those near or in the water 

 escape and are not tagged. Pups that escape 

 tagging subsequently escape inclusion in the 

 sample counts. Thus, pups available for tagging 

 are the pups counted for determining tag 

 ratios. 



SEAL-PUP WEIGHTS 



Beginning in 1957, seal pups have been 

 weighed annually on St. Paul Island approxi- 

 mately one week after tagging. Table 38 lists 

 the mean weights in kilograms of tagged and 

 untagged males and females from 1957 through 

 1962. Appendix tables 26, 27, and 28 list the 



tag numbers and corresponding weights of the 

 tagged pups, by rookery and by sex. 



The main objective of the weighing program 

 is to determine if there is a relationship 

 between mean weights of pups and returns of 

 the year class. An additional 3 to 5 years of 

 data are necessary before this relationship 

 can be determined. However, data through 

 1961 showed that the mean weight of tagged 

 pups generally was less than that of untagged 

 pups. Consequently, the weighing program was 

 modified in 1962 to include three weighing a 

 month apart, the first about 1 week after 

 tagging. The purpose of additional weighings 

 was to determine if differences in weights of 

 tagged and untagged animals changed by the 

 time pups leave the island. 



The data from 1962 (table 39) show that the 

 mean weight of untagged pups for each weighing 

 period is greater than that of tagged pups. The 

 mean weight of untagged pups was significantly 

 greater than that of tagged pups for seven of 

 the eight comparisons within rookeries at the 



TABLE 38. — Mean seal-pup weights-'- approximately one week after tagging, 



St. Paul Island, 1957-62 



[In Kilograms] 



Numbers in parentheses are the number of pups in each sajnple, 

 ^ Mean weights from first weighing. 



46 



