Table 14. --Summary of tag loss for male seals tagged as pups, tag series O through S, Pribilof Islands, 



Alaska 



Total 



2.469 1,620 



4, 089 



0.40 



670 



212 



882 



0. 24 



Total 



1, 634 



885 



2, 519 



0. 35 



442 



131 



573 



0.23 



Total 



1,928 



890 



2,818 



0.32 



508 



146 



654 



0.22 



1966 

 S 



35 



22 



57 



0. 39 



10 



16 



0. 62 



1_/ No R-series tags were applied to seals on St. George Island. 



(P<0.001) for tags applied to pups in September 

 than for those applied in August (table 16). 

 Because there is very little natural mortality 

 of pups on land between mid-August and late 

 September, we assume that the difference in 

 recovery rate was caused by the difference in 

 the age of the pups at the time of tagging. 

 Consequently, we have scheduled all of the pup 

 tagging on St. Paul Island in mid-September or 

 later since 1966. We have continued to tag pups 

 on St, George Island in August because trans- 

 portation to the island is unavailable later. 



Tags VS. Other Marks 



Cattle-ear tags, when attached to pups, 

 apparently cause an increase in mortality for 

 that group of animals. The magnitude of the 

 mortality, however, is unknown. 



As it is nearly impossible to measure 

 directly the effect of tagging on survival, other 



methods of marking believed to be less harm- 

 ful were tried in 1965 to see if they would give 

 comparable results. We used different marks 

 on three groups of about equal numbers of pups. 

 We attached a single cattle-ear tag to the left 

 front flipper of each of 10,000 pups and cut a 

 V-notch checkmark into the leading edge of the 

 same flipper near the tip. We also marked 

 10,007 pups by cutting a V-notch into the lead- 

 ing edge of the right front flipper near the tip 

 (RFV), and marked 10,080 by removing the 

 tip of the first digit on the right hind flipper 

 (RHl). Pups were given similar tags and marks 

 in 1966. Examples of tag and mark locations 

 are shown in figure 9. 



Animals given tags and checkmarks in 

 1965 and seals given marks only in that year 

 were recovered at age 2 in 1967 (Marine 

 Mammal Biological Laboratory, 1970) and 

 at age 3 in 1968 (table A-3Z). Of the 2-year- 

 old males killed in 1967 from the three groups. 



15 



