60 

 50 

 40 

 30 



mZO 



10 



— MALES X = 93 6 



— FEMALES y=9l. 



I r I — I I I I I I I 

 82 8<» 86 88 90 92 94 96 98 100 102 

 LENGTH (CMO 



Figure 8.- -Distribution of body lengths among 

 839 selected yearlings, St. Paul Island, 1962. 



82 84 86 88 90 92 94 96 98 100 102 104 

 LENGTH (CMJ 



Figure 9. --Distribution of body lengths among 

 134 known-age yearlings, St. Paul Island, 1962. 



MALES 



82 84 86 88 90 92 94 96 98 100 102 104 106 



SELECTED YEARLINGS 



— KNOWN-AGE YEARLINGS 



82 84 86 88 90 92 94 96 98 100 102 104 106 

 LENGTH ICMJ 



Figure 10.- -Body length comparisons of selected and 

 known-age yearlings, St. Paul Island, 1962. 



Details on the recovery in 1962 of yearling 

 fur seals tagged as pups in 1961 are given in 

 table 19. Homing tendency of known-age year- 

 lings (table 20) was determined as the percent 

 recovered on the rookery of tagging or birth. 

 An average of 80 percent of the known-age 

 yearlings observed in 1962 returned to the 

 rookery of tagging or birth. Sixteen known-age 

 yearlings were observed in 1961; 12 or 75 

 percent had returned to the home rookery. 



Discussion . — Experience in 1962 indicates 

 that yearlings appear earlier in the fall than 

 expected. Yearlings became abundant enough 

 by the third week of September for tagging 

 operations to begin, whereas, formerly it was 

 believed that few arrived before mid-Oc- 

 tober. 



The likely reason for the discrepancy 

 between sex ratios for the years 1941 and 

 1962, and 1961 is that of misidentification and 

 tagging of 2-year-old females in 1961. Use of 

 body length rather than weight as a criterion 

 of age in 1962 may have eliminated error in 

 identification of yearlings. 



It was also thought in 1961 that yearlings 

 could be distinguished from 2- and 3-year-old 

 seals by the light colored under fur on the 

 back region. But it was found that some 

 marked yearlings had dark colored underfur. 

 From the practical standpoint, seals were 

 sometimes so covered with rookery mud that 

 it was difficult to determine the underfur 

 color. 



Although only 967 yearlings were tagged in 

 7.5 days, twice this number could have been 

 handled if a larger and more efficient crew 

 had been used. Three days of tagging each 

 week would preferable to five, since all the 

 rookeries can be visited and tagging com- 

 pleted in 2 days. A short interval of time is 

 needed for new arrivals to accumulate and 

 for overlooked or escaped yearlings to re- 

 turn. 



A period of 1.5 months (the approximate 

 duration yearlings are present on the islands) 

 would be needed to tag 5,000 yearlings. 



28 



