SUMMARY 



Males 



1. Of 42,386 male seals killed on the 

 Pribilof Islands in 1963, 39,685 were taken 

 during the male kill from 2 July to 5 August 

 and 2,701 during the kill of females 13 August 

 to 12 September. St. Paul Island accounted 

 for 31,881 and St. George Island, 10,505. 

 Age classification of the kill in percent was: 

 St. Paul Island, 4, 46, 45, and 5, ages 2-5; 

 St. George Island, 9, 41, 45, and 5, ages 

 2-5. 



2. At least 3,150 male seals were taken 

 as a result of early season removal of the 

 maximum length limit of 48-3/4 inches. Ab- 

 sence of the mane, a secondary sex charac- 

 teristic evident at age 6 and older, was sug- 

 gested as a substitute for the maximum length 

 limit. 



3. The peak of the kill occurred during round 

 6 (22-26 July) when 5,809 males were taken 

 on St. Paul Island. The total kill of 18,481 

 4-year-old males by 5 August agreed closely 

 with the forecast of 18,750 for a kill ending 

 between 31 July and 15 August. A kill of 

 37,500 3-year-olds by 31 July or 50,000 by 

 15 August was predicted; 17,986 were taken 

 by 5 August. 



4. The number of bulls counted on land 

 10-17 July decreased from 12,674 harem and 

 11,759 idle in 1962 to 11,283 harem and 9,540 

 idle in 1963. 



5. From 3- and 4-year-old male data, esti- 

 mates of number of pups born on the Pribilof 

 Islands in 1958 and 1959 were 729,000 and 

 778,000. 



6. The St. Paul Island pup population in 

 1963 was estimated at 229,900 from a marked 

 to unmarked ratio obtained from shearing and 

 sampling pups in August and adjusted to 255,700 

 on the basis of a live- pup count on one rookery. 

 Exclusive of pups that died before shearing, 

 the pup population of both islands was esti- 

 mated at 316,000. 



Females 



1. A total of 43,952 female seals were 

 taken on the Pribilof Islands in 1963. The 

 female kill began 13 August, ending 12 Sep- 

 tember on St. Paul Island with a kill of 35,093 

 and 30 August on St. George Island with a kill 

 of 8,859. 



2. Reproductive studies of 310 known-age 

 3- and 4-year-old females taken on St. Paul 

 Island in 1963 were made. Two of 170 4-year- 

 olds were primiparous and had given birth to 

 their first pup in 1963; all (140) of the 3-year- 

 old females examined were nulliparous. 

 Graafian follicles in both ovaries of 307 of 

 the females indicated approaching maturity. 

 Based on the presence in one ovary of a de- 

 veloping corpus luteum or one or more follicles 



5 mm. or larger in diameter, 33 (24 percent) 

 of the 3-year-olds and 118 (70 percent) of the 

 4-year-olds would have been bred in 1963. 



3. Total pup populations estimated from 

 female data were 872,376 for the 1958 year 

 class and 859,371 for 1959. 



Tag Recoveries and Tagging 



1. A total of 3,703 tagged seals and 2,077 

 with checkmarks only were recovered in 1963; 

 37 Soviet-tagged fur seals were taken. Eighty- 

 four seals selected and tagged as yearlings 

 in 1961 and 1962 were recovered in 1963. Only 

 13 of 34 recoveries from the 1961 tagging 

 were actually yearlings when tagged; 45 of 50 

 recoveries from 1962 were yearlings when 

 tagged. Body weight was used as an indicator 

 of age in 1961, whereas length was used in 

 1962. 



2. Twenty-five thousand seal pups were 

 tagged; the tip of the same flipper was sliced 

 off as a checkmark. A total of 701 seals was 

 selected and tagged as yearlings in 1963; 98 

 that had been tagged as pups in 1962 were 

 each given an additional tag. 



3. Five weekly counts of yearlings tagged 

 as pups in 1962 were made from 27 September 

 through 11 October 1963 on 11 sampling areas 

 on St. Paul Island. These counts may pro- 

 vide an index to survival from birth to age 1 

 and a rough prediction of the return of 3-year- 

 old male seals 2 years later. 



Mortality 



1. The 1963 pup mortality on land decreased 

 to 39,239 from 53,748 in 1962. The lowest 

 count since the beginning of complete dead- 

 pup counts in 1953 was recorded in 1958. 



Seal- Pup Weights 



1. The data from year classes 1957-59 

 suggest a correlation between mean weight 

 as pups and return at age 3. 



2. Tagged pups weighed an average of 0.57 

 kg. less than untagged pups from 1957 through 

 1963. 



Related Studies 



1. Counts of live pups made each year since 

 1959 on two of three small rookery areas on 

 St. Paul Island will be discontinued because 

 of unreliability. Live-pup counts will be con- 

 tinued on one area as a check on the reliability 

 of estimates of the pup population made from 

 marked to unmarked ratios. For the same pur- 

 pose, total counts will be made of pups on 

 four rookeries. 



2. Studies of 536 skins from females showed 

 that those in ages 2-5 years have good market 



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