the fifth successive year--from 28,286 in 1961 

 to 16,804 in 1966, Harem males on the rookeries 

 in 1966 approximated 71 percent of the number 

 counted in 1961, and idle males were 47 per- 

 cent. Counts of adult males are given in 

 tables A-lO to A-12. 



REPRODUCTIVE CONDITION 

 OF FEMALES 



The genital tracts of 65 3-year-old and 51 

 4-year-old females killed 23-27 August 1965 

 on St. Paul Island were examined for evidence 

 of parturition in 1965, and the ovaries were 

 sectioned to reveal developing corpora lutea 

 and other indicators of sexual maturity de- 

 scribed by Roppel, Johnson, and Chapman 

 (1965), Of the ll6 females examined, one 

 4-year-old was primiparous and recently post 

 partum; the remaining 4-year-olds and all of 

 the 3-year-olds were nuUiparous (table 7), If 

 we assume that a developing corpus luteum or 

 a Graafian follicle at least 5 mm, in diameter 

 indicates sexual maturity (Craig, 1964), then 

 46 percent of the 3-year-olds and 59 percent 

 of the 4-year-olds in the sample of 1 16 females 

 were mature. 



WEIGHTS OF PUPS 



Seal pups have been weighed on St. Paul 

 Island annually about 1 September since 1957 

 to determine if body weight in autumn is related 



to survival. A consistent relation would be 

 useful for predicting the kill from a year class. 

 These data are discussed in the section on 

 forecasts. 



Tagged and marked pups have weighed less 

 than untagged and unmarked pups 1 or 2 weeks 

 after tagging each year in 1957-65, In 1965, 

 pups that were marked by removing the tip of 

 the first digit on the right hind flipper also 

 weighed less than untagged and unmarked pups. 



Information on the effect of handling was 

 obtained in 1966, We marked 800 pups on each 

 of two rookeries on St, Paul Island 17 august 

 by shearing a patch of fur from the rump. One 

 or two men prevented the pups from escaping 

 while three teams of two men each (one holder 

 and one shearer) worked on small groups of 

 pups driven into three-sided barricades from 

 the main group as needed. Samples of marked 

 and unmarked male and female pups were 

 weighed 13 days after marking. The mean 

 weights for each sex in each sample were less 

 for marked (handled) pups than for unmarked 

 (unhandled) pups (fig. 12 and table A- 13). A 

 combined probability test of sexes and rook- 

 eries showed that handled pups weighed sig- 

 nificantly less than unhandled pups (P<.05), 



Tagging, marking, and handling, individually 

 or combined, causes a loss of weight or slows 

 the normal rate of weight gain. Loss of weight 

 may cause tagged or marked pups to die at a 

 greater rate than untagged and unmarked pups 

 during their first winter at sea, thus inflating 

 later estimates of the population based on re- 

 coveries of tagged and marked seals. 



Table 7. --Ovarian activity of 3- and 4-year-old female seals, St. Paul Island, 1965 



Age Postovulation— Preovulation 



2/ 



Active — 



Inactive — 



Total 



Years Number Percent Number Percent Number Percent Number Percent Number 



1/ Evidence of ovulation based on a developing corpus luteum in one ovary. 



2/ One or more Graafian follicles each 5 mm. or larger in diameter. Measurements were taken 

 after the ovaries were sectioned. 



3/ Both ovaries with Graafian follicles, all less than 5 mm. in diamieter. 

 4/ One or both ovaries without Graafian follicles. 



13 



