Table 43. — Tag recoveries from fur seals collected 

 pelagically in the eastern North Pacific by the 

 United States in November and December 1967, and 

 January, February, May, June, July, and Augiist 1968. 



[Figures in parentheses indicate number of animals that 

 had lost tags; these are included in the totals. Seals 

 that were marked only axe included in tagged seal 

 totals.] 



Table does not include seals bom in years when 

 seals were not tagged, nor year classes from which no 

 tagged seals were taken. 



Animals tagged as 2-year-olds, based on body length. 

 Samples were collected from January to April 

 from California to Southeast Alaska, from April 

 to June in Yakutat and the Gulf of Alaska, and 

 from May to October in western Alaska, Unimak 

 Pass, and the Bering Sea (table 44). The tests 

 were restricted to seals 5 years oldandolder, 

 because younger seals have very low pregnancy 

 rates and thus are not important to the breeding 

 population. Ages 5, 6, and 7 were tested sep- 

 arately, because the percentage of females 

 pregnant differ for those ages (38, 73, and 81 

 percent, respectively). The pregnancy rates for 

 females 8 to 1 3 years old are similar (fig. 20). 

 An analysis of variance test of the pregnancy 

 rates (transformed by arcsin) by year, showed 

 no significant differences between ages or 

 years for females 8 to 1 3 years old (P > O.ZS). 

 According to a testfor nonadditivity, the trans- 

 formed data were additive (P>0.25). Ages 8 to 

 13, therefore, were pooled (mean pregnancy 

 rate of 89 percent). Females 14 years old and 

 older were pooled to increase sample sizes 

 and to minimize the effects of errors known to 

 exist in assigning ages to older animals. Chi- 

 square was used to test for significance be- 

 tween nun-ibers of pregnant and nonpregnant 



seals (P<0.05 indicates significant differ- 

 ences). Comparisons were limited to sannples 

 of 15 or n-iore seals. 



Five-year-old seals had significantly dif- 

 ferent pregnancy rates in the different areas in 

 3 to 4 years when areas within years were 

 tested (0,01<P<0.05, table 45). The pregnancy 

 rates for females in ages 6, 7, 8 to 13, and 

 >14 were similar when areas within years were 

 tested (P>0.05). Why oruy age 5 seais differed 

 is not knowm. 



When different years within areas were 

 tested by chi-square, the pregnancy rates of 

 seals collected off California were significantly 

 different for all age groups except age 7 (table 

 46). Pregnancy rates for age groups other than 

 7 were low in 1964 and 1965 and high in 1958 

 for samples collected off California, Samples 

 from California were collected in April- May 

 1964 and 1965 as opposed to January-April in 

 the other years. Age 5 seals were collected 

 during similar months off California in 1958, 

 1959, 1961, and 1966, but the pregnancy rates 

 were not as high in 1961 and 1966 as in 1958 

 and 1959 (24-27 percent in 1961 and 1966 as 

 compared to 60 percent in 1958 and 1959). If 

 pregnant seals had already left the area off 

 California to migrate to the Pribilof Islands 

 before samples were collected in 1964 and 

 1965, then we would expect lower pregnancy 

 rates. Nonpregnant seals may migrate to the 

 Pribilof Islands later in the year than preg- 

 nant seals, or in some years may not return 

 at all. 



Pregnancy rates for seals in ages 8 to 1 3 

 collected in western Alaska in 1958, 1960, 

 and 1962 were significantly different (P;0.01); 

 the pregnancy rate in 1960 (96.7) was higher 

 than the rate in 1958 (87.8) and 1962 (83.9). 

 Pregnancy rates between years for 5-, 6-, 

 and 7-year old females were similar within 

 each age group for samples collected in the 

 Bering Sea; pregnancy rates for females 8 to 

 13 and > 14 years old were significantly dif- 

 ferent (P-0.04 and P:0.01, respectively). The 

 pregnancy rate was low in 1964 for seals 8 to 

 13 and^l4 years old collected in the Bering 

 Sea. 



It is difficult to explain the cause of the 

 difference between years when the months of 

 collecting are the same. If the difference is 

 not real, possible explanations are sampling 

 errors, errors in assigning ages, and segrega- 

 tion by reproductive condition. 



Pregnancy rates varied more than we ex- 

 pected between areas, years, and months of 

 collection. Pregnancy rates differed more for 

 samples collected in different years in a 

 particular area than for those collected in the 

 same year but in different areas. The dif- 

 ferences in the pregnancy rates indicate at least 

 partial segregation of females at sea, within 

 age by reproductive condition, and by age and 

 month. No evidence exists that there has beena 



47 



