Table 3. --Tag recoveries from fur seals collected pelagically by the U.S.A. in 1965 

 [Figures in parentheses indicate animals that had lost tags; they are included in the totals. ] 



ly Table does not include seals born in years when no tagging was done, or 

 year classes from which no tagged seals were taken. 



Reproductive condition .- -Of the females col- 

 lected off California and Washington in 1965, 

 45 percent were nulliparous, 12 percent were 

 nonpregnant primiparous and multiparous, and 

 44 percent were pregnant (tables A- 12 and 

 A- 13). The youngest pregnant females taken 

 were three primiparous 5-year-olds. 



Pregnancy rate; .- -The nunaber of female 

 seals (and the percentage pregnant) collected 

 in the eastern Pacific from 1958 to 1965 are 

 shown in table 4; records for 1965 are given 

 by area and month in table A- 14. 



Data on pregnancy rates are necessary for 

 making population estimates and for deter- 

 mining the effects of a reduction in size of the 

 herd. For example, the low pregnancy rates 

 of 3- and 4-year-old females may increase 

 now that killing of females on the Pribilof 

 Islands has reduced the herd to the approxi- 

 mate level of maximum sustained yield. Preg- 

 nancy rates representative of the population 

 cannot be accurately determined from animals 

 taken on the Pribilof Islands because the 

 females segregate by reproductive condition 

 when on land (Roppel, Johnson, Anas, and 

 Chapman, 1965). Therefore, knowledge of vari- 

 ation in rates among females taken at sea, by 

 year, season, and area, is important as a basis 

 for determining pregnancy rates representa- 

 tive of the total population. 



Regardless of area or season of collection, 

 the total annual samples show little variation 

 in pregnancy rates among females in ages 



7-13 during the period 1958-65. The variation 

 increased among 6-year-old females, and at 

 age 5 the pregnancy rate in different years 

 ranged from 21 to 56 percent (mean 39 per- 

 cent). These variations are unexplained. 



Uterine horn of conception and fetal sex 

 ratio .-- The uterus of the female fur seal is 

 bicornuate. One uterine horn carries a con- 

 ceptus one year and the other horn carries a 

 conceptus the following year unless the fennale 

 fails to conceive one or nr^ore years. Exannina- 

 tion of 5,057 pregnant females collected since 

 1958 shows that 5 1 .3 percent of the fetuses were 

 carried inthe left uterine horn. This difference, 

 together with the necessity of alternating horns 

 in order to conceive each year, means thatthe 

 first conception, or conceptions that occur fol- 

 lowing an interruption, nnust be nnost frequently 

 in the left uterine horn. 



Of 4,369 fetuses collected in 1958-65, 49.2 

 percent were males and 50.8 percent were 

 females. 



Attached Organisms (Commensals) 



Algae and gooseneck barnacles are com- 

 monly found on the guard hairs of seals that 

 have been at sea for an extended period. Of 

 270 seals collected off California in 1965, 

 algae were attached to the guard hairs of 42.2 

 percent, barnacles 33.3 percent, and both 

 algae and barnacles on 18.1 percent (table 5). 

 The amount of algae ranged from a few spots 

 to almost complete coverage of the animal. 



