Table 20. — Estimates ■"■ of the pup population at the time^ of shearing or tagging, from marked-to- 

 unmarked ratios, year classes 1961-65, St. Paul Island 



Fiookery 



Year classes 



1961^ 



1962^ 



1963'' 



1964"^ 



iges"* 



Reef, Gorbatoh, Ardiguen.. 

 Polovina, Polovina Cliffs. 



Little Polovina 



Vostochni, Morjovi 



Tolstoi 



Little Zapadni 



Zapadni, Zapadni Reef 



Lukanin, Kitovi 



Number 



85,700 

 21,600 

 7,500 

 47,<;00 

 3<i,800 

 18, 900 

 38,000 

 22, 100 



Number 



52,800 

 22,900 

 7,200 

 36,700 

 19,300 

 19,200 

 33,600 

 11,900 



Number 



55,600 

 23,800 

 6,500 

 52,000 

 23,600 

 20,000 

 32,400 

 16,000 



Number 



65, 100 

 27,400 

 8,400 

 59, 800 

 25,400 

 17, 100 

 39, 900 

 19,200 



Number 



51,800 

 23,300 

 7,000 

 51,900 

 26,800 

 15,300 

 32,500 

 17, 100 



Total 276,000 



203,600 229,900 262,300 225,700 



■"■ The estimates for some rookeries have been combined so that the estimates for each year are 

 conp arable. 



^ Estimates do not include pups that died before shearing or tagging. 

 ^ Pups marked by tagging. 

 '^ Pups marked by shearing. 



REPRODUCTION 



The testes of 250 seals were collected onSt. 

 Paul Island in June and July incidental to a 

 study of the age composition and territorial 

 behavior of harem bulls. Tissue sections have 

 been cut and stained with periodic acid Schiff's 

 reagent. Variation in diameter of seminiferous 

 tubules and in abundance of sperm are being 

 studied. No investigation of spernnatogenesis in 

 the fur seal has been made in the Bureau's Ma- 

 rine Mammal Biological Laboratory, though 

 Kenyon, Scheffer, and Chapman (1954) reported 

 on the age of males at sexual nnaturity and the 

 potency rate among adults. Their information 

 was obtained from collaborators. 



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

 4-year-old females taken in the kill 23-27 

 August on St. Paul Island were collected and 

 preserved for later study. None of the 3-year- 

 old fennales had given birth; one 4-year-old was 

 primiparous and recently post partum. This 

 sample is not necessarily representative of all 

 3- and 4-year-old females. 



Thirty-one fennales were marked prior to, 

 or just after, copulation or parturition and 

 were killed at various dates thereafter . Physi- 

 ological changes in their ovaries will be 

 studied as an aid in interpreting the reproduc- 

 tive condition of fennales sannpled from the kill. 



OTHER STUDIES 



This section contains brief descriptions of 

 experinnental procedures or special studies 

 not discussed in the foregoing sections. Sub- 

 jects discussed include experimental skins, 

 radionuclides in seal teeth, seal behavior, and 

 rookery charts. 



Experimental Skins 



Skins of 517 fennales and 361 males were 

 collected on St, Paul Island to connplete a 

 collection begun in 1963 for a study of the 

 relation of sex and age to the connnnercial value 

 of sealskins. Skins collected for experimental 

 use since 1958 are listed in table 2 1 , In addi- 

 tion, 25 skins fronn males and 25 fronn females 

 were collected for a study of sealskin quality 

 being conducted by the North Pacific Fur Seal 

 Connmission, and 8 skins from nnales and 7 

 fronn females were sent to Japan, 



In conference with a fur processor, a proce- 

 dure was developed for nnaintaining the identity 

 of experinnental skins throughout the involved 

 steps of factory processing. By this method, the 

 nunnbered plastic tube tag originally fastened 

 to each fresh skin on the killing field is re- 

 placed at the factory by a perforated symbol 

 applied to the cheek of the salted skin. Through 



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