POPULATION ESTIMATES 



The number of pups born on the Pribilof 

 Islands, estimated from tag recoveries, has 

 steadily decreased irom 643,000 in I960 to 

 440,000 in 1964. 



Shearing of live pups and later sampling 

 for marked-to-unmarked ratios yielded an 

 estimate of 380,000 pups born on the Pribilof 

 Islands in 1966. The estimates and total counts 

 of pups on three rookeries were similar. 



On the basis of tagged seals taken in 1963- 

 66, an estimated 78,000 males from each of 

 two year classes (1961 and 1962) survived to 

 age 1. 



FORECAST OF THE KILL OF MALES 



The predicted kill of males on St. Paul 

 Island by 5 August 1966 included 26,000 of 

 age 3 and 14,000 of age 4; actual kills were 

 25,520 and 12,149. 



The forecasted kill of male seals on the 

 Pribilof Islands in 1967 includes 4,000 of ages 

 2 and 5, 34,300 of age 3, and 17,900 of age 4, 



SPECIAL STUDIES 



Age Composition, Measurements, and 

 Mortality of Territorial Male Fur Seals 



The age compositions of 249 territorial males 

 killed for study and 157 adult males found 

 dead were similar. The territorial males 

 were 7 to 17 years old; 71 percent were in 

 ages 10 through 13; the predominant age was 

 10. 



The annual replacement rate for territorial 

 males age 10 and older is estimated as 0.38. 

 Body length and weight of the baculum, testes, 

 and body showed no relation to age, nor was 

 there a relation between weights of the baculum 

 and testes. Body length and baculum weight 

 may be related. 



Implantation of the Blastocyst in Fur Seals 



Of 70 genital tracts of adult females collected 

 at about 6-day intervals from 13 September 

 to 28 November 1965, 17 contained an implan- 

 tation chamber. The earliest was observed 

 4 November; all five tracts collected on 28 

 November had implantation chambers. 



Errors in Determining Ages of Fur Seals 

 from Canine Teeth 



Canine teeth collected from seals of known 

 age were examined by four readers. For whole 

 teeth from males in ages 2 to 5, the lowest 

 reader error ranged from 2.5 to 3.9 percent; 

 for sectioned male teeth, the lowest error 

 was 0.0 to 6.7 percent. The lowest error in 

 determining the ages of females from whole 

 teeth in ages 3 to 7 was 3.8 to 21.3 percent. 

 A conference reading by four readers of sec- 

 tioned teeth from females in ages 2 to 1 1 pro- 

 duced errors ranging from 3.3 to 66.7 percent. 



Comparison of Ages Assigned to Fur Seals 

 by Japanese and U.S. Biologists 



Possible differences between Japan and the 

 United States in determining the ages of seals 

 were tested by exchanging samples of canine 

 teeth each had collected from seals taken at 

 sea in 1964. For teeth prepared by the Japa- 

 nese, readers from the two countries dis- 

 agreed on about 3.5 percent of 128 males in 

 ages 1 to 4 and on 4.4 percent of 204 females 

 in ages 1 to 7. For teeth prepared by U.S. 

 biologists, the readers disagreed on 2 of 1 1 

 males in ages 2 to 3 and on 36.5 percent of 

 91 females in ages 1 to 7. 



Drug Immobilization of Fur Seals 



Succinylcholine was found to be too iinpre- 

 dictable in its effect on adult male fur seals 

 for safe use. 



Nutrition of Fur Seal Pups 



Two variations of an articial formula were 

 fed for 5 weeks to two groups of four newborn 

 pups. The use of a combination of calcium 

 caseinate and fish flour as the source of 

 protein produced greater and more rapid 

 weight gains than did fish flour alone. 



Analysis of Fur Seal Milk 



Six samples of fur seal milk from different 

 stages of lactation were analyzed for gross 

 composition, fatty and amino acids, and nitro- 

 gen distribution. Colostrum milk obtained 

 immediately post partum contained much 

 higher levels of albumin and globulin than did 

 milk collected later in lactation. High levels 

 of albumin and globulin are presumed to in- 

 dicate antibody transfer through the milk. 



ACKNOWLEDGMENTS 



The research staff had the cooperation of 

 C. Howard Baltzo, Program Director; Howard 

 Euneau, St. Paul Island Manager; Roy D. Hurd, 

 St. George Island Manager; Bertel W. Johnson, 

 Management Staff Officer; Roy L. EUerman, 

 Program Engineer; and Richard A. Hajny, 

 Wildlife Management Biologist, Pribilof 



Islands. Others who cooperated were Lee 

 Paola, Superintendent, Oregon- Alaska Marine 

 Products; Iliodor Merculief, President, St. 

 Paul Island Community Council; Victor 

 Misiken, Sealer III Foreman; and Alex Melo- 

 vidov, Sealer I Foreman. 



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