Table 15. — Change in body weight of the northern fur seal female by 



month''- 



Jan. 



Feb. 



Mar. 



Apr, 



May 



June 



Mean weight 

 kilograms 



Number in 

 sample 



Soiirce of 

 data 



32.4 37.8 38.8 3-4.3 39.9 A3. 6 



68 



63 



(') (') (' 



35 



34 



12 



(2) (') (') 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Mean weight 

 kilograms 



Number in 

 sample 



Source of 

 data 



43.7 40.3 38.9 41.7 40.5 40.5 



49 



57 



46 



23 



28 



(3) {') {') {') (^) (^; 



■'• Based on 429 mature animals, age 11 years or older, not pregnant 

 (or if pregnant, with embryo of microscopic size). 



2 Seals taken at sea (Wilke, Niggol, and Fiscus, 1958, p. 46 and 96; 

 Niggol, Fiscus, and Wilke, 1959, p. 33 and 85); mean age 14.9 years. 



^ Seals taken on land (data from field cards for Pribilof Islands, 

 1953). 



^ Seals taken on land (data from field cards for Pribilof Islands, 

 1961) . 



the adult female pelt tends to lose fur, espe- 

 cially from the belly, during the unhairing 

 process in the finishing factory. Aside from 

 scarring, the factors which depreciate the adult 

 female pelt are virtually unknown. Some are 

 perhaps chemical or physiological as, for 

 example, varying concentrations and kinds of 

 oils in the dermis. Others are perhaps tech- 

 nological, related to the fact that only since 

 1956 have processors been faced with the new 

 problem of finishing adult female pelts by the 

 thousands. Still other factors might be related 

 to differences in fiber size and distribution, 

 or thickness of skin. In a search for such 

 differences, skin samples from the back and 

 belly of 21 seals were examined (see technique 



^ 



JAN FEB MfiR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 

 N! 7 68 63 35 34 61 57 46 7 23 28 7 



Figure 9. --Change in body weight of the female by 

 month, based on 429 mature animals, age 11 years or 

 older, not pregnant. 



30 



