Table 13. — Slant depth of the f\xr seal dermis by age, sex, and molt 



(frequently distribution) . — Continued 



Depth of dermis 



Age in years 



0^ 



4 



>52 



Total 



Mm. 



2.5 1 



3.0 



3.5 2 



^.0 6 



4.5 



5.0 1 



5.5 



6.0 



6.5 



7.0 



7.5 



8.0 



Total 10 



Female, molting 



20 



18 



13 



27 



99 



"'• Black pups and silver pups combined. 



^ Mean age of 133 nonmolting old females 11.38 years; of 27 molting old 

 females 11.15 years. 



grows to adulthood. While the blubber is 

 distinct from the layer of dermal fat cells, 

 the metabolism of the two fat depots is pre- 

 sumably linked, and changes in one layer are 

 reflected in the other. 



Change in the Sebaceous Gland 



The cross-section width of a large sebaceous 

 gland on each of 52 cross-section mounts 

 representing 52 seals (table 14) ranged from 

 75 to 350 microns with a mean of 198 microns. 

 The two largest measurements (307 and 350 

 microns) are from a 12-year female in August 

 and a 15 year female in January, both in 

 beginning molt. Although there is some indica- 

 tion of an increase in the width of the gland 

 with age and molt, the data are highly variable 

 and are insufficient for some year classes to 

 show the exact relationship. 



Change in Weight 



The weight data are from a small but fairly 

 homogenous group: 429 females, not obviously 

 pregnant, older than 10 years. The results are 

 given in table 15 and figure 9. They suggest an 



increase from about 32 kg. in January to 44 kg, 

 in June, during a period when seals are pelagic. 

 A sharp dip in April, observed in the data 

 both for 1958 and 1959, is unexplained. A June 

 sample taken at sea has, perhaps by chance, 

 the same mean weight as an overlapping 

 sample taken on land. After June, the weight 

 drops slightly. It fluctuates between 39 and 42 

 kg. until November. While no sample was taken 

 in December, the trend is quite surely down- 

 ward during this month. 



The mid-date of molt for older-than- 10-year 

 females is late November or early December 

 (by extrapolation from table 6). This is the time 

 when body weight is declining, but it is also the 

 time when seals are subjected to cold, stormy 

 weather at sea. The relative importance of the 

 two factors, molting and weather, cannot be 

 evaluated from the data at hand and therefore 

 the relationship of molt to weight fluctuation 

 is not clear. 



COMPARISON OF PELAGE, MALE AND 

 FEMALE, BACK AND BELLY 



The adult female pelt tends to be scarred, 

 presumably from the bites of other seals. And 



28 



