106 REPORT OF BRITISH COMMISSIONERS. 



With such an animal increase of 5 per cent, to the entire herd, this 

 shoukl donble in number in about every fourteen years. 



Thus, about 770,000 breeding seals should loroduce annually 100,000 

 killable males of an average age of 4 years, and still allow for a 5 per 

 cent, annual increase of the breeding seals. 



374. Adding to the assumed unit of 110,000 breeding seals, male and 

 female, the number of non-breeding seals required by Bryant's per- 

 centage estimates of loss by death of young, the following figures would 

 represent the whole number of such seals at any one time : 



Pups, just born 100, 000 



Yearlings 40, 000 



2-year-olds 85, 000 



3-year-old8 33,000 



Eiiete seals of both sexes, say 50, 000 



Total of non-breeding seals 258, 000 



375. Addiug to these the breeding seals, the wholfe number of seals 

 present, when 30,000 may be killed annually without decreasing the 

 aggregate number, would be 368,000, and pro])ortionate]y, in order to 

 produce an increase of 100,000 annually, a total luimber of 2,576,000. 



376. As a matter of opinion, based ou such information as we have 

 been able to obtain, and notwithstanding the much larger number given 

 to the islands by several of the estiifiates previously quoted, we are 

 inclined to doubt whether the whole number of seals frequenting the 

 Pribyloff Islands has ever, since the exceptional slaughter of ISiiS, 

 actually exceeded 2,000,000. There can be no possible question that 

 the actual number has been very greatly exaggerated in most of the 

 computations made. If this opinion be approximately correct, it is evi- 

 deut that an annual slaughter of 100,000 males might lead to just such 

 a continuous and cumulative decrease in total numbers as is elsewhere 

 shown to have occurred before pelagic sealing had entered into the 

 question. 



(I:^.) — Various NaUiral Indications of former Extent of Ground occupied 

 hy Seals on the Frihyloff Islands. 



377. It will be understood, that on the Pribyloff Islands all parts of 

 the surface above the reach of the waves, and not too rocky or too 

 entirely composed of loose sand, is, in consequence of the humidity of 

 the climate, naturally covered with grass, but that on the areas running- 

 back from the shore with a greater or less width, which are occupied 

 as rookeries or hauling-grounds by the seals, the constant movement 

 and passage of these animals entirely prevents any vegetable growth. 

 Thus, these resorts of seals, when seen even from a considerable dis- 

 tance, are quite distinctly marked as bare, earthy slopes. When more 

 closely examined, it is further found that the rocky projections and 

 scattered angular rocks, which are common to a greater or less extent 

 to nearly all the rookery grounds, have had the angles more or less 

 polished and worn by the constant movement of the seals over them. 

 The rocks being generally basaltic contain no very hard minerals, and 

 there being a certain proportion of silicious matter in the sand, this 

 supplies a very efficient polishing material, which is applied by the 

 flippers and bodies of the seals. Tlie polish thus imparted to portions 

 of the rocks is different from that i)roduced by wind-drifted sand in 

 being chiefly confined to points and angles, and is thus easily distin- 

 guished from it. 



