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Page:Popular Science Monthly Volume 54.djvu/680

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POPULAR SCIENCE MONTHLY.
taken as an actual measure of such decrease. A number of other factors must he taken into consideration, and the real measure of decrease must be sought in more pertinent statistics, drawn from the breeding rookeries themselves.

We have already noted that in that portion of the period, 1871 to 1889, which falls prior to 1884, thirteen years in all, no difficulty was experienced in securing the full quota, and it may be added that this was completed not later than July 20th. A retardation of the date at which the quota can be filled is a direct indication of the degree of exhaustion of the hauling grounds. In marked contrast with these earlier years stand the conditions of 1896 and 1897, when greatly reduced quotas only were obtained, notwithstanding the unusual prolongation of the driving period.

The statement here made that the difference between the quotas of 1896 and 1897 is not an actual measure of decline in the breeding herd requires explanation. The quota of any year is dependent upon the birth rate of three years previous, killable seals being males of approximately three years of age. The difference noted, therefore, while not indicative of the actual decrease for the seasons 1896 and 1897, is a direct measure of such decrease for the seasons of 1893 and 1894, when the seals in question were born.

That the rate of decline as thus shown was greater in 1893-94 than in 1896-97 is explained by the fact that, whereas only 30,000 seals were taken at sea in 1893, 60,000 were taken in 1894; while in 1896 43,000 were taken as against only 25,000 in 1897. In other words, the pelagic catch of 1894 exceeded that of 1893 by one hundred per cent, while that of 1897 fell seventy-two per cent below that of 1896. It is not, therefore, strange that the quota of 1897 should show a reduction of thirty per cent as against one of twelve per cent in the breeding herd for the same year.

3. From these data it is plain that the former yield of the hauling grounds of the Pribilof Islands was from three to five times as great as in the years

    This table of statistics need not be quoted here in full. The following section, embracing the ten years prior to 1889 and including 1884, will suffice:

    Year. Datequota
    filled.
    Hauling
    grounds
    driven.
    Numberof
    drives.
    Killedon
    land.
    Killedat
    sea.
    1879 16 71 36 110,411 8,557
    1880 17 78 38 105,718 8,418
    1881 20 99 34 105,063 10,382
    1882 20 86 36 99,812 15,551
    1883 19 81 39 79,509 16,557
    1884 21 101 42 105,434 16,971
    1885 27 106 63 105,024 23,040
    1886 26 117 74 104,521 28,494
    1887 24 101 66 105,760 30,628
    1888 27 102 73 103,304 26,189
    1889 31 110 74 102,617 29,858