WHALEBONE WHALES—MACKINTOSH 257 
Certain changes are worth noting which take place in the compo- 
sition of the Antarctic population in the course of the Antarctic 
summer. As the season advances the proportion of blue whales falls 
while that of fin whales rises. There is a marked decline in the per- 
centage of pregnant females, which become progressively displaced 
or diluted by the arrival of resting and lactating females; and there 
is a slightly higher proportion of old and mature whales in the early 
than in the late summer catches, 
It is to be hoped that means will in time be found of making a rough 
census of the populations of whales, but the problem presents great 
difficulties. Hjort, Jahn, and Ottestad (1933) considered the possi- 
bility of estimating the stock by statistical methods which depend on 
the relations between the size of the stock and progressive changes in 
the number caught in a given area, but realized that such methcds must 
involve assumptions which are at present hardly justified. Whale 
marking might provide information, for the ratio of marked whales 
killed to marked whales at large should be related to the ratio of total 
whales killed to total whales at large, but this method also involves 
incalculable factors. The most direct method would be to count the 
whales seen in a given area, e. g., the strip of ocean viewed from a ship 
during a series of voyages; but whales are seen only in fleeting glimp- 
ses, and the number observed is so much affected by even slight varia- 
tions in atmospheric conditions that a reliable count seems impracti- 
cable. These are problems for the future, and it may be that a com- 
bination of these methods may eventually lead to a rough census when 
the relevant factors are better understood. 
The effect of the whaling industry on the stocks of whales is a large 
subject, and perhaps not quite within the scope of the present article, 
but it has influenced the trend of recent research, and something 
should be said of the location of the industry and of the depletion of 
certain species. Whaling in the Northern Hemisphere has been con- 
fined almost entirely to land stations, and these (of which few have 
been operating in recent years) are placed at points on the coast ac- 
cessible to deep oceanic regions, e. g., the west coast of Ireland, the 
Hebrides, the Californian coast, etc. Many of these localities have 
been referred to above in the section on distribution. In the Southern 
Hemisphere whaling was at first conducted from shore bases, mainly 
at South Georgia, the South Shetland Islands, and parts of the 
African coasts, but after about 1926 the Antarctic pelagic factories 
dominated all other whaling. In the years before the war they 
covered a belt outside the pack ice extending around two-thirds of the 
Southern Ocean from the South Shetland Islands in 60° W., eastward 
as far as the Ross Sea (see fig. 1), but did not penetrate to the Pacific 
sector (60°-180° W.). The International Statistics show that up 
