Page:South - the story of Shackleton's last expedition, 1914-1917.djvu/488

366 These captures do not represent the total catch, but are sufficiently reliable to show how the species are affected. The reduction in numbers of the humpback is very noticeable, and even allowing for the possible increase in size of gear for the capture of the larger and more lucrative blue and fin whales, there is sufficient evidence to warrant the fears that the humpback stock is threatened with extinction.

In the immediate northern areas—in the region from latitude 50° S. northward to the equator, which is regarded as next in importance quantitatively to the sub-Antarctic, though nothing like being so productive, the captures are useful for a comparative study in distribution. At Saldanha Bay, Cape Colony, in 1912, 131 whales were captured and the percentages were as follows: 35 per cent. humpback, 13 per cent. fin whale, 4 per cent. blue whale, 46 per cent. sei whale, while nearer the equator, at Port Alexander, the total capture was 322 whales, and the percentages gave 98 per cent. humpback, and only 2 captures each of fin and sei whales. In 1914, at South Africa (chiefly Saldanha Bay and Durban), out of a total of 839 whales 60 per cent. were humpback, 25 per cent. fin whales, and 13 per cent. blue whales. In 1916, out of a total of 853 whales 10 per cent. were humpback, 13 per cent. fin whales, 6 per cent. blue whales, 68 per cent. sperm whales, and 1 per cent. sei whales. In Chilian waters, in 1916, a total of 327 whales gave 31 per cent. humpbacks, 24 per cent. fin whales, 26 per cent. blue whales, 12 per cent. sperm whales, and 5 right whales. There seems then to be a definite interrelation between the two areas. The same species of whales are captured, and the periods of capture alternate with perfect regularity, the fishing season occurring from the end of November to April in the sub-Antarctic and from May to November in the sub-tropics. A few of the companies, however, carry on operations to a limited extent at South Georgia and at the Falkland islands during the southern winter, but the fishing is by no means a profitable undertaking, though proving the presence of whales in this area during the winter months.

The migrations of whales are influenced by two causes:

(1) The distribution of their food-supply; (2) The position of their breeding-grounds.

In the Antarctic, during the summer months, there is present in the sea an abundance of plant and animal life, and whales which feed on