i6o DISCOVERY REPORTS 



the pairing season and migrate alone to high northern or southern latitudes before re- 

 turning to temperate waters again and joining in the general movement of the schools 

 towards the equator during the winter. 



WHALING AND THE SPERM WHALE 



The Sperm whale forms an important part of the catch only on the Natal, Chile 

 (37-40° S), and Japan whaling grounds (Harmer, 1928); elsewhere the numbers caught 

 are insignificant compared with the numbers of Whalebone whales. The world catch 

 probably does not exceed 2000-2500 Sperm whales a year: it was 2238 for season 1934/5 

 and summer 1935 together. The reason why the whaling industry pays so little attention 

 to the Sperm whale is that Sperm oil is not suitable for the processes of hardening by 

 which the oil from Whalebone whales is converted into edible fat. Further, a very 

 small proportion of Sperm oil contaminates other whale oil and renders it unsuitable 

 for hardening, with the consequence that Sperm oil has to be boiled out and stowed 

 separately. Occasional Sperm whales are, in fact, a decided embarrassment to a whaling 

 station that is engaged in converting a good supply of Whalebone whales. 



The world stock of Sperm whales is thus not seriously drawn upon by the whaling 

 industry, for the number taken annually is at present less than the annual catch in the 

 days of the old American whaling industry of the last century. Harmer (1928) points 

 out that this industry became extinct after the use of petroleum as an illuminant became 

 general, but shows that it started to decline after 1837, more than 20 years before the in- 

 troduction of petroleum, so that the decline could only be due to over-fishing. He adds 

 that the Sperm whale is one of the species about which immediate anxiety need not be 

 felt, though there is no evidence that the immense numbers formerly reported are still 

 to be found. 



The Sperm whale is the species of whale which, owing to its habits, affords the best 

 opportunity for a really scientific and rational regulation of its capture. The species is 

 polygamous, and consequently the capture of bulls only, if not excessive, would in no 

 way damage the stock. Further, a portion of the stock, the older bulls, segregates itself 

 from the schools of cows and immature animals, thus providing proper quarry for the 

 whaling industry and releasing it from the trouble of selecting those whales suitable for 

 capture. The older bulls, being naturally larger in size, are the ones specially suitable 

 for use by the industry. 



It would remain then, to ascertain the approximate latitude that limits the southern or 

 northern migration of the cows and immature whales and to confine the capture of 

 Sperm whales to latitudes higher than those, where practically all are full-grown solitary 

 bulls in good condition. This latitude appears to be in the neighbourhood of 40° N 

 and S. The slaughter of cows in lower latitudes appears to be quite indefensible, for 

 not only may they be pregnant or lactating, but, owing to their small size, their oil yield 

 is low. The demand for Sperm oil is, however, small in comparison with that for the oil 

 of Whalebone whales, so that it is doubtful whether a Sperm whale fishery conducted on 

 rational lines would be of any interest to the whaling industry. 



