522 EXTINCT AND VANISHING MAMMALS 



localities where whaling was carried on in the Antarctic. In 

 1923 Captain C. A. Larsen commenced operations on a larger 

 scale with a floating "factory," accompanied by five "whale- 

 catchers, " and he extended his field into the Ross Sea. Mean- 

 while, from 1910 on, the cool waters about South Africa were 

 being intensively searched for blue whales and other species. 

 Laurie (1937, p. 270) has presented in tabular form the annual 

 catches made in the Antarctic and South African seas, respec- 

 tively, from 1904-5 to 1935-36. At the latter localities the 

 catch is taken in the southern winter, and soon after 1913 it 

 rose to large figures up to over 300 annually; in 1922-23 it was 

 1,074; and in the years 1925-26 and 1926-27 attained a maxi- 

 mum of over 1,700 (1,744, 1,743, respectively). Thereafter 

 began a rapid decline to as few as 71 in 1933-34, the last year 

 for which statistics were available. 



In the past 15 years the numbers killed in the Antarctic 

 seas have risen to an appalling total. Between the years 

 1927-28 and 1935-36 the number annually taken fell but once 

 below 12,000 and in one year (1930-31) reached the peak 

 figure of 29,410! It is pointed out by Laurie and others that 

 the high percentage of immature whales taken on the African 

 coasts makes "this fishery proportionately more destructive 

 than the more southerly fisheries, " in which a larger proportion 

 consists of adults. 



Studies of the whales caught, as carried on by the Discovery 

 Investigations, demonstrate that the female blue whale be- 

 comes sexually mature when a length of about 78 feet is at- 

 tained. At birth the young one is approximately 23 feet long, 

 and attains breeding size at the age of about two years. The 

 period of gestation is approximately a little over ten months. 

 The whales continue to grow slowly for about ten years. 

 Breeding takes place probably once in three years or "once 

 every two years at best, " as shown by the study of ovaries and 

 the count of corpora lutea in those killed. It is obvious that 

 this rate of increase is rather slow but is offset by the proba- 

 bility that under usual conditions a blue whale should live to 

 be at least 30 years old. 



As to the prospect for the future, it seems clear that the 

 northern stocks of the blue whale are much depleted and that 

 although the southern stock was perhaps originally the more 

 abundant, it too has in recent years declined rapidly. This is 



