THE STOCK OF WHALES AT SOUTH GEORGIA 365 



mature females may be capable of a natural explanation on the ground of mixed ages 

 rather than on the hypothesis of excessive fishing of a single age group comprising the 

 immature whales. 



If some female whales become mature at two years from birth and some at three the 

 subsequent ages will also vary by one year and the determination of age after maturity 

 by the corpora lutea is involved in this complication. Previously the addition of two 

 years to the number of years from sexual maturity gave the age from birth, but on the 

 new evidence whales pregnant with from one to four corpora lutea may be either two 

 or three years old, those lactating with the same number of corpora lutea either three or 

 four years old, instead of two and three years from birth respectively. Similarly with the 

 later groups in the form of a double series. The rate of reduction is unaffected, but it 

 treats two years as one, in that pregnant whales may be actually of the same age from 

 birth as lactating whales and lactating whales as pregnant whales if they differ in series. 

 Physiologically the age is the same, as also is the actual age starting from sexual maturity. 

 The rate of reduction then is artificial in that its starting point is physiological and it 

 does not take into account the years preceding sexual maturity. 



The uniformity of the curve of reduction is the most striking argument in its favour, 

 but it applies only to mature whales. The immatures cannot be added to the graph of 

 reduction nor can the figures be considered with those of the mature whales. The reasons 

 are not far to seek. There are 126 mature whales whose age is not known, which, because 

 they formed part of the catch, should be included in the figures, as against only four 

 whales believed to be immature on account of their length ; also there is uncertainty in 

 the number of ages represented by the 281 immatures as has just been deduced from 

 the evidence of the scars. 



Considered broadly our figures suggest a population unduly weighted with im- 

 matures and with pregnant whales, and we have now reached the point when general 

 consideration of the catch and stock becomes all important : How far does the season's 

 catch represent the stock and what evidence have we concerning the recurrence of the 

 same stock at South Georgia? 



Considerable changes have taken place in the South Georgia fishery during the 

 twenty-seven years of its existence. Until 1907 the company founded by Larsen worked 

 alone and made large catches of Humpbacks and Southern Right whales. Matthews 

 (1931) says — " He (Larsen) arrived at Grytviken in December, 1904, and at once started 

 work. Whales were plentiful and undisturbed, for months his catcher did not leave 

 Cumberland Bay, as she was able to get all the whales that could be dealt with close 

 inshore". These were the conditions that attracted other ventures in 1907, '08 and '09, 

 with the result that in 1909-10 seventeen catchers were operating from a series of stations 

 on the north side of the island forming a base line to the fishery roughly eighty miles in 

 length. There were no restrictions. All species were taken when opportunity occurred, 

 but few Sperms and Sei whales appeared in the catches and these species played no part 

 in the later development of the industry. It is said that Right whales were abundant at 

 the beginning of the fishery, but their number since that time has been small. 



