THE STOCK OF WHALES AT SOUTH GEORGIA 369 



expected from the north, Fin whales are more often than not moving in a northerly 

 direction (Kemp and Bennett, 1932, p. 181). 



Collective differences between the sexes have also been recognized. Sometimes for 

 a week or more the catch is made up almost entirely of male whales as it was in the 

 early part of January 1926 (Mackintosh and Wheeler, 1929, p. 461) ; sometimes females 

 are predominant; and it has been shown by Risting (1928) that males generally out- 

 number females in the total catches. 



Segregation can be explained on the ground of physical differences between the sexes 

 during the course of a long migration. It is not often possible to say which sex precedes 

 the other on the grounds, but when the large numbers of immature male whales ap- 

 peared in 1926, there was a suggestion, in the later arrival of immature females, that the 

 former might have outstripped the latter in a migration from the same area. 



There are two illuminating features regarding the prevalence of males in the catches. 

 From the statistics of the British Museum (Nat. Hist.) it is recorded that males were 

 slightly in excess of females at the South African stations as well as those of the De- 

 pendencies of the Falkland Islands (Mackintosh and Wheeler, 1929, p. 322). From the 

 same statistics there is evidence that males outnumber females considerably in "Fin" 

 seasons; while in seasons when Fins are scarce, generally, though not invariably, 

 females slightly outnumber males. These indications point to somewhat different areas 

 or methods of concentration of the sexes. The females may concentrate rather farther 

 from the island or in a more diffuse form than the males. Probably also the females are 

 more timid and easily scared by the hunters. In any event there is no reason to suppose 

 that the catch of females is less representative of the ages present than the catch of 

 males, unless deficiency of lactating and resting females is due to some local distri- 

 butional factor at present unsuspected. 



The apparent undue prominence of immatures in the catches applies to males as well 

 as females and to Blues as well as Fins. The fact was commented on by Hinton (1925, 

 p. 162) who, in dealing with the earlier years of the Blue and Fin fishery suggested that 

 from his data, it appeared that the attacks of the catchers were being directed at 

 adolescent Finners and sexually immature Blue whales rather than the adults, since 

 they were easier to kill and certainly easier to handle with tackle designed for the Hump- 

 back. With the change of objective of the fishery came changes in design and power of 

 the catchers and improvements in the tackle, so that Hinton's second reason for the 

 excess of immatures is no longer applicable. There is no doubt, however, that immatures 

 are easier to kill since they are not as easily scared as the older whales. Also they tend 

 to run nearer to the coast and are thus more easily accessible. Both these reasons play 

 their part in increasing the proportion of small whales in the catch. 



In recapitulation let us investigate the catch of Finners taken by the Pesca company 

 during a single season, using all the evidence at our command. In 1929-30 (a "Fin" 

 season) the company captured 750 whales. Fifteen whales were taken before our arrival 

 in South Georgia and nine were missed during the season. Our sample of 726 is there- 

 fore 96-8 per cent of the company's catch. 



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