372 DISCOVERY REPORTS 



seasons. Only proof of identity can give value to the rate of reduction and it does not 

 seem possible to obtain this proof indirectly. The failure of the Humpback fishery has 

 been adduced as evidence to show the results of continual attack upon a closed stock, 

 and although some of the data concerning Fins and Blues, especially as regards their 

 movements and the presence of diatom film, appear antagonistic to the general theory 

 of a recurrent population, there is, at any rate, a possibility that this population exists as 

 an entity, and there the matter must be left until marking of whales on a large scale is 

 successfully carried out. 



SUMMARY 



The whale population of the South Georgia area has been investigated in the light 

 of evidence from the corpora lutea and scars on the epidermis. 



The catch has been analysed showing that maxima of physically mature females occur 

 in December, sexually mature not physically mature females in January, and sexually 

 immature females in February. 



Analysis of the age groups of mature whales determined by the corpora lutea over 

 five seasons shows a rate of reduction of 26 per cent and a suggestion that the remaining 

 mature whales, after this percentage is withdrawn, might keep the population at its 

 present level notwithstanding a deficiency in numbers among lactating and resting 

 whales. A shortage of the older age groups is demonstrated, which, should the missing 

 whales be eliminated elsewhere, must lead to an adverse balance. 



On evidence obtained from scars formed in northern waters it has been possible to 

 divide the immature catch into three age groups. 



The importance of definite evidence regarding the recurrence of the same stock in 

 these waters is pointed out and the main features of the lines of research into this 

 problem are put forward. 



LIST OF LITERATURE 



Bennett, A. G., 1920. On the occurrence of Diatoms on the skin of whales. Proc. Roy. Soc. Lond., B, xci, 



P-35 2 - 

 Harmer, S. F., 193 1. Southern Whaling. Proc. Linn. Soc. London. 

 Hinton, M. A. C, 1925. Report on the papers left by the late Major Barrett-Hamilton, relating to the whales 



of South Georgia. Crown agents for the Colonies. London. 

 Hjort, J., Lie, J. and Ruud, J. T., 1932. Norwegian pelagic whaling in the Antarctic. I. Whaling grounds in 



1929-30 and 1930-31. Hvalradets skrifter, Nr. 3. 

 Kemp, S. and Bennett, A. G., 1932. On the distribution and movements of whales on the South Georgia and 



South Shetland whaling grounds. Discovery Reports, vi, pp. 165-90. 

 Mackintosh, N. A. and Wheeler, J. F. G., 1929. Southern Blue and Fin Whales. Discovery Reports, 1, 



PP- 257-54C- 

 Matthews, L. H., 1931. A History of South Georgia. 

 Olsen, 0., 1913. On the External Characters and Biology of Bryde's Whale (Balaenoptera brydei) a new 



Rorqual from the Coast of South Africa. Proc. Zool. Soc. Lond., pp. 1073-90. 

 Risting, S., 1928. Whales and whale foetuses. Statistics of catch and measurement collected from the Norwegian 



Whalers' Association, 1922-5. Rapp. Cons. Expl. Mer., l, pp. 1-122. 

 Risting, S., 1930. Norsk Hvalfangst-tidende. 

 Wheeler, J. F. G., 1930. The age of Fin whales at physical maturity. Discovery Reports, 11, pp. 403-34. 



