370 DISCOVERY REPORTS 



escape periodic destruction by ice ; their continued existence on these sites would appear 

 to depend largely on their capacity to re-establish themselves from deeper water after 

 the ice had cleared away. 



The apparent absence of kelp from these islands is perhaps due to the low tempera- 

 tures of the water characteristic of this and other similar localities from which it is known 

 to be absent. According to information kindly supplied by Mr G. E. R. Deacon the 

 surface temperature at South Georgia (where kelp is so abundant), even in the open 

 sea, does not fall below — 1° C. for more than three months in any normal year, while 

 close inshore it may reach a maximum of 3-6° C. in January to February. At the 

 South Orkneys, owing to the influence of the Weddell drift, considerably colder 

 conditions prevail, though in summer they may be subject to some variation according 

 to the presence or absence of pack-ice in the surrounding seas. Deacon^ shows the 

 -i°C. surface isotherm in November-December 193 1 as passing well to the north 

 of the group. Even in February, the warmest month, if there is much ice about, 

 very low temperatures are possible. Between February 14 and 17, 193 1, the surface 

 temperature in Sandefjord Bay varied between —0-5° and — 1*5° C, the average being 

 about —1-0° C. Moreover even when the islands are ice-free the surface temperatures 

 never seem to rise very far above zero. Throughout January 1933, a month marked 

 by the complete absence of pack-ice and by more than the ordinary amount of 

 sunshine, the surface temperature all round the group rarely rose above i°C., and 

 for the greater part of the period it was either below or about 0-5° C. 



SEALS 

 With the exception of the sea lion, whose habitat is in a warmer climate, all the known 

 species of southern seals, the elephant, leopard, Weddell, Ross and fur seals have from 

 time to time been recorded at the South Orkneys ; and all except the last, which is now 

 thought to be extinct in the more southerly dependencies of the Falkland Islands, are 

 known to inhabit or visit the group at the present time. 



The Fur Seal (Arctocephalus australis, Zimm.) 

 Although the fur seal that once crowded the South Shetland beaches were all but 

 exterminated between 1820 and 1822,^ the scattered survivors being afterwards left in 

 comparative peace were able to multiply afresh and the stock increased to an extent 

 that gave fair promise of complete recovery. Fifty years after the initial slaughter an- 

 other generation of sealers visited the South Shetlands, and so far had the seal re- 

 established themselves that between the season 1871-2 and 1891 at least 18,000 fur 

 sealskins were taken from various parts of the group .^ From this second catastrophe they 



1 Deacon, G. E. R., 1933, A General Account of the Hydrology of the South Atlantic Ocean, Discovery 

 Reports, vii, p. 183, fig. 8. 



2 Weddell {loc. cit., supra, p. 141) estimates that during the years 1821 and 1822 320,000 were killed. 



3 See Jordan, D. S., 1899, The Fur Seals of the Pribilof Islands, part ill, p. 314 (Washington) ; also Matthews, 

 L. H., 1931, loc. cit., supra, p. 83. 



