DISCUSSION OF RESULTS 187 



the Strait, passing outside the South Shetland Islands. Towards the close of the season a 

 concentration at the southern end of Bransfield Strait is the general rule, the whales 

 presumably passing up through it on their northward migration. Sometimes, however, 

 this concentration was absent. As already noted it was not found in 1923-4, when both 

 Fin and Blue whales appear to have gone directly towards the north, and in the following 

 season a considerable proportion of Fin whales seem also to have avoided the strait. 



The south-western limits of the whaling grounds extend to the Biscoe Archipelago, 

 but this locality was only reached by the whalers in seasons 1923-4 and 1925-6. It is to 

 be presumed that in both these seasons the pack-ice in the Bellingshausen Sea lay 

 unusually far to the south. Season 1929-30 was an exceptionally open one in the Weddell 

 Sea. The vessels of the Weddell Sea fleet reached very high latitudes and those of the 

 South Shetland fleet — for the only time during the period under review — were able to 

 work east and south-east of Joinville Island. This is shown for Fin whales in Plate 

 XXXII. Blue whale returns for this season are so few that monthly charts cannot use- 

 fully be given, but the data are included in the totals shown in Plate XL in order that the 

 distribution of the two species can be compared. 



Whales do not appear to occur in such dense concentrations in the South Shetlands as 

 in South Georgia. During the eight seasons reviewed the greatest concentration — as 

 shown by the number taken by the whalers — was of Fin whales in Bransfield Strait in 

 April 1927. In an area of 828 sq. miles 229 whales were killed during this month, or 

 277 whales per 100 sq. miles. This is less than one-third the maximum density found 

 on the South Georgia grounds (see p. 180), but the two figures are not strictly com- 

 parable. 



The directional data from the South Shetlands have been summarized in the same 

 way as those from South Georgia and the results are shown in Figs. 5 and 6. They are, 

 if anything, less consistent than the South Georgia results, and their validity, as already 

 explained, is open to question. In Table XI the numbers of components along the four 

 cardinal points are given, and since a reverse movement is to be anticipated in the latter 

 half of the season, the numbers for each species are grouped in two series— the first series 

 running from November to January and the second from February to April or May. 



It cannot be said that these data give any clear support to the theory that whales 

 normally travel south-west in the first part of the season and north-east in the latter 

 part. Such a resuh is, however, to be found in the Blue whale records for 1924-5 and 

 1925-6 and with less certainty in the Fin whale records for 1922-3 and 1924-5 (see 

 Figs. 5, 6). In all other seasons no agreement with this theory is to be found. 



Table XI shows that in these data the predominant component throughout the season 

 is the westerly, the only exception being in Fin whales, where in the latter half of the 

 season the northerly component is in slight excess. If, however, the first half of the 

 season is compared with the second it will be seen that in the latter the numbers of 

 southerly and westerly components have diminished and the northerly and easterly have 

 increased. Only in this respect do the figures bear out the theoretical movement inferred 

 from the positional data. 



