THE SEI WHALE 



269 



This well marked unimodal graph confined to these months, at first sight appears 

 to indicate that there is a very definite migration of Sei whales into South Georgian 

 waters in the early months of the year. But such a conclusion must be drawn with 

 caution. Admittedly, the peak in the graph shows the presence of Sei whales on these 

 grounds, but the converse is not necessarily true: it means that Sei whales were not 

 captured but not necessarily that they were not there. 



The whaling season at South Georgia usually opens with a wave of Blue whales 

 passing southwards, succeeded by a wave of Fin whales following at about a month's 

 interval. Early in the new year in many seasons the main body of the Fin whales has 

 passed on and there is consequently a relative scarcity of these larger species on the 

 whaling grounds. It is then that the whalers turn their attention to the Sei whales, which 

 are much too small to be of any interest to them while there are plenty of the larger 



Jan ' Feb Mdr Apr Mavj 



Fig. 105. Sei wiiale. Monthly catches at South Georgia, 1927-31. 



species available. Consequently the peak in the graph may indicate the absence of 

 Fin and Blue whales rather than the great influx of Sei whales. 



Nevertheless Sei whales, like the Fin and Blue whales, undoubtedly pursue a south- 

 ward feeding migration during the southern summer and a northward one to warmer 

 waters for breeding in the winter ; but if more extensive figures were available it is 

 possible that the graph of their occurrence would not have so sharp and well marked 

 a peak as has that derived from the figures of the whaling catch. 



The Sei whale scarcely appears at all in the whaling returns from places farther south, 

 so that the unimodal graph of its occurrence at South Georgia is probably a correct 

 indication of the approximate latitude in which the return towards the north occurs. 

 It may be mentioned also that the whalers believe that with the arrival of the Sei whales 

 the best part of the season for Blue and Fin whales is over ; but as pointed out above. 



