PHOSPHATE, PLANKTON AND WHALE DISTRIBUTIONS 297 



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FIN WHALES BLUE WHALES 



Fig. 163. Whale distribution at South Shetlands in February 1929 (from Kemp and Bennett, 1932). 



To test the hypothesis of animal exclusion or the opposite interpretation further a 

 deduction was made in the other direction. In February-March 1928 the 'William 

 Scoresby ' took a number of phytoplankton samples off the north-east and south-east 

 coasts of South Georgia, but no phosphate observations. The whales had the distribu- 

 tion shown in Fig. 164, a distribution which is almost the opposite of that seen in our 

 1926-7 survey (Fig. 141). From this, if the animal exclusion or the opposite hypothesis 

 is correct, one would deduce that the phytoplankton conditions were the reverse of those 

 in 1926-7 (Fig. 38), and that there would be a zone of dense phytoplankton stretching 

 along the north-east side of the island. It is unfortunate that phytoplankton samples were 

 not taken on the western side of the island. Only some of the samples had been analysed, 

 but Dr Kemp kindly had all their volumes measured and sent me the results, which are 

 plotted in Fig. 165, using the same contour scale as was used in the volume chart of the 

 1926-7 survey. A dense belt of phytoplankton is seen round the eastern side of the 

 island a little way from the coast. Dr Mackintosh has kindly provided me with figures 

 of the Euphausia superba distribution for this survey; these I have plotted in Fig. 166 

 putting in in addition the outlines of the phytoplankton contours from Fig. 165. We 

 see again that the Euphausians are not in the region of dense phytoplankton, but are 

 found in the belt of medium phytoplankton separating the dense from the poor phyto- 

 plankton. The February whaling concentration was quite to the west of the southern 

 line of stations, so that the Euphausians in this position were not sampled, but its posi- 

 tion lies in the probable path of the continuation of the medium phytoplankton zone, 

 so that a concentration of Euphausians might be expected there. Actually the southern 

 line was taken in early March (the dates of the lines of stations are given in the charts), 

 and from Fig. 167 we see that in March the whale concentration had broken up and 

 comparatively few whales were taken. Some of the Fin whales in March still extended 

 to the west of the island, but it is also seen that a small number were moving up the 

 east coast along the belt of Euphausians inside the dense phytoplankton zone. 



