HORIZONTAL DISTRIBUTION, GROWTH AND DYNAMICS OF DISPERSAL 409 



Comparable gatherings, however, cannot be obtained in the East Wind drift, the ice conditions in 

 these high latitudes confining effective sampling to a short period lasting only from January to April, 

 when the larvae (p. 361), having scarcely (even in April) outgrown their First Calyptopis state, escape 

 through the meshes of the stramin net and the early adolescents are non-existent.^ Clearly, then, as 

 illustrated here, the relative abundance of the total surface population in the East Wind zone is an 

 under-portrayal of the facts (i) because it does not include the First Calyptopes, known to be plentiful 

 there (p. 310, Fig. 74 and p. 311, Fig. 75) from February to April, and (2) because further sampling 

 of the total population in this coastal belt is prevented by pack-ice from May until the end of the 

 year. 



I have alluded repeatedly to the major problem that confronts us in the East Wind zone, and indeed 

 this vast region, about which we know so little, may for long, if not always, present a stumbling-block 

 to Antarctic oceanographers. Even if our existing vessels could penetrate it freely, at the right seasons 

 of the year, to discover what is going on, they would still be confronted with conditions, extreme cold, 

 prevailing darkness and a frozen sea, such as no ordinary research ship has yet had to combat; and 

 the problem of launching a workable oceanographical programme, from the mechanical standpoint 

 alone, would be enormous. Some day perhaps we shall have the right ships^ and the right gear to 

 tackle these conditions. Meanwhile, having regard to the rich harvest gathered by the summer whale 

 fishery from these coastal waters, I would say that the autumnal, winter and spring population of the 

 krill in the East Wind zone, in one developmental phase if not in another, will prove to be just as rich 

 as, if not richer than (see PI. Ill), the massive accumulations of this species we record, at all times 

 of the year, from the more readily accessible waters of the Weddell stream. 



Other major features of the gross distribution of this species, now sharply defined by this mass 

 presentation of the results, are (i) its absence from, or pronounced scarcity in, the West Wind drift, 

 except where it is affected locally by East Wind influence, (2) its pronounced scarcity up to very high 

 latitudes in the Pacific sector where the former international whale sanctuary used to be, at least 

 between about 100° and 160° W, (3) its absence from the shelf region at the head of the Ross Sea, 

 (4) its great scarcity in the supposed backwater that in the Atlantic sector seems to separate the east- 

 flowing (Weddell) from the west-flowing (East Wind) stream, and (5) and lastly the abolute limits of 

 its geographical range. 



It is interesting to record that, following the reopening of the Pacific sector to whaling in 1956, 

 Japanese expeditions to this region have reported (Nemoto and Nasu, 1958) a number of instances 

 where fin and humpback whales, apparently finding krill hard to get, were not only substantially 

 augmenting their normal diet with Thysanoessa macrura but on occasion feeding exclusively on 

 this species. This important Japanese discovery might well it seems be linked up with our own 

 results, for it must be significant that the occurrences of T. macrura in the stomachs of these 

 Pacific whales were confined almost exclusively to the area between 100° and 130° W, to the very 

 region in fact where our net hauls (Fig. 143 and p. 394, Fig. 135) show the larger species to be so 

 scarce. 



1 It is true (p. 355, Fig. 107; p. 379, Fig. 124) that swarms of very small whale food are plentiful in the East-Wind 

 zone throughout the summer, but these could hardly be called early adolescent, since they represent the retarded 

 product of the hatchings of a year or more before. 



^ The hovercraft, for instance, springs readily to mind. It would I believe be able to settle gently and safely on the polar 

 pack, and above all would skim swiftly over its flat surface between stations, except perhaps in places where the ice is subjected 

 to severe pressure and rafting such as for instance we find in the Weddell Sea. 



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