THE OLDER STAGES i93 



South Georgia but not in the open sea, and if this is so here also perhaps we may have an instance 

 in which a plankton animal of wide adult geographical range is spreading from a restricted spawning 

 area. 



A still higher shelf sea egg frequency than is recorded above (p. 189) is obtained if the Bransfield 

 Strait-Weddell West region be considered by itself, it being there that the majority, 82 in all, of 

 these high latitude shallow water stations were made. Eggs occurred at 41 of them, a frequency of 

 50 "0. But by far the highest frequency we have recorded was encountered during the survey of this 

 region that took place in February 1933 (Discovery Reports, Station List, 1931-3) when eggs were 

 taken at no fewer than 14, or 82%, of the 17 stations that were made. That the frequency should 

 apparently be at a maximum in February is perhaps not surprising, for it is during this month, 

 judging from the particularly large numbers of spent females that have been encountered both then 

 and in March (p. 188, Table 39) that spawning may be said to be at its height. In striking contrast to 

 the pronounced regularity with which eggs were encountered in shelf water in February 1933 it may 

 be noted that out of 129 stations made in the oceanic water of the Weddell drift, the East Wind drift 

 and the South Georgia region in the same month eggs were present at only ten — and this at the 

 supposed peak of the spawning season. 



In view of the pronounced regularity of their occurrence in shelf water it is possible that the eggs 

 recorded in the upper strata there (p. 182, Fig. 19), small or negligible in number though we have 

 found them to be, may represent Eraser's ' scattered product of dispersal ' of much larger masses 

 located below, located perhaps, as the eggs at Station 540 so distinctly suggest, on the bottom itself. 



Not a little of the evidence then, particularly the evidence provided by the near-bottom concentra- 

 tions of eggs and Nauplii recorded at Stations 540 and 2603, suggests that the females find in the 

 cold shelf or slope waters of the continental land, in high or relatively high latitudes, more suitable 

 conditions in which to deposit their eggs than are to be encountered in the warmer oceanic water 

 farther off the coast. It suggests too that spawning in the shelf water of the Bransfield Strait-Weddell 

 West region may be taking place on a bigger scale than elsewhere in the circumpolar sea. In other 

 words, in so far at least as the Atlantic sector is concerned, there would appear to be a distinct 

 possibility that the krill, /ar/rom depositing their eggs anywhere throughout the vast area in which they 

 are known to range, may in fact have a localised spawning place from which the resultant eggs and larvae 

 spread away to populate the whaling grounds through the agencies already described on pp. 99-105. 



Passing to a critical examination of this suggestion it will be convenient first to consider to what 

 extent, if any, it may be said to be upheld by the regional distribution and relative abundance of the 

 spent and gravid females in the circumpolar sea. This, based on the catches of the i-m. diameter 

 stramin nets for the period November, when the first eggs appear, to April, when the last spent 

 females are found, is shown in Figs. 24 and 25. It would appear from these figures that the principal 

 spawning areas are (i) high latitudes in the East Wind drift, (2) the Bransfield Strait, (3) the Weddell 

 drift, notably Weddell West, and (4) the tributary offshoot of that surface stream which reaches the 

 island of South Georgia. It would appear, too, in fact seems clear, that an enormous area of the 

 Antarctic Ocean, the vast extent of the circumpolar West Wind drift, carrying as it transpires neither 

 spent nor gravid females, is not a region where the eggs are laid. 



Although the distribution of these stages does not at first sight point anywhere to any particularly 

 localised spawning ground, except in so far as the narrow coastwise current of the East Wind drift 

 may be said to be localised, the pronounced abundance of spent females that appears in the western 

 part of the Atlantic sector (Fig. 25) suggests strongly that there at least, somewhere in the general 

 area Bransfield Strait-Weddell West-South Georgia, the eggs are shed on a vastly greater scale than 

 they are elsewhere in the circumpolar sea. Narrowing down this region still farther by excluding the 



