2o8 DISCOVERY REPORTS 



spawned eggs and larvae, where development is slow, but small for fast-developing eggs such as, for 

 instance (Ahlstrom, 1943), pilchard. In the high latitudes where the krill are spawning, in so far at 

 least as temperature goes, winter is virtually perennial, and so all in all it seems the southern stage 

 might be well set for a wide margin of drift between captures of Nauplii or Metanauplii and the 

 spawnings from which they spring. 



Although over the great expanse of shallow soundings at the head of the Ross Sea (p. 125, Fig. 

 13) an immense body of intensely cold, highly saline water must be formed in winter, just as in 

 the Weddell Sea, it is unlikely as Deacon (1937, p. 115) has said that it can escape to the north to 

 flow away as a bottom current because of a ridge (Pennell Bank) extending across the northern 

 entrance to the gulf. Herdman (1948 a), however, has shown that close to the Victoria Land coast 

 there is probably a gap in the ridge through which the cold water it seems might in fact escape, 

 although if any does so, as Fleming (1952) suggests, its effect is likely to be small. Our repeated 

 failure to strike the Nauplii and Metanauplii in the deep oceanic water to the north of the Ross embay- 

 ment during the spawning time, particularly in January, February and March, may well, therefore, 

 be associated with the absence of any major outflow of bottom water in this locality. 



Deep spawning reconsidered 



Although our observations point to a preponderance of spent and gravid females at the surface 

 (p. 188, Table 39) and to their virtual absence far below^ we cannot altogether disregard the possibility 

 that in oceanic water the gravid females may sometimes sink or swim down to great depths in order 

 to lay their eggs. For if this be ignored it is difficuh, if not impossible, to explain, in terms of deep 

 transport in the bottom water from a distant locus of spawning in Weddell West, the substantial 

 occurrences of Nauplii and Metanauplii we record in Weddell East (p. 90, Table 13) at Stations 2594 

 and 2346 in February and April. The difficulty is obvious, for Station 2594 in 00° 1 17' E lies approxi- 

 mately 1500 miles, and Station 2346 in 19° E approximately 2000 miles, east of the Graham Land 

 coast, and if deep transport of eggs from this distant locality was in fact responsible for the presence 

 of the Nauplii and Metanauplii at, for instance. Station 2594, it would have to be assumed— supposmg 

 the larvae to have had their origin in a far western spawning that took place in mid-season, say about 

 the middle of February— that since Station 2594 fell on the last day of that month, the bottom water 

 was travelling at about 4 knots, approximately 100 miles a day, which while possible (pp. 212-15) is 

 difficuh to believe. It is even more difficult to explain, in terms of deep transport, the occurrence still 

 farther east of the Metanauplii at Station 2346, for in this instance, again supposing a mid-season 

 spawning, it would have to be assumed that, since this station fell on 27 April, the bottom water had 

 been carrying eggs that did not hatch, or if they did hatch, without the resultant larvae rising, for 

 a period of close upon 2 months if not more. This again seems hardly credible. In short, these oc- 

 currences of deep larvae so far from Weddell West could only be explained in terms of deep transport 

 if the bottom current were travelling at some phenomenal speed or again if the life span of the 

 developing eggs, Nauplii and Metanauplii were spread over an incredibly long period and the de- 

 velopmental ascent took equally as long. In so far, however, as the deep larvae in 0° are concerned 

 there might it seems be other suitable shelf or slope regions, as for instance off the Princess Martha- 

 Coats Land coast (p. 58, Fig. 4), over which the krill might be spawning and away from which the 

 cold water might be sinking, localities from which it might well be that the eggs and developing 

 Nauplii could be carried as far east as Station 2594, if not in fact beyond, without assuming an 

 unduly fast rate of travel or an abnormally long lapse of time. In regard to this suggestion it may 



1 The net result of well over 1000 oblique and vertical hauls made below 500 m. during the breeding season (Tables 38 and 

 39) was the capture of 14 adult females of which four were gravid and one spent. 



