jg5 DISCOVERY REPORTS 



(2) that they might be liberated deep down in oceanic water (Station 2594) far away from land. At all 

 three stations, however, the possibility that they might have sunk to their locus of deep concentration 

 from a considerably higher level must always be kept in mind. 



Although little satisfactory information about the depth of spawning can be gathered from the 

 vertical distribution of the eggs themselves, the vertical distribution of the breeding adults— the 

 pairing sexes and the spent and gravid females— points to it being a surface rather than a deep 

 phenomenon. The complete record of the adult males and females taken in the vertical nets since 

 these investigations began, based on the analyses of over 3000 samples from the East Wind-Weddell 

 zone, is shown in Table 38. It is a meagre record for all depths, revealing the deep occurrence of 

 adults, which Eraser (p. 179) originally supposed might be connected with deep spawning, as a 

 phenomenon of exceptional rarity, to which, as the negligible deep catches of spent and gravid females 

 bear further witness, we cannot it seems attach very much significance. A single net, however, out of 

 this enormous series of virtually negative hauls, the 250-100 m. net at Station 356, in which 39 gravid 

 and three spent females were taken, does it seems provide some evidence that spawning, although not 

 necessarily a very deep operation, might take place some little distance below the surface. Clearly this 

 net must have struck an isolated subsurface pocket of adult females, producing by horizontal standards 

 a small, but by vertical standards a distinctly large, sample which, again (p. 160) having regard to the 

 low sampling power of the vertical net and the distinct possibility (p. 149) that the pocket itself might 

 have been one of shallow draught, might in fact have represented a subsurface congregating of 

 spawners in some unknown, but perhaps not inconsiderable measure of abundance. Since, however. 

 Station 356 was made on the South Georgia whaling grounds, a region it will be shown presently 

 (p. 190) where virtually no spawning takes place whatsoever, the occurrence of gravid females a short 

 distance below the surface there, in so far at least as the major aspects of the egg-laying are concerned, 

 seems of doubtful significance. 



Perhaps not too much weight can be attached to the evidence from the vertical nets, because the 

 scarcity of any of the larger forms, even near the surface, shows their low catching capacity. The 

 larger towed nets, however, give more significant results. The vertical distribution of the adult males 

 and females based on the much more voluminous data from our towed stramin nets is shown in 

 Table 39, the figures being derived in a large measure from the published records of Bargmann^ 

 (1945, Appendbf), but including much additional information gathered from the field observations 

 of other members of the Discovery staff. In this table, which is based exclusively on our obser- 

 vations in the principal region of euphausian abundance (the East Wind-Weddell system) the figures 

 for the surface (loo-o m.) layer show the average monthly catch, that is, the total monthly catch 

 divided by the total monthly net hauls, the figures for all levels below 100 m. showing the total 

 monthly catch, not the average, since the latter it will be seen proves to be so small that in the vast 

 majority of instances it can only be expressed as a very small fraction. Furthermore, owing to their 

 extreme smallness, the catches of adults in the large 2-m. diameter TYE nets so extensively used 

 below 250 m. have not been expressed in terms of standard i-m. diameter stramin net catches as 

 described on p. 157. Such subsurface catches of adults as were recorded in the larger nets were in 

 fact so small that they have been entered in Table 39 as they stood, regardless that is of the size of the 

 apparatus used or of the period of towing involved. In order, however, to give full expression to their 

 smallness, in every instance where the large net was used it has been regarded as having represented 

 four hauls of the smaller net, when fished for 30 min., or as having represented t^/T hauls of the 

 smaller net, if fished for longer, where again (p. 157) t is the actual time of fishing of the TYE, and 

 T the standard time of fishing of the i-m. diameter stramin net. 



1 Corrected to conform with the total catches of the nets from which her samples were derived. 



