CAUSES OF PATCHINESS 



219 



The patches as swarms 

 Since the enormous variation in gatherings of the larger krill revealed by our stramin nets is a measure 

 of the pronounced patchiness that is know^n to exist among the older stages of this species, so it may 

 be said the equally great variation in the larval gatherings of the vertical nets, and in the larval and 

 post-larval gatherings of the stramin nets, reveals a patchiness no less pronounced in the younger 

 stages as well. Hardy and Gunther (1935, p. 211) record the patchiness of very young E. superba 

 (which subsequent analyses have shown to be the Calyptopis and Furcilia stages, but principally the 

 former) revealed by a series of consecutive surface net hauls in the Bransfield Strait in April 1927; 

 while Gunther (1936, p. 173) records a similar tendency to form patches among the very young stages 

 of another euphausian, so far unidentified, encountered near San Juan in the Peru Coastal Current in 

 June 1 93 1. In this locality streaks of a reddish surface discoloration proved to be caused by 'an 

 almost incredible quantity of Euphausian cyrtopias . . . affording a parallel to the swarms of Eiiphausia 

 superba which sometimes colour the Antarctic with patches varying from ochre to brick red '. 



It would appear, in fact, from the enormous variation in catch-figures (Tables 45-7) revealed by 

 the random sampling of our vertical and stramin nets, that E. superba is prone to patchiness 



Table 45. Vertical patchiness. Patchiness in larval E. superba at depths below 250 m., the figures in 



bold type indicating patches supposedly sampled with maximum effect. N2, Second Nauplius; M, Meta- 



nauplius; Ci, First Calyptopis. Stations prefixed by an N or a V are {p. 52) from Norwegian sources 



1500-1000 looo-yso 750-500 500-250 



• ' « , ' , , * , , * , 



Month Station Date N2 M C 1 N 2 M Ci N2 M C 1 N 2 M Ci 



Dec. 762 8 66 — — — — — — — 



Jan. N 42 18 — — 92 



N43 19 _ _ 75 



V 1 1 22 — — 2213 



1492 23 —243- — — — — — 



823 27 327 25 — — 18 2 — — — 



V 12 28 — — 243 



1662 28 5 10 — — — — — — — 



Feb. 1671 2 — — — — 10 I — — — 



V13 12 _ _ g 



1965 15 _ 61 59 — 2 32 — — 58 



N 19 17 — — 19 



618 18 — — — — 20 4 — — — 



620 19 — 46 — 2 10 — — — 



1545 28 _ 138 _ _ 57 78 — — 36 



2594 28 1000* 400* — 434 2240 — — — — — — — 



March 1138 2 — 911 36 — 604 245 — — 485 



2600 3 — — — — 39 1—67 5 — — lis 



1142 4 _34__i8 — — 5 



2603 4 510 94 — 18 387 — — 443 22 — — 20 



"44 S — 8 — — 549 53 — — 51 



636 8 — — — — 171 — — 31 



637 8 — 10 4 — 24 2 — — 36 

 2610 8 — 12 — — 14 2 — — 10 



638 9 — — — — 32 — — 5 

 647 12 — 557 7 — 3702 282 — — 150 



April WS 197 17 _ 115 _____ _ 28 



854 20 _ 137 5 _ 47 7 _ _ 35 



855 20 — 185 36 — 332 67 — — 13 

 2346 27 — 830 10 — 221 41 — — 39 



* Estimated numbers (see p. 89, footnote 3). 



24-2 



