THE OLDER STAGES 165 



possible speed to their required level. Even so it will be seen such measures as were taken were not 

 enough to prevent some sampling by the deeper level nets of both young and old swarms at the 

 surface as soon as full darkness set in. 



Table 33. Measurements of the krill in the 10 and 22 month old swarms sampled by the subsurface 

 closing nets at Station 1835, older swarms in roman type, younger swarms in italics 

 Series ... (a) (b) 



State of light 

 Depth (m.) 



Length range in 

 2-mm. groups 



No. measured 

 Total sample 

 No. measured 

 Total sample 



10 

 12 



14 

 16 

 18 

 20 

 22 

 24 

 26 

 28 



30 

 32 

 34 

 36 



38 

 40 

 42 



44 

 46 

 48 



50 

 52 

 54 

 56 



Broad daylight 



Sun- 

 set 



Dusk 



Full darkness 



250 210 180 164 150 128 84 77 40 30 20 ID 



20 



40 46 66 128 



2 



5 

 10 



34 

 84 

 91 

 19 



2 



3 

 4 

 2 



2 



1 

 3 

 5 

 4 

 5 

 3 

 1 



2 

 6 

 9 

 3 



1 



1 

 1 

 6 



19 



30 



4 



4 



12 



26 



23 



25 



9 



I 



2 



I 



I 



I 

 I 



3 



4 



8 



10 



23 



16 



10 



6 



4 

 I 

 I 



I 



9 



13 



20 



21 



21 



16 



16 



12 



8 



3 



4 



16 



36 



23 

 21 



4 

 2 

 I 

 3 

 3 



4 247 



4 g8o 



— 104 



11 

 11 



24 21 61 



24 21 61 



144 109 23 



2 

 6 



8 

 6 



7 

 8 



3 

 3 

 3 



834 706 144 109 23 



1 

 1 



46 

 46 



The numbers and measurements of the krill taken in both surface and subsurface nets at this station 

 are given in Tables 33 and 34, which show that the young 10 month old swarms at least seem to be 

 concentrated permanently in the surface (0-5 m.)^ stratum whatever the condition of the light. It 

 will be seen, however, that the gatherings obtained late on in dusk and in full darkness are con- 

 spicuously larger than those obtained under conditions of stronger illumination, and this no doubt 

 is due to the measure of avoiding action the krill, even at this early stage of their development (p. 262), 

 can take of the daytime surface nets. It will be seen too that while the young swarms were virtually 

 absent from the daylight, sunset and dusk subsurface hauls (Table 33, series {a)) very small samples 

 of them were apparently taken at 20 m. and deeper after full darkness had set in. This, however, might 



1 The large catch that purports to have been taken at 10 m. in full darkness (Table 33, series {b)) also probably came from 

 the 0-5 m. level, the net, owing to a miscalculation in shooting, having fished on or very near the surface for some minutes 

 before the warp could be adjusted to its proper angle. 



