z66 DISCOVERY REPORTS 



large numbers of S. gazellae. These are nets which have been towed at many stations at a depth of 



less than 5 m. below the surface. 



Fig. 20 shows the size and numbers of individuals taken in the 1 m. oblique nets at Station 461 

 (56°44' S. o° 23' W, 21.X.30), a 24-hour station in Antarctic water, and it demonstrates that size 

 increases with depth. The animals have been plotted on Fig. 20 by their length in mm. against the 



% OF TOTAL 

 20 JO 



IOOO 



I500 J 



300 



4 OO 



500 



z 6OO 



I 



Q- 



UJ 



a 700 



. .jt,'.v-MSj t at 

 ■ vvtf • » • 



• •• •/ 



• • • tc 



>. 



/•• 



90 



Fig. 19 



10 20 30 iO 50 60 70 8C 



TOTAL LENGTH MM 



Fig. 20 

 Fig. 19. The vertical distribution of S. gazellae at 129 vertical stations: the numbers at each depth are represented as a 

 percentage of the total for all depths. 

 Fig. 20. The vertical distribution of S. gazellae at Station 461 showing the increase in size with depth. 



mean depth of each haul, e.g. the mean depth for a haul from 280 to 180 m. has been assumed to be 

 230 m. The scatter of the observations when plotted is considerable but, although there are a number 

 of animals of the smaller size groups present in the deeper hauls, it must be noted that these were 

 made with flights of oblique nets, and therefore the paying out of the nets must be halted from time to 

 time for attachment of more nets; thus the deeper ones may have sampled shallow layers for short 

 periods of time. As the small animals are present in the upper layers in large numbers, it is likely that 

 many of the small animals in the deep hauls are due to this source of error. 



