F-12 



intemiediate group, but on infrequent occasions and since the IDast Wind Drift has the slowest 

 growing krill of all areas, the mixing would have to be with krill growing more slowly even 

 than these which is clearly impossible. 



Evidence on growth rate by other methods is at present inconclusive. Mackintosh (I967) 

 Mcl^innie (1976) and Clarke (1976) maintained several individual adolescent and adult krill 

 in experimental aquaria and studied growth over several moulte. In all cases growth incre- 

 ment was very small althou^ both authors consider that their experiments were not a true 

 reflection of growth in the natural state. The slow growth rate indicated by these experi- 

 ments may indicate a slow growth rate in the wild. However, more sophistication in experi- 

 mentation will be needed before this approach can be considered as giving a definitive answer 

 to the problem. 



In an analysis of growth curves for a variety of euphausiids Mauohline and Fisher (I969) 

 have calculated average daily growth rates. These are summarised in Table 6.1. 



Table 6.1 Calculated daily growth increment for a variety of euphausiid Crustacea 

 (Mauchline and Fisher I969) 



The fact that the figures for E. superba are muc>i higher than those for any of the other 

 species may indicate that the lifespan used as the base (two years) is too short. A greater 

 lifespan would reduce the daily growtyi increment to nearer the values for the other species. 



