THE DEVELOPMENT AND LIFE-HISTORY OF KRILL 127 



not therefore be approaching maturity, that is at stage 5, until the succeeding September, nor will 

 they be fully mature before the January (or April) after that. The overlap of the stages in the three 

 batches of eggs and the resulting mixed composition of the euphausian population is clearly shown. 

 The picture could be made even more complex, if the batches of eggs from every month in the whole 

 spawning season were represented, but I decided not to attempt this, because the diagram would lose 



in clarity. 



(2) Grozvth of the etiphmisian population as a whole. By the second method mentioned on p. 120, 

 the population was sexed, measured and divided into adolescents and adults, males and females again 

 being treated separately. The average monthly lengths of adolescents and adults were then calculated 

 (Table i8). 



Table i8. Showing average length per month of larval, adolescent a?id adult Euphausia superba 



Month 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



May 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



May 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



Average length per month of 



larvae and adolescents compiled 



from Fraser's paper 



Larvae 



Av. 



length 



mm. 



I 

 I 

 4 

 4 

 S 

 6 

 8 

 10 



10 

 II 

 13 

 13 

 16 



No. of 

 speci- 



Adolescents 



Av. 



length 



mm. 



5 



5 



56 



lOI 



182 



177 



18 



3 



29 

 27 

 33 

 49 



No. of 

 speci- 



Average length per month of 

 adolescent and adult males 



Adolescents 



Total 



13 

 14 

 15 

 18 

 20 



23 

 24 



Av. 



length 



mm. 



No. of 

 speci- 

 mens 



686 



14 

 12 



33 



54 



4 



5 



2 



13 

 14 

 19 

 23 

 26 



29 

 36 



38 



39 



33 



39 

 40 



34 

 34 



Adults 



Av. 



length 



mm. 



No. of 

 speci- 

 mens 



Average length per month of 

 adolescent and adult females 



Adolescents 



Av. 



length 



124 



19 



19 



356 



316 



437 

 304 

 778 



330 



368 



40 



39 



4 



146 



41 



3197 



44 

 47 

 44 

 45 

 51 

 51 

 52 

 52 

 SI 



12 

 44 



147 

 39 



176 



133 

 164 



19 



15 



13 

 18 

 18 

 21 

 23 



25 



31 



35 

 34 

 31 

 39 

 35 

 32 

 27 



No. of 

 speci- 

 mens 



Adults 



Av. 

 length 



No. of 

 speci- 



Month 



749' 



28 



30 

 356 

 293 

 351 

 252 

 660 



415 



309 



62 



93 



II 



176 



21 



3057 



40 

 42 

 41 

 41 

 45 

 48 



51 

 50 

 47 



36 



34 

 200 



96 

 182 

 142 

 221 



150 

 212 



1273 



I adult in July neglected. 



Larvae = nauplius to 6th furcilia. 



Adolescent males = stages 1-5 ( + Fraser's adolescents). 



Adolescent females = stages 1-3 ( + Fraser's adolescents). 



Adult males = stages 6-7. 



Adult females = stages 4-7. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



May 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



May 



June 



July 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Jan. 



Feb. 



Mar. 



Apr. 



Total 



