HORIZONTAL DISTRIBUTION, GROWTH AND DYNAMICS OF DISPERSAL 391 



to the older swarms the resulting graphs in many instances became too attenuated to show clearly 

 where their modal values fell. 



Since the young first year (10-12 month old) spring swarms (p. 370, Fig. 118) as they grow 

 eventually contribute substantially to the mass of the staple feeding-stuff, especially (p. 379) in the 

 second half of November, their developmental condition is also shown in Fig. 133, first year 

 swarms of East Wind origin being distinguished by an asterisk. 



DATE 



STATION 



68 

 64 

 60 

 56 

 52 

 48 

 S 44 

 5 40 



2 3 4 4 5 5 8 10 10 10 10 10 10 10 10 10 13 172022 



3 6 6 8 13 19 19 22 23 24 25 26 26 25 27 27 29 29 29 

 W290W295W298 1831 IB35 1835 1835 1835 1839 1844 1854 I009 1875 1029 2094 2IOO 1039 518 1632 2112 f 25IO | 535 537 548 

 823 624 1825 1835 1835 1835 1835 1835 454 461 1009 1864 494 2093 1624 517 1628 1630 523 757 2139 2513 769 1 25 539 549 



(6)(5) (5)(5) 



a. 36 



I 32 



S 28 



5 24 



-^ 20 



16 



12 



8 



4 



DECEMBER 



4 7 B 8 9 II 12 16 19 19 19 21 21 



(?) (3) (3) (5) 



(4) (4)(5)(4) 



(5) 



10-12 MONTHS OLD SWARMS 



22-24 MONTHS OLD SWARMS 



Scale p<r cent 



(I) (1) ° '°'°° (I) (0 



/2\ O 50 lOO 



) (0 dxo 01 



(I) 



CO 



(00) 



DATE 



STATION 



68 

 64 



60 



56 



52 



46 



uj 

 44 o 



40 I 



36 °= 



32 I 



28 O 



z 



24 UJ 



_l 

 20 



16 



12 



8. 



4 



52 40 32 2: 



580, 102 107 



132 104 lOO 136 171 17 III 108 120 20O 251 564 197 74 I570 65 57 27 99 55 379 79 

 271 103 153 176 49 216 58 37 97 128 64 100 96 62 lOO 37 265 189 42 99 56 7\ 



t SAMPLE FROM SIGHTED SWARM 



Fig. 133. Developmental condition of the staple whale food in spring, the figures in brackets indicating the dominant stage 

 of the female, the figures at the bottom the number of euphausians measured in each 22-24 rnonth old, or, as from Station 

 1029 onwards, each 10-12 month old, sample examined. For vertical scale see legend to Fig. 107. 



The principal features of the developmental condition of the staple class in spring are in brief then 

 as follows: 



(i) In the main this, the principal diet of the whales, is represented in spring by 22-24 nionth old 

 swarms nearing the end of their second year of growth, swarms in which, following Bargmann, the 

 females have reached stages 3, 4 and 5 in October, 4 and 5 in November and 5 and 6 in December.^ 



(2) Broadly these second year swarms fall within a 25-36 mm. length range in the first half of 

 October, a 29-48 mm. length range in the second half of October and first half of November and 

 a 35-56 mm. length range in the second half of November and in December. 



(3) In the second half of spring, from about the middle of November onwards, the 10-12 month 

 old first year swarms, now growing rapidly and developing a strong to dominant, in December some- 

 times an exclusive, over 20 mm. component, contribute more or less heavily to the mass of the staple 

 feeding-stuff. In swarms of East Wind origin, however, as, for instance, in those encountered south- 

 east of Kerguelen (Stations 1630, 1632 and 2139) and at the eastern end of the Bransfield Strait 

 (Stations 537 and 539), this contribution is inclined to be less substantial than it is elsewhere in the 

 northern zone. 



(4) Throughout the season both first and second year swarms display a heterogeneous pattern of 

 modal values. 



(5) Throughout spring the females of the first year swarms are everywhere it seems almost 

 exclusively in stage i. 



1 We have no developmental data for the spring condition of the second year females in the ice-covered East Wind drift. 

 The above, therefore, refers strictly to their condition in the northern or Weddell zone. 



