GROWTH AS INDIVIDUALS AND SWARMS 255 



Although the East Wind drift is virtually closed to vessels except from January to May there are 



enough data from this short period to show that, following the late spawning and subsequent slow 



larval growth-rate in these high latitudes, the mode values of both second and third year swarms, 



at their maxima and minima, tend to fall persistently below the corresponding values for the northern 



DEPTH 



FURC 6 



. 5 



. 4 



3 



2 



I 



CAL 3 



2 



• I 



META 



NAUP 2 



N9 EXAM- 

 -INED 



8 

 762 



JAN 



28 28 



FEBRUARY 



2 4 17 17 17 17 282B28282825 



MARCH 



APRIL 



2020202020202021 22 22 23 



3333244444488889 22 22 22 2026 25 

 1662 1671 N19 NI9 1545 1545 1545 2600 260O 355 2603 2603 2603 26IO 2610 1713 1713 I720 854 854 855 855 2335 1346 

 Vi2 VH NI9 VI4 1545 1545 361 2(00 2600 2503 2603 2603 358 26IO 359 1713 374 2300 854WI99 855 W20O2335 



TiMffcWft^cfUVW 



D 



DEPTH 

 250-0 



5OO-250 



1000 -500 



REGION 



^ WD 



1 JL 13 T ^ ^ W ° ''°'°° _lT 1 T 



15 II 19 39 138 35 19 40 115 617 387 20 39 



22 59 512 134 116 328 72 167 SOI 445 52 SO 



10 97 90 17 142 108 221 98 15 84 

 16 44 119 48 287 35 45 13 154 45 



5 FURC 



5 



4 



3 



2 



I 



3 CAL 



2 



I 



META 

 2 NAUP 



N5 EXAM- 

 -INED 



•*■ SAMPLE FROM 1500 - lOOO 



Fig. 56. Developmental condition of larval swarms in the East Wind drift, showing the corresponding condition of 

 the oldest larval swarms found in the Weddell drift at the same, or approximately the same, time. 



68 

 u) 64 

 => 60 

 g 56 

 " 52 

 2 48 



1 44 

 40 



S 36 

 ixJ 32 

 i 28 



2 24 

 20 



f 16 

 i ' = 



N? MEAS- 

 -URED 



NOV 



DECEMBER 



JANUARY 



FEBRUARY 



MARCH 



APRIL 

 MAY 



2 2 28 29 3 7 8 91919 10 10 2021 22 27 27 28 3030 3 7 5 8 17 10 16 18 22 2023 23 27 25 I I 4 8 12 14 17 19 26 25 8 7 

 I003 1632 I540 2139 RS9 2168 2197 2547 2561 1665 1573 1675 2225 2226 2814 1535 1543 1297 2503 1154 2004 I720 1351 

 2478 523 S 2513 537 S 305 W540W542 2567 IS07 349 512 616 522 527 25902594 368 24 36 656 207 



(3) 

 '^^ o 50 100 



f.",'" i WEDDELL DRIFT 

 ^H EAST WIND DRIFT 



n 



(0(0 



(0(1) (0 



(I) (2) (2) (2) (2) 



Scale per cent 

 (0 (2) (0(0(0 



121 I570 1637 256 46 61 174 245 345 205 186 82 85 200 146 ISO 100 75 416 269 527 95 lOO 

 310 100 57 189 379 325 20 522 lOO 818 lOO 35 517 lOO 100 lOO 388 176 63 84 lOO 231 102 



STATION 



66 

 64 

 60 

 55 

 52 

 48 

 44 

 40 

 36 

 32 

 28 

 24 

 20 

 16 

 12 

 8 



N?MEAS- 

 -URED 



^ SAMPLE FROM SIGHTED SWARM 



Fig- 57- Developmental condition of adolescent swarms in the East Wind drift, showing the corresponding condition of 

 adolescent swarms found in the Weddell drift at the same, or approximately the same, time. Note vertical scale in 4-mm. 

 groups, e.g. 20 = 17-20 mm. 



zone. During the long period, June to December, when the East Wind drift is virtually closed to 

 navigation, the modal values must be correspondingly low, a single observation in December^ giving 

 some indication of how low they might be. In other words it is clear from Fig. 55 that in the 

 East Wind zone although some of the swarms attain the modal stature of their northern counterparts, 

 a high proportion of them, to all appearances throughout life, never do. It is also clear that the avail- 

 able feeding-stuff for the whales that reach these high latitudes must often consist of considerably 

 smaller animals than they would normally encounter in the northern zone. 



More striking illustrations of how the East Wind swarms persistently lag behind their northerly 

 contemporaries, in both stature and development, are given in Figs. 56 and 57, the former 



1 Obtained from a factory ship which (p. 124) had forced a passage through the ice to a position not normally attainable 

 by a vessel such as 'Discovery II'. 



