LOlHill KT AI..: ACK AND GROWTH OK LARVAL ATLANTIC HERRING 



5 

 o 



3 

 ca 



_c 

 o> 

 3 



.2" 

 o 



o 



~ 5 



CD TO 



c aa 



P CO 



be CD 



c be 



O s_ 



- * 



° i 



■s ° 



c O 

 * a- 



o c- 



-a 



cd 



8 >> 



t« "^ 



C efl 



CD a> 



E *. 



.S a) 



o *j 



cu c 

 &•- 



en £ 



be j 



S be 



l- 3 



t. O 



cd j- 



J= -C 



ca <x> 



> t- 



ca i—* 



Z s 



c 3 



O 3 



ca 



ca 



.o 



c 

 o 



ca 



(72 



W 

 J 

 CO 



< 



o c » 

 ra - E 



CD O CD 



CO ~ ~ 



T3 Ol E 



<= C F 



m cd cz 



O - S 



Z™ 2 



EO o 



c5° C\J 



E^ 



g^E 



o m 



CD i 



m 



55 



„.2>S 



Is' 



PI 



Q O 



2 O 

 to s 



Eg 

 o 



p O CO CO 



to ^ oS <x> 



— . o — • 



a> a) co *— 



— o —CD co o 



CO O CO CM i- CO N CD tJ; 



cDtbcsjco cnj r^ ^ cm ■<t 



cm o to •*- ^r 

 oS r*- ^ c\i crt 



\J1 \t^ 1.1* *."/ >. M I - I V H -* ^ V* I — -» »  -*• 



t-i-C\JCM I- CM ^t CM CNJ tJ O CO *~ CN CNJ 



r- r- co cm r^. 



CM ^ CM CO i- 



•^ CO CD CO O 



CM O *- i- c\i 



cm -<t h- co ^r 



CM i- O CM I CM 



m n i- in a> 

 in ^ 



co t- o w o oir^p'- cm 



r^ -(J- N r- CO CO r- CJ) CO CO CO o 

 i- i- t-CMi-^-CM CM CM CM CM CO 



lO O) O) S CO 

 CO CO CO t- 



O) p O h-- 

 CM CO CO C\i 



o cp ^r in tt 



CO CO s s cb 



cd o m p 



O O CO CO 



ZQQZ Z ZZZZZ ZZQO Q 



o m m o o cm to o o in t-cooco o 



Ot-i-co m ocsjcoom ocmcmco co 



CO^incO CD O ID O »- O) SOCOCD CM 



O'-'-O O OOt-i-O O *- *~ *- cm 



1^ 



CD 



OOOU O CDCDCUCDCD 0) <D CD CD J2 



OOOO O QQQQQ u_ ll u_ u_ 2 



w 



COCO^t 1 ^- i- »-»-C\ICO'- oococo 



a 



■c 

 o 





5 

 5 



CO 

 ■D 



c 



CO Q) 



to 3 



«~ 2 



en 5 

 > 

 CO co 

 CD 

 CO 0) 



^2 



C « 

 CD CD 

 CO g- 



a E 



E 2 



H CD 



.*: o 

 3 ™ 



E >■ 

 ZO 



ture data at each station were obtained from ex- 

 pendable bathythermograph traces or surface 

 bucket readings. 



Larvae were reared from fertilized eggs in the 

 laboratory in order to determine the age at which 

 increment deposition first begins in larval her- 

 ring otoliths. A batch of herring eggs, stripped 

 from several ripe and running adults collected 

 along the western Gulf of Maine near Jeffreys 

 Ledge, was fertilized on 17 October 1978 and 

 reared at the NMFS Narragansett Laboratory 

 at 10°C by G. Laurence for use in various feeding 

 experiments. Larvae were maintained in special 

 rearing aquaria described by Beyer and Laur- 

 ence (1981) with a photoperiod of 12 h light and 

 12 h dark and fed wild plankton at high den- 

 sities (>3 plankters/ml). Approximately 15 lar- 

 vae were removed from the rearing aquaria 

 daily from hatching on 28 October through 15 

 November and preserved in 75% ethyl alcohol. 



Prior to removing the otoliths, larvae were 

 staged according to Doyle (1977) and measured 

 for standard length (snout to caudal peduncle) 

 and head length (snout to sagitta in normal posi- 

 tion) to the nearest 0.1 mm. The largest otoliths 

 (sagittae) were removed from both sides of the 

 head when possible and mounted in Canada bal- 

 sam or Permount. 8 The otoliths were whole 

 mounted and little difficulty was found in read- 

 ing them intact so that further preparation was 

 unnecessary. The 2-sagittae and 2-astericae ob- 

 tained per individual from the laboratory-reared 

 larvae were virtually impossible to distinguish 

 at this early stage; however, the number of 

 growth increments was identical for both sets of 

 otoliths from the same individual. 



The otoliths were viewed by transmitted light 

 and growth increments were counted using a 

 Zeiss compound microscope-video system with a 

 magnification range of 630X for the largest oto- 

 liths and 1000X or 2000X for the smallest. Differ- 

 ential interference microscopy was particularly 

 helpful in distinguishing increments of the 

 smallest otoliths. The resolving power of our 

 microscope is in the range of 0.2-0.5 /nm. A mini- 

 mum of three counts was made on all otoliths or 

 counts were repeated until a mean value was 

 reached with a maximum acceptable range of 5% 

 variability. Routine otolith measurements made 

 to the nearest micron as illustrated in Figure 2 

 included the following: 1) anterior-posterior di- 



8 Reference to trade names does not imply endorsement by 

 the National Marine Fisheries Service, NOAA. 



189 



