284 



Fishery Bulletin 91(2), 1993 



A. Haddock 



2 -5mm 6 • 8 mm 



30 20 10 tO 20 30 03 02 0.1 01 0.2 03 



r] 



66/IOm 2 108/ 10m 2 



06/tOm 2 I8/I0m 2 



2- 5mm 6  8 mm 9 • 13 mm 



15 10 5 5 10 15 15 10 5 5 10 15 60 40 20 20 40 60 



J 



28/)0m 2 37/IOm 2 



I4/I0m 2 30/I0m 



98/IOm 2 213/IOm 2 



SALINITY (psu) 

 32 TJ0 2 46 8 3300 2 



14 -19 mm 20 -29 mm 



TEMPERATURES) 

 15 K) 5 5 10 15 6420246 5 10 IS 



TEMP/ 



| SAL, 



lO/IOm 2 62/IOm 2 



3/IOrn 2 14/IOfn 2 



Figure 2 



Mean day and night vertical distribution (i n/lOOnv 1 ) of (A) 

 haddock Melanogrammus aeglefinus and (B) cod Gadus 

 morhua size-classes of larvae collected by the lm- MOCNESS 

 on well-mixed Site 81-1 during 27-29 April 1981. Estimated 

 water column abundances (rc/lOnrl are included for day-night 

 comparisons at bottom of plots. Composite temperature and 

 salinity profiles are plotted as depth stratum mean (•) and 

 95^ confidence limits ( ). 



Mean depths of the four smallest cod size-classes 

 are plotted for each tow within a 24 h period over the 

 2.5 d of sampling at Site 81-1, and a trend line con- 

 nects the mean depths of abundance (Fig. 3). There 

 appears to be a daily pattern in vertical distribution. 

 The smaller size-classes, 2-5 mm and 6-8 mm, re- 

 mained at a depth of -35 m day and night. In contrast, 

 larger size-classes of cod, 9-13 mm and 14-19 mm, 

 showed a consistent diel migration from a mean depth 

 of 40 m at noon to 20-25 m after sunset. 



At the well-mixed shoal (35-58 m) Site 81-111 on 27 

 May 1981, 2-13 mm haddock and 6-13 mm cod lar- 

 vae were distributed through the water column (Fig. 

 4 1 with mean depths of abundance generally at 20 m 

 and 40 m. Because of the limited number of tows, a 

 significant difference in day-night patterns could not 

 be determined. 



TIMEth ) TIME(h) 



1200 1800 2400 0600 0600 1200 1600 2400 0600 



u;40 



0600 1200 1800 2400 0600 0600 1200 1800 2400 0600 



Figure 3 



Abundance weighted-mean depths (•) of larval cod 

 Gadus morhua size-classes plotted over a 24 h period 

 on well-mixed Site 81-1 during 27-29 April 1981. Line 

 connecting replicate points represents the average 

 population trend. 





3/IOm 2 04/IOm 2 

  Single night haul 



B Cod 



6 B mm 9  13 mm 



150 100 50 50 100 150 150 100 50 50 100 150 



203/IOm 2 73/ 10m 2 235/IOm 2 21 1/ 10m 2 



SALINITY(psu) 

 32 00 2 4 6 8 3300 2 







I 20 

 £30 



9 - 13 mm 

 4 4 



TEMPERATURE !°C) 

 5 10 15 



TEMpj 



5/IOm* 5/IOm2 



 SINGLE NIGHT HAUL 



I7/I0m z 29/IOm2 



Figure 4 



Mean day and night vertical distribution (.v n/100m') of (A) 

 haddock Melanogrammus aeglefinus and (B) cod Gadus 

 morhua size-classes of larvae collected by the lm- MOCNESS 

 on well-mixed Site 81-111 during 27 May 1981. Estimated 

 water column abundances (n/10m-) are included at bottom of 

 plots. Temperature and salinity profiles are plotted as depth 

 stratum means (•) and 95% confidence limits ( ). 



At the well-mixed shoal (34-54 m) Site 83-111 on 

 16-17 May 1983, three size-classes of haddock and cod 

 larvae (6-8, 9-13, 14-19 mm) were distributed through 



