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Fishery Bulletin 97(2), 1999 



n=8, r^=0.99) were used to calculate the unpresei-ved 

 standard length (SL) offish preserved in ethanol. 



Validation of ageing technique 



To determine if the increments observed in otoliths 

 of haddock and pollock were deposited daily, fertil- 

 ized eggs collected in a 333 yim mesh net from the 

 RMT were reared on the ship. Haddock eggs were 

 collected at the Western and Emerald Banks area, 

 February-April 1992 and 1993. Spawning begins in 

 February around the Western Bank. Eggs were taken 

 in the same general area on any given sampling date 

 from February to April in both 1992 and 1993. 



Some pollock eggs were collected in January-Feb- 

 ruary and April 1992, as well as in October-Novem- 

 ber 1992 and January and March 1993. At the be- 

 ginning of the spawning season, eggs were detected 

 at the southeast of Sable Island Bank. In January- 

 February the eggs were collected on the Western 

 Bank, and in March-April the distribution of eggs 

 included Emerald Bank. The spawning of pollock and 

 haddock overlapped during February-April because 

 the eggs of the two species were found together. 



Immediately after the nets were brought aboard 

 the vessel, the most advanced stages of eggs were 



sorted and individually placed in 20-mm vials filled 

 with seawater which had been passed through l-|im 

 Hytrex filters. At this time it was impossible to dis- 

 tinguish between the eggs of the two species (Brander 

 and Hurley, 1992). They were reared at 4°C in a con- 

 ventional refrigerator on the ship. The photoperiod 

 was kept at 12:12 h with dim blue light. As each egg 

 was monitored twice daily to establish when hatch- 

 ing occurred, the maximum error in hatching time 

 determinations was 12 h. After hatching, 136 zero to 

 eleven-day haddock larvae, and nine zero to four-day 

 pollock larvae were killed and preserved in 959i etha- 

 nol. Twelve additional 0-2 d old haddock larvae (col- 

 lected on April 1993) were obtained from Flodevigen 

 Marine Research Station, in Arendal, Norway. A to- 

 tal of 148 haddock larvae and 9 pollock larvae were 

 used to examine increment formation. Because had- 

 dock and pollock eggs were indistinguishable; individu- 

 als were later identified by their larval characteristics. 



Otolith preparation 



A dissecting microscope illuminated with polarized 

 light was used to dissect the sagittae and lapilli from 

 larval skulls with the aid of fine needles. One thou- 

 sand two hundred and sixty pairs of haddock and 



