300 



Fishery Bulletin 97(2), 1999 



65 



6 

 5.5 



5 

 4.5 



4 

 35 



3 



E 25 



O OqOc 



^ 200 



0) 



300 400 500 600 700 



Laplllar area (fjm^) 



800 



900 



3  

 2.5 - 



10 12 14 16 18 



Radius of lapillus at hatching (|im) 



20 



Figure 4 



Relation between standard length (SLi at hatching of individual larvae 

 and (Ai the lapillar area iLAl. and (B) the lapillar radius at hatching (LRi 

 for newly hatched cod larvae on the Scotian Shelf Shown on each plot are 

 the predicted linear relationships and 95'; confidence intervals of the mean 

 and of individual predictions. Regression relationships are LA = 3.295 

 (+0.24) + 0.0023 (±0.0004) x SL, n = 54, r- = 0.35, P = 0.0001; LR = 1.898 

 l± 0.51) + 0.188 1+0.036) V SL. n = 54, r- = 0.35, P = 0.0001. 



lus were more accurate than those involving the ra- 

 dius of the lapillus at hatching. We conclude from 

 these findings that attempts to hindcast size at hatch- 

 ing in cod should rely on measurements taken from 

 the lapillus and, where possible, should use the cross- 

 sectional area of the otolith as the measure of otolith 

 size. It has been recognized thpt cod lapilli are larger 

 initially than sagittae, but that sagittae increase in 

 size more rapidly (Bergstad, 1984; Radtke, 1984; 

 Campana and Hurley, 1989). Lapilli remain larger 

 than sagittae for up to 25 days. As a result, back cal- 



culations involving cod older than 25 d or larger than 

 6-8 mm have been based on sagittae instead of lapilli. 

 However, the relative sizes of the otoliths at their 

 core remain unaltered by subsequent growth dynam- 

 ics. Hence, we caution that, even though the sagittae 

 in these larger and older fish are larger absolutely 

 than the lapilli, the precision of estimates of initial 

 size at hatching will be most precise if the estimates 

 are based on the size of the lapillus at hatching. 



In controlled laboratory experiments, Geffen ( 1995) 

 found that the otolith-size and fish-size relationship 



