Miller et al.: Relation between otolith size and larval size at hatching for Gadus morhua 



301 



100 200 300 400 



Sagittal area (nm^) 



500 



600 



65 r 



6 

 55 



5 

 45 



4 

 35  



3 

 25 



B 



O °o 



o °% 



'-ooj^'--- 



-r?"- 



10 12 14 



Radius of sagitta at hatching (urn) 



16 



Figure S 



Relation between size at hatching of individual larvae and (A) the sag- 

 ittal area (SA), and (B) the sagittal radius (SR) at hatching 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 SA = 4.033 

 (±0.21) + 0.00178 (±0.0007) X SL, n = 58, r^ = 0.09, P = 0.017; SR = 3.44 

 (±0.45) + 0.104 (±0.043) x SL, n = 59, r- = 0.09, P = 0.018. 



could predict overall mean population growth rates 

 extremely well but that they were unreliable predic- 

 tors of individual larval growth. For example, Geffen 

 (1995) reported that within 15 d of hatching, otolith 

 growth and a measure of somatic growth were poorly 

 correlated in cod larvae. If Geffen's conclusion reflects 

 a broad pattern, her results have profound implica- 

 tions for any application of an individual-based back- 

 calculation approach to cod. Recently, Meekan ( 1997) 

 pointed out that Geffen's conclusions may have been 

 affected by experimental conditions and by the use 



of a single mean value of larval size at hatching as 

 the origin of the relationship between larval size and 

 otolith size. Larval size at hatching varies substantially 

 in cod (Knutsen and Tilseth, 1985; Miller et al., 1995), 

 and thus Geffen's use of a single size at hatching is 

 unrealistic and cannot be supported by the data avail- 

 able. Yet it is not clear what value one should use for 

 the origin in backcalculating growth trajectories. 



Our data suggest that the wide variability in the 

 relationship between otolith size and hatching size 

 observed in cod will likely plague attempts to 



