BOLZ AND LOUGH: GROWTH OF ATLANTIC COD AND HADDOCK 



E 



JZ 



4-> 



m 



c 



Q) 



XI 



O 



X) 



c 



D 

 C/) 



200.0 - 



100.0 - 



50. - 



25.0 •- 



12.0 



6.0 - 



3.0 - 





ln(L) = 1.3915 * 6.2707(1 - g-°-°°53Rj 



J I \ L 



J I L 



J 1 L 



J I L 



25 



50 



75 



100 



125 



150 



175 



AgG in Days 



Figure 4. — Gompertz growth ciirve and equation fitted to plot of In standard length and number of otolith increments (estimated age 



in days) for 157 larval and juvenile Atlantic cod collected on Georges Bank. 



Table 3. — Mean standard length at age, 95% confidence limits, 

 and growth rate (mm/day and %/day) of larval and juvenile Atlantic 

 cod from hatch through 200 days estimated from the Gompertz 

 growth model fit. 



Figure 7 shows the Atlantic cod growth curve 

 bracketed by 95% confidence intervals. Tables 4 

 and 5 provide predicted ages of Atlantic cod and 

 haddock for given standard lengths with 70% and 

 95% confidence limits. 



Otolith Growth 



In the earlier study of larval Atlantic cod and 

 haddock (Bolz and Lough 1983), it was found that 

 the sagittal rings (one incremental and one dis- 

 continuous zone) were segregated into distinct re- 

 gions separated by thicker, darker discontinuous 

 zones referred to as checks or check rings. Two 

 "heavy rings" were noted in the larvae: 1) a nu- 

 clear check surrounding a central, amorphous 

 core and 1 or 2 irregular rings, and 2) a yolk-sac 

 check 2-8 increments farther outward (Fig. IB). 

 The present study corroborated the existence of 

 these two checks. Although each otolith was care- 

 fully examined for the presence of a settling 

 check, no regularly occurring heavy ring could be 

 discerned beyond the yolk-sac check in either the 

 haddock or the Atlantic cod juveniles. It should, 



229 



