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Fishery Bulletin 97(2), 1999 



This suggests that the observed check is deposited 

 at or immediately before yolksac absorption and that 

 the number of increments between the nucleus and 

 the absorption check reflects the duration of the 

 yolksac phase (Fridgeirsson, 1978; Laurence, 1978; 

 Fahay, 1983). 



Haddock and pollock larval and juvenile growth 



In recent years, the examination of otolith micro- 

 structure has resulted in many applications (Jones, 

 1992). The underlying assumption is that increments 

 form daily. In otoliths of haddock (A/, aeglefinus ), and 

 pollock {P. virens). increments are deposited daily and 

 thus can provide accurate estimates of age (Bolz and 

 Lough, 1983; Campana, 1989; Campana and Hurley, 

 1989). 



The estimates of haddock growth in this study are 

 comparable with those reported earlier. Thus, the 

 predicted length of 4.1 mm at hatching and the av- 

 erage growth rate of 0.65 mm/d for 0-4 mo old lar- 

 vae in the present study are similar to the values 

 reported by Bolz and Lough (1983, 1988). The ad- 

 justment of a Laird-Gompertz model (/■"=0.99) for the 



InSI =0 571nOD-0 48 

 F= 14689. PO 

 «=471. R=0 98 



1,000 2,000 3,000 4,000 5,000 



30 

 25 

 20 

 15 

 10 

 5 



100 200 300 400 500 600 



Sagittal maximum diameter (^m) 



Figure 5 



Standard length as a function of ma.ximum .sa^jiltal diameter 

 in larval pollock and haddock. 



entire data set correctly predicted length (Table 5). 

 Different patterns in growth occur during ontogeny 

 (Table 6). The average increase in length is moder- 

 ate between hatching and 50 d (0.27 mm/d), high for 

 early juveniles of 2.5-3 mo (0.68 mm/d), and moder- 

 ate again (1.2 mm/d) for older juvenile. Few studies 

 provide estimates of the age and growth of larval and 

 juvenile pollock (Campana, 1989). The predicted 

 length at hatching was 4.5 mm and the average 

 growth rate of larval was 0.22 mm/d during the first 

 3 mo. The Laird-Gompertz model (r-=0.98) applied 

 to the entire set data adequately described growth. 

 A slow increase in length occurs during the first 30 d 

 after hatching (0.18 mm/d ), and then the rate is mod- 

 erate during the following 1 to 2 mo (0.23 mm/d). 

 Finally, a stable period (0.24 mm/d) begins (Table 6). 

 In the present study only the pelagic phase prior to 

 metamorphosis and beginning of demersal life was 

 examined. Nevertheless, sampling continued 

 throughout the year and older pollock juveniles up 

 to 80 d old (23 mm SL) were captured. The last pol- 

 lock samples were collected in 1993. Juvenile pol- 

 lock probably move from the oceanic zone to the shal- 

 low coastal zone after metamorphosis (Scott and 

 Scott, 1988). Campana (1989) collected 53 pol- 

 lock juveniles from the north shore of Gran 

 Manan Island, New Brunswick, on August 1984, 

 and the mean length of juveniles was 97.3 ± 1.9 

 mm. The date of capture of Campana's samples 

 suggest that pollock juvenile move to the Scotian 

 shore, possibly toward the Bay of Fundy, to fin- 

 ish their development. If pollock sharply increase 

 their growth rate in response to improved feed- 

 ing conditions during demersal lifestyle, as we 

 observed for haddock, they could attain an aver- 

 age length of 106 mm by August, a size similar 

 to that of juveniles collected by Campana. Growth 

 rates (mm/d) varied significantly in different 

 years, and the rates of the two cohorts showed 

 an alternate pattern: growth was higher for the 



1992 cohort during the first 45 d and higher for 



1993 cohort following the first 45 d. The 1993 

 cohort was first detected two months later than 

 the 1992 cohort. The adjustment of a Laird- 

 Gompertz model (r^=0.98) to each annual data 

 set closely predicted length (Table 5). 



Growth during the juvenile period of haddock 

 and pollock can be divided into a series of "stan- 

 zas." The change from one stanza to the next is 

 characterized by a discontinuity in development, 

 such as during hatching or after a change of habi- 

 tat (Ricker, 1979). Growth accelerates abruptly 

 in fish older than 50 d in response to a shift from 

 a pelagic to a demersal diet. Because we captured 

 juvenile pollock immediately after the transition 



