Rutherford and Houde: The influence of temperature on growth of Morone saxatilis 



321 



The larval growth rate estimates of Upper Bay 

 cohorts in 1989 did not differ significantly (P>0.25) 

 and ranged from 0.21 mm-d" 1 for larvae hatched on 8 

 May to 0.32 mm-d" 1 for larvae hatched on 1 June (Fig. 

 5). The mean cohort growth rate was 0.25 ±0.03 mm-d" 

 1 . Predicted mean lengths at 20 days posthatch of the 9 

 cohorts ranged from 7.4 to 10.0 mm. Predicted ages at 

 8.0 mm SL ranged from 14.8 to 22.1 days (Fig. 5). 



Back-calculated growth rates of 5-20 days 

 posthatch larval cohorts from the Potomac River 



ranged from 0.19 to 0.46 mm-d" 1 in 1987 (mean=0.27 

 ±0.05 mm-d" 1 ), from 0.18 to 0.34 mm-d" 1 in 1988 

 (mean=0.23 ±0.04 mm-d" 1 ), and from 0.11 to 0.36 

 mm-d" 1 in 1989 (mean=0.23 ±0.04 mm-d" 1 ) (Fig. 6). 

 Back-calculated growth rates of Upper Bay larvae, 

 available only for 1989, ranged from 0.18 to 0.36 

 mm-d" 1 (mean=0.26 ±0.03 mm-d" 1 ) (Fig. 6). 



The differences in back-calculated growth rates 

 among cohorts in each year resulted in different pre- 

 dicted lengths at 20 days posthatch. There were 



