LUX: AGE AND GROWTH OF WINTER FLOUNDER 



sidered to be the annulus. Slight checks in 

 growth consisting of only a few closely spaced 

 circuli were considered to be false annuli and 

 were ignored in assigning age. In the first year 

 all circuli are closely spaced. The annulus here 

 was taken to be the outermost of these circuli. 



Ages were assigned to each fish by the 

 author and, independently, by an assistant. 

 For some scales reliable growth calculation 

 appeared impossible because of regeneration, 

 erosion, resorption, or checks. These, making up 

 about 15% of the total sample, were omitted 

 from the calculations. As might be expected, 

 the proportion of rejected scales was much 

 higher for large fish (Table 1). 



Table 1. — Length-frequency distribution of winter flounder 

 collected on Georges Bank in 1963-66 and proportions 

 included in the growth calculations, by 5-cm intervals. 



Age was determined, to the extent possible, 

 for the rejected scales and length at age of 

 these fish was compared with that of fish 

 included in the growth calculations to determine 

 if bias was introduced by the rejection of part 

 of the sample (Figure 3). While the samples 

 were rather small in the older ages, there 

 appeared to be no difference in growth of the 

 two groups offish. 



Totals of 412 fish from eastern Georges 

 Bank and 98 from western Georges Bank were 

 included in the calculations. All of the commer- 

 cial samples, consisting of 225 fish, were from 

 eastern Georges Bank. 



Length at each annulus was calculated from 

 measurements of anterior scale radii. The re- 

 lationship of body length to scale length ap- 

 proximated a straight line, except for curvi- 



i 



6 8 10 



AGE IN YEARS 



Figure 3. — Mean lengths at capture by age group for 

 fish from commercial samples included in growth calcu- 

 lations (circles) and those rejected (triangles). (Open 

 symbols represent fewer than three fish.) 



linearity among the smallest fish (Figure 4). 

 Direct proportion growth calculations therefore 

 were made using the equation 



/. 



c + 



(l-C) 



where /^ is the fish length at the time of 

 formation of the nth annulus, C is the fish 

 length at scale formation, S^ is the anterior 

 scale radius to the /;th annulus, S is the 

 anterior scale radius at capture, and / is the 



Z 150 



• /'^ ^v = 20.e *0.3 



300 400 500 



FISH LENGTH IN MILLIMETERS IXI 



Figure 4. — Body-scale relationship of Georges Bank 

 winter flounder based on measurements of 101 fish. 



507 



