FISHERY BULLETIN: VOL. 80, NO. 3 



White perch of age groups 3 and older completed 

 the annulus ~2 wk later. 



Length-Frequency and 

 Age Distribution 



During May and June, there were three modes 

 in the length-frequency data, with peaks at 65.0- 

 69.0, 105.0-109.0, and 140.0-144.0 mm (Figs. 2, 3). 

 These peaks represent the 1-, 2-, and 3-yr age 

 groups. From July to November the length fre- 

 quencies ranged from 10.0-14.0 mm to 200.0- 

 204.0 mm (Fig. 4). The prominent mode at 50.0- 

 54.0 mm represents young-of-the-year fish (Fig. 

 5). 



Growth 



The relationship between anterior scale radius 

 and standard length for white perch from all 

 age groups was L = 32.64 + 45.56 {R), where L = 

 standard length in millimeters and R = scale 

 radius in millimeters. The coefficient of deter- 

 mination (r 2 ) was 0.88 (Fig. 6). 



The standard lengths at the various annuli 

 were back-calculated and the growth histories 



were constructed for each year class, along with 

 growth increments for each age group (Tables 2, 

 3). The most rapid growth occurred in the first 

 3 yr of life, and accounted for 78.0% of the total 

 growth at the maximum size observed. Subse- 

 quent average growth increments were uniform 

 among year classes, but considerably smaller 

 (Fig. 7). Similar growth histories were compiled 

 for each year class for both male and female 

 white perch (Tables 4-7). Females grew slightly 

 larger in TL than males of the same age (Fig. 8). 



Length Conversions 



We calculated the relationship between total 

 length, fork length, and standard length mea- 

 surements taken on a subsample of 310 white 

 perch, ranging in size from 30.0 mm to 182.0 mm 

 SL. A linear regression was computed to obtain 

 conversions between the three methods so that 

 we could compare growth rates among the dif- 

 ferent white perch studies. (Fig. 6). The relation- 

 ship between total length and standard length 

 was SL = -1.05 + 0.81 TL, r 2 = 1.0; the relation- 

 ship between fork length and standard length 

 was SL = -0.99 + 0.86 FL, r 2 = 1.0. 



Length -Frequency Distribution 



Total #Fish = 1959 (May- June 1970) 



Male = *- 

 Female = 

 Total = 



s 



CM 



6 

 o 



CO 



Figure 2.— Length-frequency distribution of white perch during May and June 1970, and for mature males and 



females during this same period. 



602 



