Hayse Feeding, age. growth, and reproduction of Chaetodipterus faber 



75 



Figure 7 



Mean marginal increments, in ocular units, on the 

 otoliths of Chnetndipterus faber by month of cap- 

 ture in South Carolina. Heavy horizontal bars repre- 

 sent mean values, heavy vertical bars represent 95% 

 confidence intervals, and vertical lines represent 

 ranges of measurements. Numbers over each series 

 of values are sample sizes. 



November (Fig. 7). Although a marginal increment of 

 zero was never observed, there was a strong indica- 

 tion that the opaque zones on the sagittae formed once 

 a year between December and April, and, therefore, 

 justified their use as annular marks. However, these 

 were months when Atlantic spadefish were absent 

 from collection sites and, consequently, no specimens 

 were obtained. 



The oldest fish was age 8, although no age-7 fish were 

 collected. Observed mean lengths (TL and SL) and 

 weight increased with age (Table 2), and ail least- 

 squares regression relationships were very highly 

 significant (P<0.001) (Table 3). Analysis of the age 

 composition of Atlantic spadefish by stratum showed 

 that all fish taken in stratum 1 were young-of-the-year 

 (age 0) and the fish from stratum 2 were predominantly 

 age 1, although age-0 fish were seen in stratum 2 in 



increasing numbers from late summer to late fall. All 

 fish taken on the artificial reefs (stratum 3) were age 

 2 or older. 



Mean back-calculated TLs at age were lower than 

 mean observed TLs for all age groups Mean back- 

 calculated lengths at preceding annuli, weighted mean 

 back-calculated lengths, and growth increments for all 

 fish age 1 and older are in Table 4. Growth rates dif- 

 fered little between sexes. The von Bertalanffy growth 

 equation, derived from back-calculated mean total 

 lengths at age was: 



I, = 490(1 - e-o.34(/ + o.i8))_ 



where t is age in years and /, is total length at age 

 (Table 5). There was good agreement between the 

 mean observed, mean back-calculated, and theoretical 



