14 
Fred C. Rohde and Steve W. Ross 
Fig. 6. Annual growth of Etheostoma mariae males and females from Naked 
Creek, North Carolina. Solid line = range; triangle = mean; rectangle = 95% 
confidence interval. 
Regression of standard length onto scale radius (SR) yielded the 
formula: SL = 7.47 + 0.83 SR, r = 0.97. This was used to back-calculate 
to size at annulus formation by inserting measurement to annulus in 
place of scale radius. Back-calculated sizes at age 1 from age classes 1 
and 2 were in close agreement with observed standard lengths (Table 3) 
with only a slight tendency toward Lee’s phenomenon, which we attrib- 
uted to selective natural mortality favoring survival of younger fish 
(Bagenal and Tesch 1978). Back-calculation indicated a small mean 
growth increment between ages 1 and 2 of 13.7 mm for males and 11.2 
mm for females (Table 3). 
Rapid growth of young-of-the-year darters is typical (e.g. Raney 
and Lachner 1943, Burr and Page 1978, Pflieger 1978, O’Neil 1981, 
Shute et al. 1982). Growth differences by sex were not significant in 
immature E. mariae', however, males were significantly larger when fish 
were older (Fig. 6). Males of the related E. okaloosae are also larger 
than females (Collette and Yerger 1962). Raney and Lachner (1943) and 
Lachner et al. (1950) have shown that this is a common phenomenon 
for species in which the male guards spawning areas. Page (1974, 1975) 
and Page and Burr (1976) found that mature males were larger than 
females in several members of the subgenus Catonotus ( E . squamiceps. 
