Biology of Etheostoma rufilineatum 73 



during the study. Large males (longer than 50 mm) occurred consis- 

 tently in the swiftest sections of riffles; smaller males and females were 

 collected in swift riffles during summer, but were found frequently in 

 areas with moderate current or along the margins of riffles in other 

 seasons. Young-of-the-year darters were not well represented in sam- 

 ples, and were generally found in protected areas with low current veloc- 

 ity, adjacent to emergent vegetation or streamside brush. Larval darters 

 apparently drift passively into pool areas (Scalet 1973) and have been 

 found at depths of 3 meters (Stiles 1972). The habitat of redline darters 

 in the North Fork Holston River concurs with that reported for other 

 Nothonotus species (Raney and Lachner 1939; Raney and Suttkus 1964; 

 Zorach 1969, 1970). 



Age and Growth 



Scale radius and total length of fish were strongly correlated (r = 

 0.85, females; r = 0.93, males). Regenerated scales were common on fish 

 of all sizes, but at least three readable scales were available from each 

 fish collected. Annuli were recognized by crowding of circuli in the 

 anterior field and cutting over in the lateral field. Annulus formation 

 was in early to mid-March at water temperatures of 5° to 20° C, as is 

 typical of other darter species (Fahy 1954; O'Neil 1981; Shute et al. 

 1982). The body-scale relations for males and females were linear. Equa- 

 tions for the fitted regression lines were as follows: 



Males L = 14.3 + 0.619 (S) (R 2 = 0.859) 

 Females L = 10.0 + 0.708 (S) (R 2 = 0.720) 



where L = total length (mm) and S = scale radius magnified (focus to 

 margin in the lateral field in mm). Back-calculated lengths, based on 

 scale measurements, approximated actual lengths of darters at capture 

 for all age classes (Table 2). Length-frequency distributions for males 

 and females did not provide an adequate indication of age class struc- 

 ture. Scale readings were assumed to be accurate because a random 

 sample of 30 scales was aged, with few discrepancies, by several fishery 

 biologists. Young-of-the-year darters appeared as an identifiable age 

 class in June, but overlap between lengths of 40 to 60 mm obscured 

 separation of the intermediate age classes (I and II). Scale analysis indi- 

 cated that maximum age for males and females was four years and three 

 years, respectively. Chapman-Robson estimates for annual survival were 

 0.28 (±0.003) for males and 0.03 (±0.001) for females. 



Growth of redline darters was rapid and uniform for all age classes. 

 Because only one age III female (67 mm) was collected, length-at-age 

 data were insufficient to obtain a reliable growth equation for females. 

 The von Bertalanffy growth parameters for males were as follows: 



L- = 88 mm, t = -0.815 years, K = 0.378 



