Biology of Etheostoma rufilineatum 1 1 



Table 1. Water chemistry characteristics collected monthly at North Fork Hol- 

 ston River Mile 86.9, January 1981-March 1982. 



Characteristic 



Mean 



Range 



N 



Hardness (mg/ 1) 



130 



90-175 



12 



Alkalinity (mg/ 1) 



116 



70-160 



14 



pH 



7.1 



6.6-8.3 



12 



Dissolved oxygen (mg/ 1) 



9 



7-12 



12 



Turbidity (FTU)* 



14 



0-25 



11 



Conductivity (/imhos) 



143 



81-218 



12 



* FTU = Formazin turbidity units 







stomach contents before preservation in 10% buffered formalin. Preser- 

 vation produced a mean shrinkage of 2 mm in length and gain of 0.2 g 

 in weight. In the laboratory, the preserved fish (499 males, 183 females) 

 were measured (total lengths to nearest 1.0 mm) and weighed (to nearest 

 0.1 g). 



Age and Growth 



Scale samples from 126 males and 65 females were taken from the 

 left side above the lateral line and below the spiny dorsal fin at the tip of 

 the depressed pectoral fin, mounted on optical plastic slides, and exam- 

 ined under a compound microscope at 10X magnification. Measure- 

 ments were made with an ocular micrometer from the center of the 

 focus to each annulus and to the scale margin in the anterolateral field. 

 Length-frequency distributions were plotted as a check on scale read- 

 ings. Age and growth data for males and females were analyzed using a 

 computer program developed by Marques et al. (1982). Regressions for 

 body length-scale radius relation were fitted by linear regression and 

 length-weight relations were computed. Growth curves were fitted to the 

 von Bertalanffy growth equation (Ricker 1975): 



where L t = total length (mm) at time t, L^ = asymptotic length (mm), K 

 = growth coefficient, t = time (age), and t Q = hypothetical age at zero 

 length. Annual survival of males and females was computed by the 

 unbiased minimum variance estimator of Chapman and Robson, which 

 is based on coded ages and the frequency of individuals in each age class 

 (Everhart et al. 1975). Since age and I fish were less vulnerable to the 

 sampling gear, they were not included in these survival estimates. 

 Food Habits 



Ten darters per month, sampled randomly from collections made 

 during each sampling period, were dissected to determine seasonal food 



