74 
Burr, Kuhajda, Dimmick, and Grady 
presumably similar to the variable, slight seasonal increase in other 
species (Mayden and Burr 1981; Burr and Mayden 1982a, b). 
GSI of mature females reached a peak in May (x GSI r 176) and 
June (x GSI = 166) and began to taper off in July (x GSI = 105). Peak 
GSI in May and June presumably corresponds to accelerated ovarian 
recrudescence and oocyte vitellogenesis. Sixteen gravid females had a 
mean adjusted body weight of 7.60 gm and a mean ovarian weight of 
1.04 g (range = 0.34 to 2.34). The proportionally heaviest ovaries 
(equaling 25.8% adjusted body weight) were those of a 70-mm female 
collected from the Little River on 19 May (Table 1). GSI ratios from 
gravid females of other medium-size to large madtoms collected May 
through July were: 79 (N = 4) in N. nocturnus (Burr and Mayden 
1982b), 107 (N = 7) in N.flavater (Burr and Mayden 1984), 145 (N = 12) 
in N. miurus (Burr and Mayden 1982a), 149 (N = 33) in N. gyrinus 
(Whiteside and Burr 1986), 175 (N = 3) in N. flavipinnis (Shute 1984), 
and 21 1 (N = 11) in N. exilis (Mayden and Burr 1981). 
Externally, gravid females appeared similar to immature specimens 
except in having distended abdomens and swollen genital papillae 
(Fig. 6). 
Oocyte Diameter and Fecundity. As in congeners, ovaries of gravid 
females contained two size classes of oocytes. Large, vitellogenic oocytes 
were amber, ranged in diameter from 1.7 to 3.0 mm (x = 2.5; N = 130), 
and were assumed to be the only oocytes spawned during one season. 
Immature oocytes were small (0.2 to 1.8 mm; x = 0.9; N = 12) and 
opaque white or yellow. In 17 gravid females there was a positive 
correlation (r = 0.97) between mean oocyte diameter in mm (D) and 
increasing GSI, with D = 1.46 + 0.006GSL 
Vitellogenic oocytes in 17 gravid females ranged in number from 79 
to 298 (x = 126.3). Asymmetry in oocyte number between right and left 
ovaries occurred in several females, but the differences were not 
statistically significant at the 0.05 level (Table 1). Skewed distributions 
of oocytes have also been reported for N. exilis (Mayden and Burr 
1981), N. flavus (Walsh and Burr 1985), and N. flavater (Burr and 
Mayden 1984). As suggested by Walsh and Burr (1985), these differences 
probably reflect individual variation since other gravid N. furiosus had 
nearly equal numbers of oocytes between ovaries (Table 1). 
The total number of mature oocytes in a female was positively 
correlated with increasing SL, adjusted body weight, and age. For 17 
gravid females, the regression of number of mature oocytes (F) on SL 
was F = -248.60 + 5.0 1SL (r = 0.81), of the number of mature oocytes on 
adjusted body weight in grams (W) was F = 16.37 + 14.47W (r = 0.90), 
and of the number of mature oocytes on age in years (A) was 
F = -140.30 + 87.04A (r = 0.77). The number of mature oocytes per gram 
adjusted body weight ranged from 12.2 to 24.1 (x= 17.1; N = 16). 
