120 
Jerry W. Nagel 
At the time of the April/May 1979 population estimates specimens 
less than 50 mm TL were mainly immature individuals ending their first 
year, whereas specimens more than 50 mm TL were mature individuals 
that were two years or older (Fig. 1), Mature specimens were equally 
abundant in the two sections, whereas the immature size class 
showed strikingly higher density in the exposed and disturbed habitat of 
section §2. 
DISCUSSION 
In this study one year old fish were all immature and most two year 
old fish were mature individuals in breeding condition (Fig. 1). This is 
similar to maturity patterns found by investigations in Michigan (Hann 
1927); New York (Koster 1936); Montana (Bailey 1952); Wisconsin 
(Ludwig and Norden 1969); and Washington (Patten 1971). Koster 
(1936), however, noted that the lake-dwelling form, C.b. kumlieni, 
appeared to mature at the end of its first year at an average TL of approx- 
imately 61 mm (conversion from standard length based on Bailey 1952). 
The sexual dimorphism in size found for breeding individuals in this 
study was noted in other studies (Flann 1927; Koster 1936, for C.b. bairdi 
but not for C.b. kumlieni: Simon and Brown 1943; Bailey 1952; Zarbock 
1952; Ludwig and Norden 1969). 
In this study spawning occurred at water temperature of 12° - 14°C 
during a one week period in early April. Previous investigations of 
spawning by C. bairdi reported water temperatures ranging from 
5° - 18°C and dates from late February to late May (reviewed in Ludwig 
and Norden 1962). Hann (1927) and Koster (1936) reported brief spawn- 
ing periods similar to the findings in this study, but Simon and Brown 
(1943), Bailey (1952), and Ludwig and Norden (1962) reported spawning 
periods of a month or more. 
Several authors presented information on the average number of 
enlarged follicles in gravid females for western and northern populations 
of C. bairdi (257, Hann 1927; 120 for C.b. bairdi and 135 for C.b. 
kumlieni, Koster 1936; 629, Simon and Brown 1943; 203, Bailey 1952; 
328, Ludwig and Norden 1969; 95, Patten 1971). Although no particular 
geographic pattern in this variation is evident in these populations, these 
estimates are consistently higher than fecundity estimates reported in this 
study (three separate estimates = 56, 57, and 68) even though the size 
ranges of gravid females were quite similar in all studies. Correlated with 
this, average follicle diameter in northeastern Tennessee (3.32 mm) was 
greater than diameters reported by other authors (2.0-2. 5 mm, Hann 
1927; 2.2 mm, Simon and Brown 1943; 1.88 mm, Ludwig and Norden 
1969). This correlation continues when comparing average egg size (in 
nest) and average hatchling size. In this study eggs averaged 3.73 mm and 
sac fry 9.8 mm. Corresponding estimates from other studies are; sac fry 
- 6.4 mm (Hann 1927); eggs ~ 2.6 and 2.7 mm, sac fry ~ 6.9 and 7.9 
mm (Koster 1936); 5-day fry 6.9 mm (Simon and Brown 1943); sac fry 
