collected on October 14, 11 percent; on April 28, 19 
percent; on May 27, 15 percent; and on June 8, 21 
percent. 
The Reproductive Cycle of the Female 
No difference between the pigmentation of breeding 
females (Fig. 3) and that of non-breeding females was 
) 
Fig. 4.— Urogenital papillae of: A, male in the fall; B, 
male in the spring; C, female in the fall; and D, female in the 
ring. 
7 
discernible. Sexual dimorphism in P. phoxocephala 
seems to be limited to the contrast between the “normal” 
pigmentation of P, phoxocephala and the pigmentation 
of breeding males, the difference in breast squamation, 
and the presence of the specialized scales on the mid- 
belly of males versus their absence on females. 
In the spring the genital papillae of females were 
enlarged, striated, conical structures (Fig. 4). In the 
fall the papillae of females were morphologically similar 
but proportionally much smaller than those of specimens 
taken in the spring. 
Females having attained a standard length of at least 
42 mm were sexually mature at 1 year of age. All 
spring-captured females examined that were 42 mm or 
larger contained ova at least 1 mm in diameter and 
were ready to spawn. The only sexually immature 
spring-collected female was a 38-mm specimen collected 
on May 27, 1969. 
The prespawning period was characterized by the 
differentiation and maturation of ova: the spawning act 
by the release of mature eggs; and the postspawning pe- 
riod by the absorption of the remaining ova and recovery 
of the ovaries. In P. phoxocephala, the recovery time 
for females was very short, and enlargement of the ova- 
ries began soon after spawning (Table 1). 
Early stages of ova maturation proceeded slowly, but 
as spawning time approached, development was rapid. 
The growth of ova was reflected in an increase in the 
weight of the ovaries, which, in relation to body weight, 
showed an exponential increase between July and the 
following June (Fig. 5). 
As with other fishes, developing ova were easily cate- 
gorized into three groups based on size and color: the 
smallest ova were white and less than 0.5 mm in diam- 
eter; the intermediate were between 0.6 and 1.0 mm and 
yellow; and the largest were 1.1—1.3 mm and yellow 
to orange in color. 
Ova categorized as intermediate were present in a 
February-collected female (Table 2); large ova first 
appeared in April. The proportion of small ova de- 
creased as spring approached, and the proportion of 
large ova increased. The number of intermediate ova 
TABLE 1.—Lengths and weights of ovaries of Percina phoxocephala collected in different months of the year. 
Length in mm 
Weight in Grams 
Standard Length Ovary Length Adjusted Weight Ovary Weight 
Length of as Percent of Weight? of Both as Percent of 
Collection Date of Female Ovary Standard Length of Female Ovaries Adjusted Weight 
ily 21, 1959 67 13 19.4 3.66 0.02 O.8 
ugust 23, 1967 5 9 16.4 2.08 0.02 0) 
sptember 1, 1967 54 8 14.8 1.82 0.02 Hh, i 
ctober 22, 1967 57 11 LORS 239 0.06 ao 
ovember 8, 1963 66 14 2 3}, 0.09 30) 
ebruary 23, 1969 58 13 22.4 2.40 0.12 Doll) 
pril 28, 1968 44 12 Pas 3) 1.00 OnL2 12.0 
lay 27, 1969 56 14 25.0 2.30 0.35 15.2 
ine 8, 1969 60 18 30.0 2.59 R52 20.1 
* Adjusted weight is the weight of the female minus the ovaries, stomach, and intestines. 
