8 
interrupted much of the spawning and_ reproductive 
success was reduced from 1965 (Table 4). 
_ Reproduction of P. phoxocephala was later than for 
P. maculata. When floods occurred around the first 
of June 1965, reproduction of P. phoxocephala was 
poor. In 1966, high water came in April and May 
but was lower by June. Reproduction was greatly im- 
proved over 1965 (Table 4). 
The large range in size of yearling P. phoxocephala 
(34-57 mm on April 18, 1966) indicated an extended 
spawning period. Another indication was the condi- 
tion of a few females collected in August; they still 
had enlarged ovaries. One 80-mm_ female collected 
below Carlyle as late as August 11, 1965, had about 
330 medium to large eggs. At Vandalia on August 
5, 1965, three females had enlarged gonads with eggs. 
Though most of these eggs showed resorption, one 
female had two milky white eggs in the urogenital 
opening. Gonad weight in these females comprised 
about 6 percent of the total body weight, whereas 
others taken at the same time had reduced ovaries 
which comprised less than 0.5 percent of the total 
body weight. No males collected in August showed 
enlarged testes. 
Winn (1958)) reported P. caprodes spawning over 
gravel and small rubble in riffles and raceways with 
fast current. The eggs are partly buried in the gravel 
during fertilization and are then abandoned (Winn 
19582). In the Portage Lake outlet (Michigan) they 
spawned from April 1 to June 1. The fact that no 
P. caprodes were collected in spring in the Kaskaskia 
suggests that they were spawning in deeper chutes or 
pools where collecting was difficult. Young-of-the-year 
were collected on June 16, 1966, in the Carlyle area. 
One fish 29 mm and another 50 mm long may have 
represented two different broods, one in April and 
one in May. 
P. shumardi spawned during April and May. Young 
collected on June 29, 1966, ranged in size from 36 to 
43 mm in total length. 
Annual gonadal changes were fairly similar in all 
TABLE 4. Comparison of the number of young and adult 
Percina at the Sullivan and Eagle Creek stations. Fish are 
from the 1965 and 1966 collections made with rotenone. 
1965 1966 
Young Adult Young Adult 
Sullivan 
P. maculata 55) 46 28 5 
P. phoxocephala 4 39 15 28 
P. caprodes 4 19 ] 6 
Eagle Creek 
P. maculata 38 15 0 5 
P. phoxocephala 3 5 56 12 
P. caprodes 3 6 2 3 
of these darters. During the summer and early fall, 
the gonads were usually reduced in size. By October, 
the gonads began to increase in size, and body coloration 
became intensified. The gonads reached maximum de- 
velopment in spring when water temperature, water 
levels, and possibly photoperiod helped determine the 
time of spawning. 
There is very little sexual dimorphism in the four 
species of Percina. Petravicz (1938) found that the 
ventral fins of male P. maculata were a little broader 
than those of the females. P. shumardi showed the 
greatest sexual dimorphism, the males having much 
longer anal fins. 
FOOD HABITS 
Stomach analyses were made on 93 P. maculata 
103 P. phoxocephala, 36 P. caprodes, and 42 P. shu 
mardi. A list of all the food organisms found and identi 
fied in stomachs is given in Table 5. 
Food habits of both young and adult P. maculati 
at Sullivan were compared from spring (March—May) 
summer (June-August), fall (September—November) 
and winter (December—February) collections (Table 6) 
The greatest variety of organisms was eaten in th 
summer. Dipteran larvae and pupae (particular! 
chironomidae) were an important part of the die 
during all seasons. Simulid larvae predominated 1 
the spring and fall. Crustaceans were found in stomach 
only during the summer and winter. Baetids made w 
the greatest volume of food in the summer. 
Feeding intensity was heaviest in the spring. Stomac 
contents from three adult P. maculata collected on Apr 
18, 1966, weighed 132 mg, 113 mg, and 112 mg, an 
were indicative of the generally full stomachs foun 
at this time. Summer stomach contents usually weighe 
no more than 50 mg and in most cases less than 10 m 
Much or all of this difference in volume of food frot 
spring and summer stomachs may be due to increase 
digestion rates in the summer. 
Young P. maculata showed a rapid change in foo 
habits from a diet predominantly of microcrustaceal 
to one comprised mainly of insect larvae. Eight yount 
of-the-year, ranging in size from 18 to 24 mm, ©0 
lected on June 8, 1965, were already eating chironom! 
larvae and ephemerid nymphs, although Copepoda an 
Cladocera still predominated in the diet. The gener 
difference in food habits between young-of-the-ye: 
and adults during the summer was a greater utilizatic 
of microcrustaceans and small insect larvae in yout 
to greater utilization (particularly by volume) of Eph 
meroptera nymphs and Trichoptera larvae in adult 
Turner (1921) found no change in food habits | 
P. maculata that ranged in size from 34 to 57 mm. 
Food habits of P. maculata at Vandalia and Carl) 
were very similar to those in the Sullivan area, wi 
baetid nymphs, chironomid, simuliid, and hydropsych 
larvae predominating (Table 7). 
