12 
areas were not well defined. However, certain males 
did select stations at which they remained, except to 
feed, and they were perpetually antagonistic toward any 
other males that approached their stations. No ag- 
gressiveness by males toward females or between 
females was noted. 
DIET AND FEEDING HABITS 
In 108 specimens of P. sciera examined for stomach 
contents, only current-dwelling insect immatures were 
found. The number of individual food items was often 
quite high, with as many as 116 and an average of 12.5 
items per fish, but the variety of organisms was con- | 
sistently low. During the entire study only midge 
larvae and pupae; larvae of caddisflies, black flies, and 
snipe flies; and naiads of mayflies and stoneflies were 
encountered in the stomach contents (Table 3). The 
principal food items were midge and black fly larvae, 
although some seasonal variation in the diet occurred 
(Fig. 9). Caddisfly larvae formed a large portion of 
the diet during the summer, and the dipterans and 
mayflies were the main components during other 
seasons. The variation was probably correlated with 
the relative availability of the different insect larvae 
throughout the year. 
TapLE 3.—Stomach contents of Percina sciera of all ages collected from the Embarras River between August 4, 1967 and June 8, 1969. 
Figures in parentheses are numbers of stomachs examined. 
Percent Occurrence of Food Organisms in Stomachs Examined 
Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. 
Food Organism (10) (8) (6) (10) (10) (6) (13) (16) (16) (11) (2) 
Midge larvae, pupae 10.0 100.0 83.3 20.0 40.0 50.0 87.5 27.3 
Black fly larvae 70.0 37.9 83.3 80.0 50.0 Bone 61252 8 /e 0 Tee 9.1 
Caddisfly larvae 10.0 er Oh 10.0 20.0 83.3 15.4 25.0 BH td) 9.1 
Mayfly naiads 10.0 3000 40.0 70.0 66.7 15.4 75.0 50.0 18.2 
Snipe fly larvae wee rate Sipe ee Aone IOs2 ere Beer che 6.3 se 
Stonefly naiads 12.5 ae ee ae 
Mean Number of Food Organisms Per Stomach 
Feb. Mar Apr May June July Aug. Sept. Oct. Nov. Dee. 
Midge larvae, pupae 0.4 8.9 2.5 1.0 1.4 2.2 7.9 se) 
Black fly larvae 1.4 1.4 10.3 29.6 4.0 0.3 eS Sel Ones 13 0.2 
Caddisfly larvae Om ee ee 0.1 0.3 16.2 0.2 2.2 iL 4 0.2 
Mayfly naiads (O), 11 0.3 1.9 Deo 1.8 0.8 4.9 ies! 0.2 
Snipe fly larvae A iieus ee ire aay 0.2 Boi Re. (0). HL aes 
Stonefly naiads 0.1 Sok: Re. 
® Midge and Black fly larvae not separated in August and September. 
100 
») 
Sessa cw 
90 
my 
. 
80 
70 
60 
50 
40 
PERCENT OF FOOD ITEMS 
30 
20 
FEBRUARY 
MARCH 
APRIL 
MAY 
JUNE 
JULY 
AUGUST 
Fig. 9. — Seasonal variation in 
the diet of Percina sciera of all 
sizes. Percent of food item refers 
to total contribution in all fish 
examined each month. 
SEPTEMBER 
OCTOBER 
NOVEMBER 
