7222

• UCREFRP Catalog Number: 7222
• Author: Marsh, P. C. and J. E. Brooks
• Title: Predation by Ictalurid Catfishes as a Deterrent to Re-Establishment of Hatchery-Reared Razorback Suckers
• USFW Year: 1989
• USFW - Doc Type: The Southwestern Naturalist
• Copyright Material: YES

June 1989 Marsh and Brooks-Ictalurid predation on Xyrauchen 191
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,+

TABLE 2-Food habits of channel catfish >150 mm standard length (SL) and flathead catfish >100
mm SL from the Gila River near Clifton, Arizona, 13 to 15 September 1985. Approximately 25,875
razorback suckers were introduced 13 September 1985 at the upstream margin of the study area. Data
are number of stomachs containing a given food item (n), percentage frequency of an item among fish
containing food (%), mean (±SD) number of individual items per stomach (No.), and mean (±SD)
percentage biomass of items among stomachs containing that item (% B).
Channel catfish (35 stomachs; 6 empty) Flathead catfish (38 stomachs; 4 empty)
Food item n % No. % B n % No. % B
Fish
Xyrauchen texanus 16 55.2 3.8 ± 3.7 84.9 ± 24.7 27 90.0 2.2 ± 1.4 95.3 ± 14.2
Notropis lutrensas 5 17.2 1.0 ± 0.0 54.4 ± 38.8 0
Undetermined fishes 3 10.3 1.0 ± 0.0 26.3 ± 26.1 3 10.0 1.0 ± 0.0 12.3 ± 9.3
Aquatic insects
Ephemeroptera 5 17.2 2.2 ± 1.6 6.8 ± 5.1 1 3.3 60.0 100.0
Odonata 1 3.4 1.0 1.0 0
Hemiptera 1 3.4 1.0 40.0
Megaloptera 6 20.7 2.2 ± 1.5 30.2 ± 26.8 1 3.3 1.0 5
Trichoptera 6 20.7 2.8 ± 1.7 16.8 ± 22.1 0
Coleoptera 4 13.8 12 ± 2.0 5.8 ± 6.4 0
Diptera 4 13.8 3.8 ± 3.4 8.5 ± 5.8 0
Undetermined taxa 2 6.9 1.0 ± 0.0 3.0 ± 2.8 0
Terrestrial inverte-
brates 1 3.4 1.0 1.0 0
Plant material 6 20.7 31.2 ± 36.8 1 3.3 1.0 <I
Algae 9 31.0 6.8 ± 6.5 0
Detritus 7 24.1 51.7 ± 44.5 1 3.3 45.0
Inorganic matter 1 3.4 8.0 6 20.0 2.0+ 0.0
collected after the 1984 stocking suggested that catfish predation might have
significantly reduced numbers of newly-planted razorback suckers (Table 1).
Predation was even higher in 1985, when 55% of channel catfish and 90% of
flathead catfish contained razorback suckers (Tables 1 and 2).
In January 1986, four of five flathead catfish had eaten razorback suckers,
while no razorback sucker remains were present among stomach contents of 10
channel catfish, most of which were empty (Table 1). Thus, although the winter
sample size was small, predation by flathead catfish appeared similar to that
observed during autumn studies, but total catfish predation on stocked razorback
suckers was less because channel catfish feeding was negligible. We attribute
reduced feeding by channel catfish in part to colder winter water temperatures
that generally lowered activity of the animal; the more piscivorous flathead
catfish apparently were less lethargic when presented with vulnerable prey.
There was a positive correlation (r2 = 0.76, P < 0.10) between predator size
and length of razorback suckers ingested in 1985 (Fig. 1); similar relationships
have been reported for other predator-prey species pairs (Mauck and Coble,
1971; Shireman et at., 1978; Timmons et al., 1980). Mean size of razorback
suckers consumed by flathead catfish was significantly (ANOVA, F-test, P >