7129 ‎(2)‎

• UCREFRP Catalog Number: 7129
• Author: Barham, W. T., H. J. Schoonbee and J. G. J. Visser
• Title: Use of Electronarcosis as Anesthetic in the Cichlid,
• USFW Year: 1989
• Copyright Material: YES

22 JOURNAL OF THE ARIZONA-NEVADA ACADEMY OF SCIENCE VOL. 16
Table 1. Mean number (N) and biomass (B) of food items in channel catfish from the Coachella Canal, California.

Food Item

N
A
B

N STATION
B
B N
C
B
A + B + C
N B
Insects
Baetis sp. 0.15 <0.01 0.40 <0.01 0.43 <0.01 0.18 <0.01
Odonata 5.26 0.16 0.00 0.00 0.48 <0.01 4.42 0.13
Smicridea utico 135.20 0.54 1.58 0.05 135.90 0.45 135.30 0.51
Nectopsyche sp. 4.28 <0.01 0.20 <0.01 0.14 <0.01 3.56 <0.01
Parargyractis confusalis 2.81 0.01 0.20 <0.01 0.62 <0.01 2.42 0.01
Chironomidae 9.77 <0.01 0.20 <0.01 0.38 <0.01 8.14 <0.01
Crayfish 0.06 0.008 0.00 0.00 0.00 0.00 0.05 0.007
Fish 0.02 0.03 0.00 0.00 0.00 0.00 0.00 0.00
Filamentous algae - 0.15 0.00 0.00 0.00 0.00 - 0.13
Miscellaneous 0.04 0.01 0.00 0.00 0.38 <0.01 0.09 0.01
Unidentified 0.008 0.01 0.00 0.00 0.00 0.00 0.006 <0.01
Number of fish 125 5 21 151
Mean TL (mm) 168 105 129 161
Mean weight (gm) 52.79 13.20 18.16 46.66
Biomass per stomach (gm) 1.16 0.06 0.46 0.82

W y,
(7 U
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H W
Z Z)
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W W
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00
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MOWZn.QQu-QO
Figure 1. Mean percentage frequency and wet weight
biomass of food items in channel catfish
stomachs (N = 151) from the Coachella
Canal, California.
99% frequency (Fig. 1), averaged 131 individuals per stoma
(Table 1), and contributed 62.2% of overall biomass (Fig.
One catfish (323 mm TL) contained 646 individu? ;
Frequency of occurrence of the caddisfly was similar for
size classes of fish (Fig. 3); however, at Station A tr
percentage contribution to biomass dropped from 80-925:
fish of 150-199 mm TL to 55-28% in fish of 200-299 mm
Mean individual weight of caddisflies was constant at 3-5
The total of approximately 20,000 caddisflies observe
stomachs included only 13 pupae and no adults.
Chironomid midges (including larvae and a few pupae
adults) were in more than 70% of all stomachs, but due to
small size and low numbers contributed only a fraction :.
percentage of biomass. Occurrence was nearly 80% at St,:
A but only 33 and 20% at Stations B and C, respecti'r
Based on the sample from Station A, utilization was gre,-
by smaller catfish; 75-98% by fish of 150-199 mm
compared to about 507c by fish of 200-299 mm TL. A'
individual weights of chironomids were 1-3 mg.
Nearly all odonate larvae were damselflies of the ge:•
Hetaerina, although a very few gomphidae (dragonflies) w-
encountered. Overall occurrence was about 64% but diffe-
among sites: 75%, 0%, and 33% at Stations A, B, am.
respectively. Odonate contribution to total biomass
nearly 16%, due largely, to their importance at Statio-;
Utilization of these relatively large insects (mean indivi4
weights of 10-46 mg) was 100% by fish of 200-299 mm TL
only 13% by fish of <100 mm TL; the relation between
size and occurrence was approximately linear between tt:
extremes (Fig. 3). Larger fish ate the largest odonates; nr .
individual weights of 10, 12, 38, and 46 mg were consume,; =_-
fish of mean lengths of 121, 169, 269, and 338
respectively. These were the only insects which ci,1'--"_?
showed this relationship.
ISf
Fi
in
bi
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fig
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al
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sI
B
m