7856

• UCREFRP Catalog Number: 7856
• Author: Muth, R. T. and D. E. Snyder
• Title: Diets of Young Colorado Squawfish and Other Small Fish in Backwaters of the Green River, Colorado and Utah
• USFW Year: 1995
• USFW - Doc Type: The Great Basin Naturalist
• Copyright Material: YES

98 GREAT BASIN NATURALIST [Volume 55
TABLE 1. Diets by total-length intervals (mm) of nine fish species collected during summer and autumn 1987 from
sure is mean percentage contributed by each food category to total volume of food in each digestive tract (mean of vol-

Food category

11-20
Red shiner
21-30 31110

>40
Sand shiner
21-30 31110

>40
Fathead minnow
11-20 21-30 31-40

>40 Colorado
squawfish
<11 11-20
------- ------------------------------------ Upperreacha ---------------------------- ----- -----------
Insects
Unidentifiable parts 11 9 25 37 3 9 22 2 1 1
Semiaquatic or terrestrial 1 4 6 12 5 <1
Dipteraimmatures 30 27 29 13 25 19 3 7 4 4 13 70 r
Chironomidae adults 1 3 3 10 9 4 9
Anisoptera nymphs
Aquatic Coleoptera 3 10
Corixidae <1 1 10
Trichoptera larvae 1 1 1 1
Ephemeroptera nymphs 1 2
Zooplankton
Cladocera and Copepoda 7 6 3 3 <1 <1 26 16
Rotifera 6 <1 <1 <1 <1 16 1
Ostracoda 1 1
Gammaridae <1
Hydracarina 2 <1
Invertebrate eggs 1 1 <1 1 <1 <1 3 1
Nematoda <1 1 6 1
Fish
Plant seeds 7 9 <1 <1 1 1 4 <1
Algae 2 4 1 1 2 2 2 2 2
Organic-inorganic debris 35 32 22 26 50 60 64 87 93 90 31 10
Number offish 45 140 63 17 40 19 7 0 108 75 26 40 305
Mean % fullness of
digestive tracts 52 64 44 38 81 77 73 83 84 75 40 59
-------------------------------------------- Lowerreacha ------------------------------ -------------
Insects
Unidentifiable parts 3 13 16 23 12 14 6 2 2 1
Semiaquatic or terrestrial 9 8 10 11 2 <1
Dipteraimmatures 55 36 32 28 37 31 27 9 9 4 <1 19 47
Chironomidae adults 1 3 5 2
Aquatic Coleoptera 2 1 3 6
Corixidae <1
Trichoptera larvae 1 1 1 6 <1
Ephemeroptera nymphs <1 1
Anisoptera nymphs
Zooplankton
Cladocera and Copepoda 6 5 3 <1 1 1 <1 <1 29 35
Rotifera <1 <1 <1 7 3
Ostracoda <1 <1 <1 2 <1
Gammaridae
Hydracarina
Invertebrate eggs <1 1 <1 3 5 2
Nematoda 1 <1 9 18 1 1 1
Fish
Plant seeds 9 7 4 5 <1 2
Algae 1 1 1 1 2 <1 1 1 2 3 <1
Organic-inorganic debris 18 23 26 28 40 32 59 88 87 93 95 33 10
Number offish 62 208 138 56 10 10 6 9 31 49 32 27 301
Mean % fullness of
digestive tracts 58 60 49 36 66 52 37 72 85 80 78 45 70
allpper reach = confluence of Green and Yampa rivers at RK 555 (river kilometers above confluence of the Green and Colorado riven) in Echo Park, Dinosaur National
Monument, CO, to Sand Wash, UT (RK 346); lower reach = Sand Wash to Turks Head, Canyonlands National Park, UT (RK 35).