9489

• UCREFRP Catalog Number: 9489
• Author: Mueller, G.
• Title: The Role of Stocking in the Reestablishment and Augmentation of Native Fish in the Lower Colorado river Mainstream ‎(1998-2002)‎.
• USFW Year: 1998-2
• USFW - Doc Type: 03-288,
• Copyright Material: NO

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Table 1.1. Sample composition (%) of fish collected in the Colorado River between Davis Dam ~d Lake
Havasu from October 1999 to May 2002.

Species 1999 2000 2001 2002 Average
Common carp 11.8 21.9 21.0 20.4 18.8
Flannelmouth sucker 22.5 17.4 17.2 17.6 18.6
Largemouth bass 23.8 11.5 11.7 18.5 16.4
Bluegill 20.8 10.1 7.5 15.4 13.5
Threadfin shad 1.7 17.4 13.7 0.5 8.3
Redear sunfish 2.4 5.9 11.4 10.2 7.4
Yellow bullhead 3.6 3.0 5.0 2.9 3.6
Channel catfish 3.2 4.7 3.4 3.0 3.6
Razorback sucker 1.9 2.5 2.6 4.7 2.9
Striped bass 1.9 1.8 2.2 1.8 1.9
Green sunfish 3.7 1.9 1.2 2.8 2.4
Black crappie 2.2 0.7 0.8 0.7 1.1
Rainbow trout 0.5 0.4 1.2 0.7 0.7
Goldfish 0.0 0.4 0.5 0.6 0.4
Smallmouth bass 0.2 0.3 0.7 0.3 0.4
Black bullhead 0.0 0.4 0.0 0.0 0.1
RZB/FMS hybrid 0.0 0.1 0.0 0.0 <0.1
Bonytail 0.0 0.0 0.0 0.1 <0.1
Redshiner present but not counted

Common carp (18.8%) was the most prevalent species captured, followed by largemouth bass (16.4%),
flannelmouth sucker (18.6%), bluegill (13.5%), threadfin shad (8.3%), redear sunfish (7.4%), and others
(17.0%) (Table 1.1). Species composition was relatively stable over the 4-year period.
Normally, fish lengths were recorded, however weights were not always taken. We often experienced
problems with digital scales and felt it unnecessary to measure the more numerous species (threadfin shad and
common carp). A summary offish numbers, average lengths, weights, and ranges is shown in the appendix.
We sampled river wide in 2000 but captured and saw few fish in the main stem channel. Netting suggested
that fish were concentrated in the slack or backwater areas. There were distinctive seasonal shifts in fish
distribution. Fish appeared to concentrate in backwaters during the winter. While we continued to sample
some channel areas, the majority of netting in 2001 and 2002 centered in backwater areas where fish were
more abundant and more easily captured.

Visual Surveys

Twenty-five (15 minute) surveys were completed between Davis Dam and Lake Havasu. We observed
2,172 fish during the 6.25-hour effort (Table 1.2). Eight species or groups offish could be easily identified.
Common carp was the most numerous (56.3%), followed by striped bass (23.8%); flannelmouth sucker
(13.4%); channel catfish (3.5%); black bass (smallmouth and largemouth bass) (2.1%); razorback sucker
(0.1 %); and sunfish (0.1 %). Flannelmouth sucker and young striped bass were generally found in large (>50)
schools.

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