9499

• UCREFRP Catalog Number: 9499
• Author: Osmundson, D. B.
• Title: Removal of Non-native Centrarchids from Upper Colorado River Backwaters, 1999-2001
• USFW Year: 2003.
• USFW - Doc Type: Summary of Results.
• Copyright Material: NO

Table 1. Total number of nonnative fish removed from backwaters in the upper Colorado
River, 1999-2001.

Species 1999
Spring 1999
Fall 2000
Spring 2000
Fall 2001
Spring 2001
Fall
Total
Black bullhead 124 756 881 367 579 844 3,551
Black crappie 4 3 1 6 3 10 27
Bluegill 2 128 92 104 103 201 630
Channel catfish 13 0 20 42 13 13 101
Common carp 548 710 1,354 1,765 646 1,619 6,642
Green sunfish 1,563 1,516 2,226 1,883 1,561 1,683 10,432
Largemouth bass 85 504 172 1,645 439 913 3,758
Smallmouth bass 1 3 14 3 6 0 27
White sucker 279 329 416 386 661 736 2,807
Northern pike 0 1 0 0 1 0 2
Total 2,619 3,950 5,176 6,201 4,012 6,019 27,977
the seasonal efforts, and 14 in one of the efforts (fall 1999). Backwater habitats were much
more common in the Grand Valley (upstream of rm 152) than in the Loma-to-Westwater
reach.
Largemouth bass
Largemouth bass were abundant and widespread: on average, 45% of the backwaters
(13-90% range; N = 6 periods) electrofished by boat and 70% of those electrofished by barge
(28-100% range) yielded largemouth bass. Distribution was fairly even throughout backwaters
of the Grand Valley. One two-mile reach upstream of Loma (rm 154-156) contained two
backwaters, each of which had a high density of largemouth bass (Fig. 2). In Ruby and
Horsethief canyons downstream of Loma, only three backwaters (two between rm 146 and
8