8022

• UCREFRP Catalog Number: 8022
• Author: Muth, R. T., et al.
• Title: Reproduction and Early Life History of Razorback Sucker in the Green River, Utah and Colorado, 1992-1996.
• USFW Year: 1998.
• USFW - Doc Type: 34,
• Copyright Material: NO

bluehead suckers, 79% were tlannelmouth suckers, 11 % were razorback suckers, and 1 % were
unidentified specimens. About 25% of all nonnative cyprinids caught in either the middle or
lower Green River were classified as unidentified, and over 99% of those were likely red shiners,
sand shiners, or fathead minnows that were too small (less than 6 mm TL) to distinguish with
confidence based on existing morphological criteria.
Other taxa collected inconsistently or in low numbers from both river sections were
native chubs Gila sp., Colorado squawfish, and speckled dace Rhinichthys osculus, and
nonnative common carp Cyprinus carpio, redside shiner Richardsonius balteatus, white sucker
Catostomus commersoni, and green sunfish Lepomis cyanellus, Native mottled sculpins Cottus
bairdi, and nonnative northern pike Esox lucius and brook sticklebacks Culaea inconstans (a
recent addition to the known fish fauna of the middle Green River drainage, Utah; Modde and
Haines 1996) were caught only in the middle Green River, whereas nonnative black bullheads
Ameiurus melas and channel catfish Ictalurus punctatus were unique to collections from the
lower Green River.
Of the 16 species caught in the middle Green River, 10 were recorded from drift-net,
seine, and light-trap collections; one (mottled sculpin) was represented in seine and light-trap
collections; one (northern pike) was only found in seine collections; and four (Colorado
squawfish, redside shiner, brook stickleback, and green sunfish) were only captured by light
traps. In the lower Green River, 11 of the 15 species collected were represented in seine and
light-trap collections, and the other four species (white sucker, black bullhead, channel catfish,
and green sunfish) were exclusive to seine collections, Seine and light-trap collections from the
lower Green River in each year were composed primarily of nonnative cyprinids, and percentages
contributed by those fishes to the total annual catch of each gear ranged from 66 (1994) to 99%
(1993) for seines and from 77 (1993) to 98% (1995) for light traps. Most fish collected by drift
nets or seines from the middle Green River were either bluehead or tlannelmouth suckers. For
light-trap collections from the middle Green River, nonnative cyprinids dominated the total catch
in 1993 (88%) and 1995 (70%), whereas native catostomids predominated in 1994 (97%) and
1996 (63%). Seines were effective in capturing a wide range offish sizes (less than 10 to over
200 mm TL), whereas most fish collected by drift nets and light traps were less than

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