7990

• UCREFRP Catalog Number: 7990
• Author: Tyus, H. M.
• Title: Razorback Sucker ‎(
• USFW Year: 1997.
• Copyright Material: NO

jweniles from backwaters in the Colorado River near Moab. Smith (1959) caught two
young fish on the Colorado River in Glen Canyon, one from a backwater and one from
a creek mouth. Gutermuth et al. (1994) captured two small juvenile razorback suckers
in a silty backwater in the lower Green River in 1991. Juveniles also have been
collected in the middle Green River. Two juveniles (59 and 29 mm) were collected in a
main channel backwater in 1993 and 28 jweniles (74-124 mm) were collected from Old
Charley Wash, a wetland adjacent to the Green River, in October 1995 (Modde 1996).
Another 45 'uvenile n~zorback suckers wer
1 e collected from Old. Charley Wash m
August 1996 (T. Modde, USFWS, pers. comm., 1996).
r
For nursery habitat, young razorback suckers presumably require quiet, warm, shallow
water (e.g., eddies and backwaters) in riverine environments. Backwaters provide 1
quiet, wane water where there is a potential for increased food availability. During
higher flows, flooded bottomlands and tributary mouths may provide still water. Tyus
and Karp (1989, 1990) identified the importance of flooded bottomlands for the growth
of young fish. Many of these off-channel habitats have been eliminated in the Colorado
River basin by construction of mainstem dams, diking of floodlands, and channelization
(Boland 1953, Tyus and Karp 1989, Osmundson and Kaedin 1990. Gravel- i n
g ) p t po ds
connected to the river may provide a substitute for inundated riparian cottonwood
bottomlands, other wetlands, and oxbow channels. However, these habitats also
support nonnative predatory fish, such as largemouth bass, catfish, and green sunfish,
which feed on young razorback suckers (Minckley et al. 1991, Mueller 1995). In
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