9341

• UCREFRP Catalog Number: 9341
• Author: Modde, T., R. T. Muth and B. G. Haines
• Title: Floodplain Wetland Suitability, Access, and Potential Use by Juvenile Razorback Suckers in the Middle Green River, Utah
• USFW Year: 2001
• USFW - Doc Type: Transactions of the American Fisheries Society
• Copyright Material: YES

19vb
1099
Wetland
River (Jensen)
10 20 30 10 20 30 10
Dissolved Oxygen 1996
- surface
- Bottom
10 20 30 10 20 30 10
may Jun Jul ^uy wN may oulI V..
FIGURE 2.-Comparison of temperature, dissolved oxygen, and depth in the Green River (Jensen, Utah) and the
Old Charley Wash wetland during the spring and summer of 1995 and 1996.
3
SUCKER WETLAND USE
U
0
J
2.7
rn
M
0.9
0
1995
--- Wetland
River (Jensen)
Dissolved Oxygen 1995
1 1,5 1 1,5 1 1,5 1 1,5 1 15
5 1 1
Adult fish accessing the wetland from the Green
River dominated the biomass of fish collected after
draining Old Charley Wash, making up 80% and
77% of the biomass in 1995 and 1996, respec-
tively. Fathead minnow and red shiners were in-
cluded in the category of fish produced in the wet-
land, although many probably accessed the wet-
land from the river. Although age-0 fish were only
a small fraction of the total biomass collected dur-
ing draining, they composed the numerical ma-
jority of fish collected.
The age-0 razorback sucker was the most abun-
dant native fish collected in Old Charley Wash
during both 1995 and 1996. The 28 fish collected
in 1995 averaged 94 mm (range, 74-125 mm) in
total length and 9.5 g (range, 3-18 g) in weight.
In 1996, another 45 razorback suckers were col-
30
24
18
12
6
0
12
10
8
6
4
2
0
30
24
18
12
6
0
12
10
8
6
4
2
0
2.
1.
0.
lected; these fish averaged 65.9 mm (range, 44-
83 mm) in total length and 3.8 g (range, 1-6 g)
in weight. In 1995, two razorback sucker adults
were collected; none were collected in 1996. Other
native fishes collected in 1995 and 1996 included
the juvenile Colorado pikeminnow, flannelmouth
sucker, and roundtail chub.
Discussion
When razorback sucker larvae in the Green Riv-
er emerge during peak discharges in the spring
(Tyus 1987), off-channel floodplain wetlands like
Old Charley Wash represent a velocity refuge and
thermal optimum. During high-volume spring
flows, temperatures in the main channel are re-
duced by the effect of snowmelt runoff. Main-
channel habitats offer little refuge to larval fishes