7304

• UCREFRP Catalog Number: 7304
• Author: Tyus, H. M.
• Title: Distribution, Reproduction, and Habitat Use of the Razorback Sucker in the Green River, Utah, 1979-1986
• USFW Year: 1987
• USFW - Doc Type: Transactions of the American Fisheries Society
• Copyright Material: YES

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RAZORBACK SUCKER BIOLOGY IN UTAH

115

TABLE 2. -Characteristics of habitat occupied by radio-tagged razorback suckers, Green River basin, 1980 and
1985. N = number of observations; where only one was made, the "average" value is that observation.

Range

Average

Depth (m)

Velocity (m/s)
Range

Substrate"

Average N
1980
1.3 I
1.4 4
1.4 I
1.7 I
1.6 I
1.5
1985
1.3 3
\.0 5
1.8 3
0.9 5
\.2 I
1.8 I
1.3

0.6-2.1
I.l-1.7
0.9-2.4

0.6-2.3
0.9-2.1
0.8-3.4
0.6-1.7

0.2
0.1 S, Si
0.5 S
0.2 S
0.4 Si
0.3
0.2 S
0.3 S
0.3 S, Si
0.5 S
0.4 R
0.7 S
0.4

0.1-0.2

0.1--0.5
0.0--0.5
0.1--0.5
0.4--0.6

" S = sand, Si = silt, R = rubble.

the Green River before contact with it was lost on
August 13. Similar movements were observed for
five razorback suckers tracked less rigorously in
1985.
The apparent lack of spawning migrations in
fish radio tracked in 1985 coincided with an ab-
sence of ripe fish in the 1985 collections; perhaps
these fish did not spawn. None were tuberculate
or ripe when tagged (May 9-20), and one was still
not ripe when it was recaptured 1 week after re-
lease.

,
,

Habitat

Most ripe razorback suckers in the mains tern
Green River were collected over coarse sand sub-
strate, but some were collected near gravel and
cobble bars. Water temperatures where these ripe
fish were captured in 1984 ranged from 10.5 (May
10) to 18"C (June 14), averaging about 150C (160C
for ripe females). In the Duchesne River in 1984,
ripe females were taken at 150C. In 1986, ripe fish
in the Green River were collected May 13-28 at
water temperatures of 11.5-180C (average 15.50C,
including females). An additional four ripe fe-
males were captured in warm (17-190C) flooded
bottomlands adjacent to the river channel from
May 18 to May 28, 1986. Substrate in these bot-
toms was variable, ranging from flooded vegeta-
tion to sand and silt.
Razorback suckers appear to stage and spawn
in different habitats. Large concentrations at the
junction of the Green River and Ashley Creek
prompted many collecting trips up Ashley Creek

..

in search of spawning areas. However, no evi-
dence of spawning was discovered there and no
razorback suckers were captured more than 0.5
km upstream in the creek. The habitat does not
appear to be suitable for spawning because the
substrate is silty. Possibly, the large shallow eddy
produced by the creek and the drainage ditch to
Stewart Lake at this location make the area desir-
able for staging. Fish tagged in this eddy in early
May were recaptured both upstream and down-
stream in spawning condition, which tends to sup-
port this hypothesis.
Habitat use outside the breeding season was de-
termined by radiotelemetry, because high water
turbidity made direct observations impossible. Of
10 razorback suckers implanted with radio trans-
mitters, one implanted in 1981 died, and two oth-
ers implanted in 1981 and one in 1985 were lost
before information was obtained. The remaining
six fish lived in similar habitats (Table 2), and
there was little difference between mean monthly
water depths and velocities occupied by the one
fish in 1980 (1.5 m and 0.3 m/s) and the five fish
in 1985 (1.3 m and 0.4 m/s). The fish lived pre-
dominately in the main channel of the Green and
Duchesne rivers, in depths ranging from 0.6 to 3.4
m, and were most common in fUns near shore in
the spring and on midchannel sand bars in sum-
mer. The preference for midchannel sand bars in-
stead of deeper pools during the summer was sur-
prising, but all of the radio-tagged fish moved into
these areas in July. These bars were composed of
unconsolidated coarse sand, with surficial dips and
ridges. Water depths on these bars were usually