8104

• UCREFRP Catalog Number: 8104
• Author: Modde, T. and D. B. Irving
• Title: Use of Multiple Spawning Sites and Seasonal Movement by Razorback Suckers in the Middle Green River, Utah
• USFW Year: 1998
• USFW - Doc Type: North American Journal of Fisheries Management
• Copyright Material: YES

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RAZORBACK SUCKER SPAWNING
to the Escalante spawning location in 1994. The
fish collected in Island Park in 1993 also moved
to the Escalante spawning area during 1994. Two
(224B6B and 177D1B) of the remaining four fish
were located at the Escalante spawning area, while
the remaining two fish (181765 and 180446) were
not located at an identified spawning site in the
spring of 1994. In 1995, all six adult males im-
planted with transmitters were located at the Es-
calante spawning site. In addition, two fish
(224B6B and 181765) also traveled to Che Yampa
River spawning site during the high-flow spawning
period.
Movement of fish to the Escalante spawning
area (RK 492-501) was associated with increases
in discharge and, to a lesser extent, water tem-
perature. In 1994, fish were not observed on the
spawning bar when daily temperature first in-
creased to 16°C. However, as flows increased rap-
idly, fish were observed on the bar despite the
reduction in temperature (Figure 3). Three fish
were found at the Escalante spawning bar in 1994
coincident with peak flows and daily maximum
temperatures exceeding 14°C. In 1995, five trans-
mitter-implanted razorback suckers were found at
the Escalante spawning area coincident with a rap-
id increase in discharge (approximating the mag-
nitude observed during the previous year) on the
ascending limb of the hydrograph. Given this ini-
tial response to flow, two individuals remained at
the spawning area during the peak-flow period of
late May and early June 1995.
Movement Patterns Based on Capture Data
Razorback sucker capture data during the spring
period between April 1 and June 30 consisted of
657 observations of 433 fish. All razorback suck-
ers were collected between RK 88 and 555, with
only nine fish being captured downstream of RK
389. A pattern of movement was evident during
the spring months. Thirty-nine percent of all fish
collected were taken between RK 499 and 507, the
most frequently used reach of the Escalante spawn-
ing area. Only 4.7% of the fish were collected at
another spawning site in the lower Yampa River
(RK 555-561), and still fewer (1%) in the vicinity
of Island Park (RK 523-539; Figure 3). Some fish
were found between the mouth of the Duchesne
River (RK 399) and the outlet to Old Charley Wash
(RK 401.5) in each 2-week interval between April
and Tune. Following spawning (late May and
June), most fish were captured downstream of the
Escalante spawning area (RK 500). Many post-
spawned fish were captured at the mouths of trib-
utaries including Ashley Creek (RK 481), Stewart
Lake (RK 480), Old Charley Wash (RK 401.5),
and the Duchesne River (RK 399).
Among the 433 razorback suckers collected
through April and June between 1975 and 1992,
62 were recaptured at Escalante spawning area.
Fifty-one fish were captured twice at the area and
11 were captured three different years. Only a sin-
gle individual was captured in two different years
on the Yampa River site and two individuals were
captured at different years on both the Escalante
and Yampa River areas. One fish, not included in
the above summary was captured at both the Es-
calante and Yampa River areas in the same year.
Discussion
Both radiotelemetry and electrofishing data in-
dicated that many razorback suckers tend to move
downstream after spawning and many move to the
vicinity of the wetland complex near Ouray, Utah,
and the mouth of the Duchesne River. Fish typi-
cally move upstream to spawning areas and then
back downstream following spawning (e.g., Alt
1977; Welcomme 1985). The significance of the
long-range movements observed before fish
spawned is unclear, but downstream movement in
general appears only during the high-flow season.
Downstream movements of razorback sucker fol-
lowing spawning may be associated with foraging
behavior (Tyus and Karp 1990). Razorback sucker
adults may be attracted to wetland outlets and trib-
utary mouths due to preferred temperature ranges
(Bulkiey and Pimentel 1983) or higher productiv-
ity (Mabey 1993). During the late summer of 1995,
eight adult razorback suckers were collected in a
wetland on the Ouray National Wildlife Refuge
(Modde 1996). Fish presumably accessed the wet-
land during the peak spring flows, when the wet-
land was connected to the river, and remained in
the wetland after river elevation lowered. Follow-
ing the spring high-flow period, razorback suckers
monitored with radio transmitters returned up-
stream to the vicinity of Split Mountain Canyon.
These fish appeared to remain in the canyon during
both winters of study.
Tyus and Karp (1990) suggested that both flows
and temperature influenced the onset of move-
ments to spawning locations. Telemetry data of
adult male razorback suckers in this study corrob-
orated their observations and indicated that dis-
charge appeared as the most consistent cue for
movement to the primary spawning location. In-
crease in discharge has been reported to initiate
movement of other catostomids to spawning areas.
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