9678

• UCREFRP Catalog Number: 9678
• Author: Tyus, H. M. and C. A. Karp.
• Title: Habitat Use and Streamflow Needs of Rare and Endangered Fishes
• USFW Year: 1990.
• USFW - Doc Type: Flaming Gorge Studies - Draft Consolidated Report Preliminary.
• Copyright Material: NO

has been imp]icated in the decline of the bonytail chub in that system, fish
collections in DNM before and after the poisoning (Binns et al. 1963; Vanicek
and Kramer 1969; Vanicek et al. 1970) suggested that the downstream extent of
the poison was not a factor in the almost total extirpation of the species
from the Echo Park area. Flaming Gorge Dam operations could affect the future
of bonytail chub re-introductions in the Green River system and needs to be
considered in reintroduction efforts.
Razorback Sucker
Adult razorback suckers have been captured in flat-water sections of the
upper Green River (km 282 - 552), and in the lower 21 km of-the Yampa River
(Azevedo 1962; Vanicek et al. 1970; Hoiden and Stalnaker 1975; Seethaler et
al. 1979; McAda and Wydowski 1980; Miller et al. 1982a; Tyus et al. 1982b;
Tyus 1987; Tyus and .Karp, in review). Adult fish were rare in lower sections
of the Green River (Tyus 1987; Lanigan and Tyus 1989). During summer, adult
razorback sucker were most common in shoreline runs and mid-channel sand bars
in the mainstream Green River (Tyus 1987).
Radiotracked fish overwintered in the Jensen, and Island and Echo parks
reaches of Green River (McAda and Wydowski 1980; Valdez and Masslich 1989). In
winter, razorback suckers used slow runs, slackwaters, eddies and backwaters
in the Green River, where local movements increased significantly with flow
fluctuations (Valdez and Masslich 1989).
Razorback suckers in breeding condition were captured primarily on
several cobble/gravel/sand bars in the lower Yampa and upper Green rivers
(including Echo Park and the reach from Ashley Creek to near the lower
boundary of DNM), but were also collected in flooded shorelines, bottomlands,
and tributary mouths (including Old Charley Wash, lower Ashley Creek and
Duchesne River, Stewart Lake Drain; Tyus and Karp, in review). From 1987 to
1989 (low and moderate water years), most ripe fish (98%, n=191) were
collected in flowing water in riffles, but during the high water of 1986, 30%
of all ripe or tuberculate razorback suckers were captured in Old Charley Wash
and Stewart Lake Drain. Twelve ripe adults were observed in Old Charley Wash
in late May-early June 1986 at flows of about 537.7 - 566 m3/s (Tyus and Karp,
in review). These fish were robust and presumed in good physiological
condition due to abundant food in the inundated lowland.
Spawning of razorback suckers occurred during ascending and highest
spring peak flows, as indicated by capture of ripe fish (Figure 8; Tyus and
Karp 1989, in review). Ripe fish were captured at water temperatures averaging
about 14-15°C (Tyus 1987, Tyus and Karp, in review). However, temperatures in
flooded areas (Old Charley Wash and Stewart Lake Drain) in spring 1986 when
ripe razorback suckers were present averaged 19.6°C (range 17.5-21°C). Main
channel temperatures were colder (mean=15.6oC, range 15-16.5°C) at this time
which suggests that razorback suckers may be seeking warmer habitats in the
spring. Bulkley and Pimental (1983) reported that razorback suckers preferred
temperatures of about 22-25°C and avoided temperatures of 8-15°C. Mean monthly
temperatures were reduced at Jensen by operation of Flaming Gorge Dam (G.
Smith, pers. comm.), and current flow and temperature regimens may adversely
affect hatchability of razorback sucker larvae in the upper Green River.
Razorback sucker eggs taken in the Green River experienced poor hatching at
11°C due to fungus, but hatching was successful (90%) when incubated at 20°C
(FWS, unpublished data). Marsh (1985) noted optimal hatch in razorback sucker
larvae at 20°C.
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