7984

• UCREFRP Catalog Number: 7984
• Author: Maddux, H. R., L. A. Fitzpatrick and W. R. Noonan.
• Title: Colorado River Endangered Fishes Critical Habitat - Draft, Biological Support Document.
• USFW Year: 1993.
• USFW - Doc Type: Salt Lake City, Utah.
• Copyright Material: NO

Razorback suckers were once more abundant and widespread in the Lower Basin. However,
razorback sucker maybe more recoverable in the Upper Basin because habitat in the Upper
Basin has been less altered, and current habitat conditions warrant proposing a large
percentage of the Upper Basin (Figure 7). Approximately equal amounts of Upper (944) and
Lower Basin (880) river miles have been proposed (Table 2).
These reaches flow through a variety of shoreline ownerships, both public and private. The
National Park Service is the major manager for proposed critical habitat with 33 percent of
shoreline ownership. The approximate percentages of critical habitat by shoreline ownership
for the razorback sucker is presented in Figure 8.
RAZORBACK SUCKER CRITICAL HABITAT DESIGNATION BY AREA
Yampa River - Lily Park to Green River Confluence
Boundary Delineation: Colorado, Moffat County. The Yampa River and its 100-year
floodplain from the mouth of Cross Mountain Canyon in T.6N., R.98W., section 23 (6th
Principal Meridian) to the confluence with the Green River in T. 7N., R. 103W., section 28
(6th Principal Meridian).
Shoreline Ownership: National Park Service, 82.9 percent; Private 16.9 percent; Bureau of
Land Management, 0.2 percent.
Overlap with Proposed Critical Habitat for: Colorado squawfish, humpback chub,
bonytail.
Occurrence:
Historical
The historical distribution of the razorback sucker in the Yampa River is difficult to assess
due to limited data from early collections (Bestgen 1990). Historical accounts indicate
razorback suckers were common from the Lily Park area to the Green River (Quartarone
1993).
Recent
Recent collections indicate that the fish occur in the lower portions of the river, but rarely
upstream of the confluence with the Little Snake River (McAda and Wydoski 1980; Lanigan
and Tyus 1989). Concentrations of the razorback sucker were found near the Green River
confluence (Holden and Stalnaker 1975a, 1975b). Carlson et al. (1979) presented data that
showed the razorback sucker to be present at Lily Park. Spawning razorback suckers were
found in the lower Yampa Canyon (Miller et al. 1982b; Tyus and Karp 1989, 1990).
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