7877

• UCREFRP Catalog Number: 7877
• Author: Anderson, R. M.
• Title: An Evaluation of Fish Community Structure and Habitat Potential for Colorado Squawfish and Razorback Sucker in the Unoccupied Reach ‎(Palisade to Rifle)‎ of the Colorado River, 1993-1995.
• USFW Year: 1997.
• USFW - Doc Type: FA Proj. SE-3,
• Copyright Material: NO

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INTRODUCTION

The upstream extent of the historic range of Colorado squawfish (Ptychocheilus lucius) and
razorback sucker (Xyrauchen texanus) in themainstem Colorado River was probably about 6000 ft
elevation, which is near the town of Glenwood Springs, Colorado (Maddux et al. 1993). Both the
Colorado Squawfish Recovery Plan (USFWS 1990) and critical habitat designation (USFWS 1994b)
use Rifle, Colorado, as the upstream boundary for recovery efforts. The Recovery Implementation
Program Recovery Action Plan (RIPRAP) specifically identifies repopulating the Colorado River
upstream of Palisade with Colorado squawfish and razorback suckers as an important action in
recovery of these endangered fishes (US Fish and Wildlife 1994a).

The decline in number of Colorado squawfish and razorback suckers in the Colorado River
drainage is often attributed to curtailed reproduction associated with manmade alterations to the
ecosystem (Holden and Stalnaker 1975; Seethaler 1978; Wydoski and Wick 1994). Razorback
suckers were known to occur in the IS-mile reach and above the HigWine Dam in the 1970's and
1980's, but have declined to extremely low numbers in recent years (Valdez et al. 1982; Bestgen
1990; Osmundson and Keading 1991; Maddux et al. 1993). Colorado squawfish have not been
collected in the Colorado River above the Highline Dam during recent biological studies (Chuck
McAda, pers comm. unpublished data; Valdez et al. 1982). The loss or disappearance of historic
Colorado squawfish populations above Palisade is primarily attributed to in stream diversion dams,
particularly the Price-Stub and Government HigWine dams, and fish passage structures at these
diversion dams could benefit recovery of Colorado squawfish and razorback suckers by providing
access to more than 50 miles of river now unoccupied (D. S. Fish and Wildlife Service 1994).

This study was established with the intent of formulating a management plan for Colorado
squawfish and razorback suckers for this unoccupied reach. This management plan addresses
in stream flow needs, aspects of nonnative fish control, and a stocking proposal for Colorado
squawfish and razorback suckers. Existing fish population and habitat characteristics of the reach are
presented and are used to make inferences about this area's potential for Colorado squawfish and
razorback suckers in regard to habitat availability, instream flows, forage, and habitat overlap with
nonnative species.

The specific study objectives are:

Objective 1:

To assess habitat availability for all life stages of Colorado squawfish and
razorback suckers in historic, but unoccupied range above Palisade, Colorado.

Objective 2:

To assess in stream flow needs, control of non-native fish impacts, feasibility
and risks of genetic stock management using hatchery-raised fish or natural
recolonization, and monitoring needs associated with reintroduction and
augmentation of these endangered fish in the upper mainstem Colorado River.