7333

• UCREFRP Catalog Number: 7333
• Author: Valdez, R. A. and W. J. Masslich.
• Title: Winter Habitat Study of Endangered Fish - Green River, Wintertime Movement and Habitat of Adult Colorado Squawfish and Razorback Suckers.
• USFW Year: 1989.
• USFW - Doc Type: Report No. 136-2 for Bureau of Reclamation,
• Copyright Material: NO

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1.0 INTRODUCTION

This Fin;)1 Report is submitted to the Bure;)u of
Reclamation (BOR) in fulfillment of Contract No.
6-CS-40-04490, entitled 'Winter Habitat Study of
Endangered Fish - Green River.' It integrates
the results of a 2-year investigation (1986-87
and 1987-88) of winter habitat use by adult
Colorado squawfish (Ptychochei/us lucius) and
r;)Zorback suckers (Xyrauchen texanus) in the
Green River. The purpose of this investigation
was to characterize the movement and winter
h;)bitat of these endangered fishes, and to
relate these, if possible, to river flow from
November through March between Browns
Park, CO and Ouray, UT.

The objectives of this investigation were as
follows:

1. Determine if adult Colorado squawfish
and razorback suckers overwinter in
specific river regions.

2. Describe wintertime microhabitat
(water column depth, velocity,
substrate, cover and temperature)
used by adult Colorado squawfish
and razorback suckers.

3. Evaluate fish movement and changes
in habitat with changes in flow of the
Green River during the winter months.

2.0 STUDY AREA

This investigation was conducted on the
Green River in Colorado and Utah. The study
area extended from Browns Park, CO (RM 381)
to Ouray, UT (RM 248), and included the Green
River within Dinosaur National Monument and
Ouray National Wildlife Refuge. A map of the
area is provided in Figure 1, and a list of sites
and areas referenced in this report and their

associated river miles, as well as distance from
Flaming Gorge Darn, are presented in Table 1.

This 133-mile reach of river has three
f1atwater sections; Browns Park to Gate of
Lodore (19 miles), Island and Rainbow Parks (7
miles), and Split Mountain to Ouray (72 miles).
It also has three whitewater sections; Canyon of
Lodore (17 miles), Whirlpool Canyon (9 miles)
and Split Mountain Canyon (7 miles). There is
also a short f1atwater section at Echo Park (2
miles) between Canyon of Lodore and
Whirlpool Canyon. After electrofishing efforts in
October 1986 yielded no Colorado squawfish or
razorback suckers between Browns Park and
Echo Park, that 35.9-mile section in the upper
part of the study area was abandoned, except
for aerial tracking. This reduced the study area
to 97.1 miles.

Access to the river w;)s from eleven boat
launches (Table 1), including the Lodore
Ranger Station, Echo Park, Ruple Ranch,
Rainbow Park, Split Mountain, Park Service
"Bone Yard', Ashley Creek, Bonanza Bridge,
Horseshoe Bend, Ouray Refuge, and Ouray
Bridge.

For the purposes of this investigation, the
study area was divided into upper, middle and
lower regions according to stream gradient and
river morphology. TIle upper region from Echo
Park to lower Split Mountain Canyon (25.3
miles) has a relatively steep gradient with
primarily a gravel-boulder -bedrock substrate.
The middle region from lower Split Mountain
Canyon to Jensen Bridge (18.3 miles) has a
moderate gradient with a gravel-cobble
substrate in the upper reaches and a sand
substrate in the lower reaches, and the lower
region from Jensen Bridge to Ouray Bridge
(53.5 miles) is. a low-gradient, meandering river
with primarily a sand substrate.

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