7888

• UCREFRP Catalog Number: 7888
• Author: Minckley, W. L.
• Title: Native Fishes And Natural Aquatic Habitats In U.S. Fish And Wildlife Service Region II West Of The Continental Divide, A Review of Population and Habitat Status and Evaluation of Survival Potentials for Native Freshwater Fishes, with Recommendations.
• USFW Year: 1985.
• USFW - Doc Type: \
• Copyright Material: NO

INTRODUCTION

Water development and introduction of non-native species of fish
have had a profound effect on the native fish fauna of the San Juan River.
Some native species such as Colorado squawfish, razorback sucker, and
roundtail chub have become rare throughout their native habitats.' The
Colorado squawfish and razorback sucker are listed as Endangered under the
Endangered Species Act (ESA), and roundtail chub are protected by the states
of New Mexico and Utah. Historical collections documented the Colorado
squawfish, razorback sucker, and roundtail chub as members of the San Juan
River fish community.
The U.S. Fish and Wildlife Service's Colorado River Fishery Project
(CRFP) in Grand Junction, Colorado was given the primary responsibility for
adult (and juvenile) fish sampling in the river's main channel habitats. The
adult monitoring study will examine the adult fish community of the San Juan
River and together with other studies provide recommendations for the
management of river flows to accommodate endangered native fish species. The
objectives of this study are as follows:

1. Refine abundance and distribution data on the native and non-
native fish community in the San Juan River, with emphasis on
three rare species (Colorado squawfish, razorback sucker, and
roundtail chub).

2. Locate potential spawning areas of rare species.
3. Determine habitat use and needs of rare species.

4. Evaluate movement data to determine the extent to which current
structures (dams, weirs, etc.) are impeding endangered fish move-
ment.

This report represents a summary of the first two years (1991 and 1992)
of data collected on the adult sampling trips and examines the data under
items one through four above. The information in this report and the inter-
pretations presented herein are preliminary and subject to change as
additional data becomes available.

'Scientific and common names for all fishes collected in 1991 and 1992 are
listed in Table 2, page 9. Only common names for these fishes are used in
the text.

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