7761

• UCREFRP Catalog Number: 7761
• Author: Ryden, D. W. and F. Pfeifer.
• Title: San Juan River Recovery Implementation Program Annual Research Report.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

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INTRODUCTION

Water development and introduction of nonnative 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 range.1 The Colorado squawfish and
razorback sucker are listed as Endangered under the Endangered Species Act
(ESA), and roundtail chub (a Category 2, Notice of Review species) are
protected by the states of New Mexico and Utah. Historical collections
documented Colorado squawfish, razorback sucker, and roundtail chub as members
of the San Juan River fish community.
As a part of the San Juan River Seven Year Research Project, the U.S.
Fish and Wildlife Service's (Service) Colorado River Fishery Project (CRFP) in
Grand Junction, Colorado was given the primary responsibility for adult and
juvenile fish community sampling in the river's main channel habitats. The
adult monitoring study will examine the adult and juvenile fish community of
the San Juan River and together with other studies provide recommendations for
management of river flows to accommodate endangered native fish species. The
objectives of this study are as follows:

1. Increase abundance and distribution data on the native and
nonnative fish community in the San Juan River to examine changes
in this assemblage that may be associated with test flows from
Navajo Reservoir. Special emphasis will be placed on obtaining
data on three rare fish 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.) impede endangered fish movement.

This report represents a summary of the third year (1993) of data
collected on the adult sampling trips and examines the data under items one
through four above. length and weight data are also presented for the first
three years of this study. The information in this report and the inter-
pretations presented are preliminary and subject to change as additional data
become available.

1Scientific and common names for all fishes collected in 1993 are listed"in
Table 2, page 9. Only common names for these fishes are used in the text.

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