3110

• UCREFRP Catalog Number: 3110
• Author: Sublette, J. E.
• Title: Survey Of The Fishes Of the San Juan River Basin, With Particular Reference To The Endangered Species.
• USFW Year: 1976.
• USFW - Doc Type: Albuquerque, New Mexico.
• Copyright Material: NO

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A suaVEY OF THE FISHES OF THE SAN JUAN RIVER BASIN .

WITH PARTICULAR REFERENCE TO THE ENDANGERED SPECIES

by

James E. Sublette

Introduction

The Endangered Species Act of 1963 has given new impetus to ecological and

zoogeographic studies of native southwestern fishes. In the San Juan Basin

several species mentioned in previous reports (Olsen 1962a, b, 1968, Koster 1963,

Olsen and HcNall 1965, Smith 1966, Holden 1968, Graves and Haines 1969) are

thought to have undergone change in population numbers in the intervening years.

This survey was conducted to determine the status of the squawfish,

Ptychocheilus Lucius Girard, an endangered species, in the San Juan Basin, as

well as the oth~r components of the ichthyofauna.

~taterials and Methods

Fish were collected at 34 stations on the San Juan River and its principal

tributaries in Colorado, New Mexico, and Utah (Fig. 1; Appendix II). The main.

collecting method was by use of a 10' x 4' minnow seine of 3/16" mesh. In those

situations where the bottom type permitted its use a 25' x 4' bag seine of 1/4"

mesh was used.

A limited number of gill net sets using several mesh sizes was made. in

Navajo Reservoir and on the main stream San Juan near Bloomfield, New Mexico.

Several sets on the main stre3111 San Juan were negative due to the nets becoming

quickly fouled wIth large amounts of drifting filamentous algae.

An electric seine was used under the supervision of Mr. Ben Robertson.

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U.S. Fish and Wildlife Service, on the Piedras and Pinos Rivers in Colorado

(Stations 7 and 8). A portable boat mounted boom shocker was also used at

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Station 8 (Los Pinos River) and Station 34 (Lake Powell, San Juan Arm).

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