8006

• UCREFRP Catalog Number: 8006
• Author: Hawkins, J. A., E. J. Wick and D. E. Jennings.
• Title: Icthyofauna of the Little Snake River, Colorado, 1994 - Final Report.
• USFW Year: 1997.
• USFW - Doc Type: Denver, CO.
• Copyright Material: NO

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INTRODUCTION

The Little Snake River is the largest tributary of the Yampa River and is part
of the Upper Colorado River Basin (Upper Basin). Two endangered fishes,
Colorado squawfish (Ptychocheilus lucius) and humpback chub (Gila cypha) occur
in the Little Snake River (Miller et al. 1982; Marsh et al. 1991; Wick et al. 1991)
and both species have reproducing populations in the adjacent Yampa River (Karp
and Tyus 1 990; Tyus 1 990) but their extent and range in the Little Snake River is
largely unknown. Previous information indicates that some Colorado squawfish
occupy the Little Snake River temporarily just prior to their spawning migration to
Yampa Canyon. In 1981, two radiotagged Colorado squawfish moved from the
Yampa River into the mouth of the Little Snake River in the spring (Miller et al.
1982). In 1988, two other radiotagged Colorado squawfish moved about 10 km
up the Little Snake River and remained there about one month (Wick et al. 1 991 ).
On August 20, 1990, a Colorado squawfish was collected approximately 135 km
upstream of the confluence (Marsh et al. 1991). This capture not only extended
the upstream range of Colorado squawfish into Wyoming, it also extended their
period of occurrence into late summer.

Humpback chub were not collected in the Little Snake River until 1988 when
seven humpback chub and two humpback-roundtail chub (Gila cypha X G. robusta)
hybrids were collected in the lower 1 5 km (Wick et al. 1 991 ). These fish were
caught in early June, approximately during their spawning period and two of the
fish had breeding tubercles suggesting spawning activity. However, none of the
humpback chub collected expressed gametes and additional sampling 20 days later
failed to collect larval humpback chub thus spawning was never confirmed (Wick
et aJ. 1991).

Compared to other rivers in the Upper Basin, sampling for fishes in the
warm-water zone of the Little Snake River has been scant. Because so little
information was known about the fauna of this river, we wanted to assess the