9435

• UCREFRP Catalog Number: 9435
• Author: Haines, B. and T. Modde.
• Title: Humpback Chub Monitoring in Yampa Canyon, 1998-2000.
• USFW Year: 2002.
• USFW - Doc Type: Project Number 22a4,
• Copyright Material: NO

Introduction

The humpback chub (Gila cypha) is endemic to the Colorado River basin and occurs only

in isolated populations in narrow canyon bound reaches of the mainstem Colorado River and its

major tributaries. The largest population, consisting of four or five thousand fish (Douglas and

Marsh 1996), occurs in the lower Colorado River basin in the Grand Canyon and Little Colorado

River reaches. The upper basin has five smaller populations: Desolation/Gray canyons in the

middle Green River, Cataract Canyon in the Colorado River above Lake Powell, Westwater

Canyon in the Colorado River in eastern Utah, Black Rocks in the Colorado River in westem

Colorado, and Yampa Canyon in the Yampa River in northwestem Colorado.

Little is known about humpback chub in Yampa Canyon, because of an inaccessible

canyon reach, confusing Gila taxonomy, and its rare status. The first documented humpback

chub captures were in 1948 in the Castle Park area (Tyus 1998), and a few fish were collected in

the 1960s at the Yampa River/Green River confluence (Karp and Tyus 1990). In the mid-1970s,

it was recognized that humpback chub was rare in Yampa Canyon (Miller et al. 1982). From

1987 to 1989 the Colorado River Fish Project at Vemal, Utah conducted a standardized

monitoring program that consisted of electro fishing and angling in Yampa Canyon, Lodore

Canyon, Whirlpool Canyon, and Split Mountain Canyon (Karp and Tyus 1990). The

standardized monitoring found that the humpback chub population in Yampa Canyon consisted

of adults and juveniles and concluded that the population was reproducing. However, almost

nothing is known about population size, survival, recruitment rates, and population trends.

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