9552

• UCREFRP Catalog Number: 9552
• Author: U.S. Fish and Wildlife Service.
• Title: Management Plan for the Big-River Fishes of the Lower Colorado River Basin
• USFW Year: 2004.
• USFW - Doc Type: amendment and supplement to the Bonytail, Humpback chub, Colorado pikeminnow, and Razorback sucker Recovery Plans.
• Copyright Material: NO

1

15,000 individuals have been made for the Little Colorado River
population (Douglas and Marsh 1996; Minckley 1988, 1989, 1990x,
1990b; Valdez and Ryel 1995). The most recent estimates made in the
spring and fall of 2002 were 2,666 humpback chubs (spring) in the Little
Colorado River > 15 cm; 2,002 of these fish were > 20 cm. The fall
estimate for 2002 was 2,774 humpback chubs >15 cm in the system; 839
of these fish were >20 cm {VanHaverbeke 2002, 2003). This is a marked
decline from estimates made in 1992 that estimated the population size
between 4,500 - 5,500 individuals >15cm (Douglas and Marsh 1996).
Most of the reproduction occurs in the Little Colorado River, although
limited reproduction does occur in the mainstem Colorado River. (Minckley
1990, Valdez and Ryel 1995). This species exhibits migratory behavior in
and out of the Little Colorado River during spawning activities (April -
May). More larger fish are present in the system in the spring than in the
fall due to these movements (VanHaverbeke and Goggins 2003). Factors
impacting this population include the release of cold hypolimnectic water
releases from Glen Canyon Dam, competition/predation by nonnative: fish,
and parasitism.
Research activities on humpback chub fall under the purvue of the
Adaptive Management Work Group (AMWG) associated with the Grand
Canyon Protection Act of 1992. The AMWG has the responsibility of
defining management objectives associated with the resources
downstream of Glen Canyon Dam, and developing along-term monitoring
program to assess those resources. The Grand Canyon Monitoring and
Research Center (GCMRC) is responsible for implementing the long-term
monitoring program and assuring that it meets the needs of AMWG. In
this role, GCMRC has initiated a program that focuses on stock
assessment of humpback chub for future long-term monitoring of Grand
Canyon fishes (VanHaverbeke and Coggins 2003). Another component
of the long-term monitoring includes monitoring the humpback chub
population in the Colorado River.
Applicable Recovery Goals and Management Strategies:
Recovery Goal: Maintain one self-sustaining population while
moving toward recovery.
Downlisting Criteria:

15