7908

• UCREFRP Catalog Number: 7908
• Author: Valdez, R. A. and R. J. Ryel.
• Title: Life History and Ecology of the Humpback Chub ‎(
• USFW Year: 1995.
• Copyright Material: NO

1-4 . Chapter 1

Conservation Measure 5: Conduct research to
identify impacts of Glen Canyon Dam operations on
the humpback chub in the mainstem and tributaries.

Conservation Measure 6: Establish a long-term
monitoring program to assess the relationship of
project operations to the humpback chub.

Conservation Measure 7: Establish a second
spawning population of humpback chub in the
Grand Canyon.

Conservation measures 5 and 7 provided the
framework for the purpose and objectives of the
BIW investigation, as detailed in the following
section. These measures also guided study designs
of other investigations as part of the Phase II DIRP.

On July 27, 1989 Secretary of Interior, Manuel
Lujan, directed the initiation of an Environmental
Impact Statement (EIS) on the Operation of Glen
Canyon Dam. Passage of the Grand Canyon
Protection Act of 1992 (PL 102-575) on October
30, 1992 mandated completion of a Final EIS no
later than 2 years after the date of enactment (Sec.
1804). Most of the NEF Studies identified in Fig.
1-2 were not completed in time for the Draft EIS,
and only preliminary findings and results were
provided from this BIW investigation to the EIS
Team.

PURPOSE AND OBJECTIVES

The purpose of this investigation, as stated in
Reclamation Contract No. 0-CS-40-0911O to BIW
,
was to:

"Evaluate the ecological and limiting factors of all
life stages of humpback chub in the mainstem
Colorado River, Grand Canyon, and the effects of
Glen Canyon Dam operations. "

This investigation was designed to describe
physical, chemical, and biological components of
the Grand Canyon aquatic ecosystem and to identify
principal factors limiting the survival and
proliferation of the endangered humpback chub.
This investigation addressed only certain aspects of
these components and was designed to share roles
and responsibilities with other investigations, as
outlined in Table 1-1.

Final Report

The study objectives for BIW were to determine the
following attributes for humpback chub in the
mainstem Colorado River in Grand Canyon:

~ Distribution, abundance and movement.
~ Survivorship of early life stages.
~ Reproductive capacity and success.
~ Resource availability and use (i.e., habitat,
food).
~ Important biotic interactions with other species
for all life stages.
~ The life history schedule.

These objectives were developed by Reclamation as
part of the NEF Studies to address Conservation
Measures 5 and 7 and to provide insight into
Question 6 and Hypotheses Ho-6.1, Ho-6.1a, and
Ho-6.1b of the Phase II DIRP (Volume 1, pages
10-11). Question 6 and the associated DIRP
hypotheses are addressed in Chapter 10 -
INTEGRA nON of this report.

Question 6: "How do discharge fluctuations and
rates of change in fluctuating discharges affect other
fish, especially native fish species? Do the USFWS
(Service) Conservation Measures adequately
address this question?"

Ho-6.1: "There is no significant relationship
between the population dynamics (including short-
term abundance of early life stages and potential
predation relationships) of native (especially the
humpback chub) and introduced fish species in the
mainstem Colorado, including mainstem backwaters
and the confluence of the Little Colorado, and the
magnitude of fluctuations, minimum discharges and
rates of change of fluctuating discharges."

Ho-6.1a: "There is no significant relationship
between population dynamics of native and
introduced fish species in the mainstem Colorado,
including backwaters and tributaries, and the
magnitude of discharge fluctuations."

Ho-6.1 b: "There is no significant relationship
between population dynamics of native and
introduced fish species in the mainstem Colorado,
including back'Waters and tributaries, and the
magnitude of minimum discharges."