7332

• UCREFRP Catalog Number: 7332
• Author: Valdez, R. A., et al.
• Title: Final Report Habitat Suitability Index Curves for Endangered Fishes of the Upper Colorado River Basin.
• USFW Year: 1987.
• USFW - Doc Type: \
• Copyright Material: NO

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1. a water routing model for the basin;

2. a water temperature simulation model for the basin;

3. hydraulic simulations at selected river cross sections important to
the life history of the endangered fishes; and

4. quantitative criteria describing the physical habitat requirements of
the endangered fishes.

Since 1984, data have been collected and experience has been gained in
understanding each of the activities noted above. Integration and filling the
data gaps, which will constitute the next phase, cannot be accomplished until
certain basic information is gathered and concepts are developed and verified
within these four activities. Numbers one and four are the principal drivers
of any successful integrated basinwide analysis. Once water movement
throughout the system and the habitat needs of the key life stages of the
endangered fishes are described, then, and only then, can items two and three
be fine-tuned to match the outputs of one and four.

Considerable work has been done by the hydrology group toward meeting the
objectives of number one (i.e., the stream routing model HYDROSS has been used
and modified to describe the upper basin and water delivery through all the
specified riverine habitat areas identified). The ability to predict flow
condi tions at various points wi thin the basin using a monthly time step has
been achieved to the general satisfaction of the hydrological community.

It is the purpose of thi s report to focus on item number four, a
description of the physical habitat requirements of the endangered fishes of
the Upper Colorado River system. Considerable data have been collected since
the mid-1970's describing the physical conditions present where these fishes
were captured. However, most of this has been incidental to general ecological
studies of the life history, distribution, and abundance of the fish species.
General disagreement as to the degree of certainty with which the habitat
requirements were known for these endangered species led the Fish and Wildlife
Service to award a contract for the purpose of: (1) bringing together all the
known habitat information into a common database; (2) analyzing and summarizing
those data; (3) convening a panel of species experts to evaluate the existing
information and develop habitat suitability criteria for those habitat
parameters and species life stages for which sufficient data and knowledge
existed. This document reports that process and the status of the information
and understanding of the habitat needs of the Colorado River endangered fishes.
The important next step is to focus ongoing Colorado River fishery research
toward improving the understanding of habitat needs for those life stages which
this report shows are not well known, and collecting data in such a manner that
allows for valid habitat suitability criteria to be developed. For this reason,
the habitat suitability curves presented in this document are considered
interim curves and most surely will be refined as a result of ongoing research
programs. The immediate benefit of this particular exercise should be the
refinement of the temperature simulation effort and the description of
microhabitats and sampling procedures for hydraulic simulations.

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