6037

• UCREFRP Catalog Number: 6037
• Author: U.S. Fish and Wildlife Service.
• Title: Endangered Colorado River Habitat Utilization Curves-Draft.
• USFW Year: 1984.
• USFW - Doc Type: \
• Copyright Material: NO

Title: Adult Colorado squawfish prespawning temperature utilization
curve.
Parameters: Mean monthly temperature (C ).
Period: I Mar - 1 Jul, Colorado River
1 Mar - 1 Jun, Green River
1 Mar - 1 Jun, Yampa River
1 Mar - 1 Jun, White River
Data utilized:
1. USGS temperature records for Maybell, Jensen, Stateline, Ouray,
and Green River, Utah gauges.
2. Criteria were based upon monthly mean temperatures for the
periods of record. The minimum monthly mean, the mean of monthly
means, and the maximum monthly mean were used to establish the
three points of the utilization curve.
3. The maximum temperature limit was derived from studies conducted
at the University of Utah (Berry et. al. 1980) that established
the critical thermal maxima at 35 C. Thirty-two was selected as
a temperature reasonably close to that maximum but short of that
-impacting temperature.
Data excluded:
Single point and miscellaneous thermograph records collected by CRFP
because their discontinous and widely distributed sites make them
impractical for broad application.
Assumptions:
Observed prespawning temperatures are close to pre-development
conditions and thus satisfactory for gonatal development, stimulation
to migrate and spawning.
Constraints:
1. Curves are developed for each major river reach occupied by adult
Colorado squawfish and are applicable only to those reaches.
2. These criteria apply only to the gauging stations from which they
were derived. Data varied widely in quality from continuous
records to grab records requiring considerable differences in
computation of criteria. These criteria are appropriate to only
the type of data from which they were derived and are unique to
each gauging station.
3. These curves only reflect conditions of record; they do not
necessarily reflect optimum temperature regimes.
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