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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since it exhibits seasonal differences and does not, at any given time, provide
the fish with a full variety of choices. CUrrent year-round investigations may
eventually shed some light on this matter. Cover was identified as the fifth
habi tat parameter that may be used for generating HSI curves. It was noted
that very little, if any, cover is identified in the database, and the experts
agreed that there are insufficient data to generate category 2 curves.
However, cover was identified as a habitat parameter important to nonspawning
adult humpback chub in the Colorado, Green, and Yampa rivers, and the experts
agreed to try and generate category 1 curves to describe the steep vertical
rock faces associated with the species in Black Rocks, Westwater Canyon,
Whirlpool Canyon, and Yampa Canyon.

STRATIFY, POOL, AND ANALYZE DATA

Methods

In most cases, the five experts decided, by consensus, on the data to be
included in analyses for possible curve development. Where the experts were
uncertain, BIOjWEST was asked to 'test' or 'decision/test' the depth, velocity,
and substrate data, independently. If a 'test' was specified, the depth or
velocity data were to be pooled when the Kolmogorov/Smirnov 'D' value was
greater than 0.05, indicating no significant difference between partitions.
The partitions were to be retained if the 'D' value was less than pr equal to
0.05, indicating a significant difference between partitions (See METHODS USED
TO POOL DATA under TASK C for a description of these statistical tests).
Similarly, substrate data were to be pooled if the Chi-square test yielded an
alpha level greater than 0.05, and not pooled if the alpha level was less than
or equal to 0.05. If the number of samples (number of fish with associated
habi tat measurements) in one or both parti tions was less than 20, the
partitions were automatically pooled where a 'test' had been specified.

No pooling was to be performed under a 'decision/test,' but the statistics
were reported in the Draft Report as a tool for the decision-making process
during Workshop #2. A 'decision/test' was used because the experts felt that
certain partitions of data should be retained, but they wanted to see
sta ti sti cal tests among these partitions to confi rm or refute thei r
professional judgement. The experts also reserved the option of later pooling
partitions that had been retained through a 'decision/test.'

Results

The 291 data partitions identified by the experts in Workshop :!tl were
tested by BIOjWEST in the manner specified by the experts. These were pooled
or partitioned according to the predetermined test guidelines in preparation
for Workshop #2. These data partitions ,the tests and decision/tests, and the
parti tions to be used for developing preliminary HSI curve are presented
graphically in the dendrograms in Figures 1-8. Each preliminary HSI curve is
identified as a category 1 or category 2 curve (Bovee 1986). A category 1 HSI
curve is developed from expert judgement and/or supplemental data. A category
2 HSI curve is developed from field data, and may be called a "utilization"
curve.

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