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: Colorado squawfish post-larval YOY depth utilization
curve
Parameters: Water column depth (ft)
Period: Year around
Location: All river reaches within post-larval YOY Colorado
squawfish distribution
Data utilized:
1. Water depth data from YOY annual sampling collections in
backwaters on the Green River (1979-1982) and Colorado River
(1982-1983).
2. Water depth data from Colorado River intensive YOY collections
(1979-1981) pooled.
Data excluded: '
1. Green River YOY collections and diel Green River data
because of large volume of more representative data
collected during YOY standardized sampling.
2. Green River 1983 YOY standardized sampling data because
abnormally high flows significantly altered habitats occupied by
YOY Colorado squawfish.
3. Colorado River data for hatchery reared Colorado squawfish
because of potential difference in behavior patterns.
4..A11 shoreline and other habitat collections except
backwaters because samples demonstrated a strong preference
for backwaters over all other habitats.
Assumptions:
1. Catch per unit of effort is a true reflection of habitat
preferred.
2. Spring and fall depth preferences are not significantly
different.
3. No signifcant difference in depth preferences between
Green and Colorado Rivers.
4. Mean depth measurements for individual seine hauls
reflect true depth preferences for YOY Colorado squawfish.
Constraints:
1. Curves apply only to the Green and Colorado Rivers
occupied by Yoy Colorado squawfish. Not applicable to
the Yampa, Gunnison, White or Green River above the
Yampa confluence.
2. Curves apply only backwater type habitats preference and
should not be applied to stream channel model not
containing backwater habitats.

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