9569

• UCREFRP Catalog Number: 9569
• Author: Valdez, R. A.
• Title: Synthesis of Winter Investigations of Endangered Fish in the Green River Below Flaming Gorge Dam.
• USFW Year: 1994.
• USFW - Doc Type: 18-11,
• Copyright Material: NO

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ABSTRACT

Recent investigations by Valdez and Masslich (1989) and Wick and Hawkins (1989)

on radiotagged adult Colorado squawfish and razorback suckers in the Green River and

Yampa River revealed a fidelity for overwintering sites in moderately deep, low-velocity

habitats. Both species were locally active, but rarely left a habitat, except during flow

changes or to avoid ice jams and frazil ice masses. Low, relatively stable winter flows are

recommended to stabilize low velocity habitats, allow formation of a persistent ice cover to

insulate flows from supercooling, dampen moderate fluctuations, and minimi7.e incidence of

ice jams and frazil ice. Further research is recommended to ascertain needs of other life

stages of Colorado squawfish, razorback suckers, humpback chub, and other native species.

Recommended studies include (1) a physical model of ice processes, (2) assessment of flow

regulation and ice on overwinter nursery habitat, (3) evaluation of physiological effects of

supercooled water on survival of age-O Colorado squawfish, (4) assessment of Colorado

squawfish nursery habitat, (5) estimate of overwinter survival of age-O Colorado squawfish,

(6) survey of the Lake Powell inflow for Colorado squawfish, (7) evaluation of winter and

spring flows on movement, dispersal and survival of young Colorado squawfish, and (8)

assessment of predation on age-O Colorado squawfish in supercooled winter conditions.

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