1103

• UCREFRP Catalog Number: 1103
• Author: Holden, P. B.
• Title: Study of The Habitat Use and Movement Of The Rare Fishes In The Green River From Jensen To Green River, Utah, August and September, 1977
• USFW Year: 1977.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

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knowledge, the first young razorbacks reported from the upper Colorado
Basin. A more detailed taxonomic analysis of these specimen~, including
comparison with known razorbacks from Willow Beach National Fish Hatchery,
will be carried out in the near future to verify the preliminaryidenti-
fication.

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Preferred Habitat of Rare Fishes

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The data from this study show that young-of-the-year an!d juvenile
squawfish prefer backwaters where there is little or no cur~ent and a
silt bottom. Juveniles prefer deeper areas than young-of-the-year.
Vanicek (1967) indicated that young squawfish (age groups O~II) were
found in areas where IIcurrent was slight or lacking.1I Hold~n and
Stalnaker (1975) found young-of-the-year in shallow backwaters and ju~
veniles in backwaters and eddies 2 to 3 feet in depth.
The data indicate that subadult squawfish prefer runs ~nd eddies
as opposed to backwaters. Vanicek (1967) found a similar p~ttern.
Holden and Stalnaker (1975) indicated that slow water was preferred to
runs and fast eddies, and backwaters were used during high water. A
collecting trip in May of 1976, conducted by the Colorado River Fishes
Recovery Team from Jensen to Ouray, produced approximately ~Osubadul t
and adult squawfish. All of these fish were taken in backw~ters. These
data suggest that larger squawfish in the Green River may c~ange habitat
preference with season. During high water (spring and early summer)
backwaters appear to be preferred; whereas, during low watet (fall) ed-
dies and runs are predominantly used. Kidd (1976) indicated that

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