7154

• UCREFRP Catalog Number: 7154
• Author: Holden, P. B.
• Title: Habitat Requirements of Juvenile Colorado River Squawfish.
• USFW Year: 1977.
• USFW - Doc Type: FWS/OBS-77/65,
• Copyright Material: NO

37

a readily available food source for both young-of-the-year and juvenile
squawfish and it appears very likely that an abundance of these preferred
habitats may well increase the survival potential of young squawfish.

primarily from the standpoint of food availability, If this hypothesis

is correct, preferred habitat of Y.C>.!.lUg.,IJl~~Y, in fact, ~~ a limiting factor
~_, .,..,'_,.____,_"__..,,. ,_,. ~ -- ., - -'.' , ,..",.". \ ~ -. -'-'-",. ,-' ._".>.,"'Y-',"><

to rare fishes, especial1:vColaradQ squawfish.
The low water levels encountered during the study reduced the
available number of small backwaters from normal levels. A large number
of potential backwater situations were seen in the study area that, given

1-2 feet of additional flow, would have been preferred young squawfish
habitat. The cross-sectional data of Figures 12 and 13 indicate that
that particular area had certain depth and velocity categories present,
Very little preferred habitat (Figure 2) of young-of-the-year squawfish

was present, except in the backwater where they were found. Cross-sec-

tional data from other areas of young-of-the-year squawfish habitat would

provide comparative data.

Rare Fish Movements and Potential Spawning Areas

The three young-of-the-year squawfish recaptured in the sample
backwater provide little data on movement. The fact that a relatively
large number of fish were marked and that successive samples found re-
latively large numbers of unmarked fish, indicates several possibilities,
First, a fairly large population is indicated. Secondly, failure to re-
capture marked fish suggests either low sampling efficiency or absence of

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