7144

• UCREFRP Catalog Number: 7144
• Author: Inslee, T. D.
• Title: Spawning and Hatching of the Razorback Sucker
• USFW Year: 1982
• USFW - Doc Type: Western Association of Fish & Game Agencies
• Copyright Material: NO

34

Species such as Colorado squawf1sh and fathead minnows, however, spend
most of their juvenile life in backwaters. These trends were pointed
out by Holden (1977). The data collected in 1979 agrees with these
generalizations.
The large amount of data collected on Colorado squawfish during
this study adds considerably to our knowledge of the requirements of
that rare fish. The data on preferred seasonal habitat for all sizes
of squawfish complement and strengthen that already available (Holden
1977). The length-frequency information collected during the field
study indicates that both 1978 and 1979 were "banner" years for squaw-
fish reproduction in this portion of the Green River. It also
strengthens earlier data (Holden 1977; Holden and Crist 1978), which
indicated that reproductive success in 1977 was very low in this area.
As mentioned above, young squawfish were found more abundantly
in backwaters that were relatively deep, at least a meter. This does
not mean the young fish were actually caught in this deeper water.
The squawfish were usually captured in areas within a water depth of
.3-.5 meters, which were adjacent to the deeper portions of the back-
water. We hypothesize that the deeper backwaters are more permanent,
i.e., less affected by the daily fluctuations created by Flaming Gorge
Dam, and are, therefore, better habitat for young squawfish for several
reasons. First, the ability of small crustacean (Cladoceran, Copepods)
to produce large populations is enhanced and young squawfish have a
more stable food supply (Vanicek 1967). Second, protection from pred-
ators is enhanced by the availability of deeper areas. Third, the

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