1106

• UCREFRP Catalog Number: 1106
• Author: Gosse, J.
• Title: Microhabitat of Rainbow and Cutthroat Trout in the Green River Below Flaming Gorge Dam.
• USFW Year: 1982.
• USFW - Doc Type: Logan, UT.
• Copyright Material: NO

xi

by depth from the other fish.
As nearly as can be determined, the juvenile cutthroat trout
emigrated from most of the study area during the first week of
the high flow test. There was no apparent physical reason for
the emigration. The other life stages exhibited no changes dur-
ing~the entire high flow test per~od. There was no indication of
excessive velocities during the high flow test.
During March and April, the months following the high flow
tests, there appeared to be a gradual decline in the number of
fish, particularly the juvenile rainbow trout. None of the mi-
crohabitat variables indicated any reason for the decline.
There was no indication that high flows either forced the
fish to swim in velocities above those normally utilized or that
they had to utilize marginal habitat to obtain preferred veloci-
ties. If high flows playa part in fish emigration, it appears
that they are indirectly correlated. Two possible correlations
may be th~ high flows at certain times of the year serve as a
trigger to stimulate emigration or that winter high flows result
in gas supersaturation or aggrevate other unknown water quality
problems. Juveniles were more prone to emigration than adults.
It is possible that the size of juveniles is also important in
determining whether they will emigrate.

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