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

v

Fish were located and observed by a diver using a modified

scuba technique.

The diver wore an exorbitant amount of weight

to enable him to remain stationary on the stream bottom in the

strong currents. An underwater communication system allowed the

diver to transmit microhabitat data to the surface personnel.

The diver made microhabitat measurements as nearly as possi-

ble to each fish's precise location. Most microhabitat variables

could be measured by the diver without assistance and the data

were relayed to the surface personnel. Velocity and (initially)

light measurements were made by the diver placi~g the respective

probe in position and instructing the surface personnel to read

the surface meter.

T~ six variables used to describe trout microhabitat in

thi s study were:

fish velocity, mean column velocity, fish

depth, water depth, substrate type, and overhead light. Fish

velocity was defined as the water velocity measured at the pre-
cise location where the fish was observed. Mean 'velocity was de-

termi~cd at four-tenths of the water column height occupied by
the fish, measured from the river bottom. Velocities were meas-

ured with an electronic current meter. Fish depth, the distance

of the fish from the stream bottom, was estimated by the diver to

the nearest 5 em.

Water depth was measured by using a depth

gauge for most of the study. Substrate type was categorized as

rock, rubble, gravel, silt or other. Presence or absence of

pl ant .coverwas also recorded.

The 1 evel of overhead 1 i ght

reaching the fish was measured with one of two types of electron-

ic illuminance meters.

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