7048

• UCREFRP Catalog Number: 7048
• Author: Desert Fishes Council ‎(Edwin Pister, e.
• Title: Proceedings of the Desert Fishes Council
• USFW Year: 1991.
• USFW - Doc Type: Volumes XX and XXI
• Copyright Material: NO

Twenty-four hour monitoring was done to describe diel movement patterns
and habitat use, and to determine if the 2-hour daylight monitoring represented
diel fish activity. Each fish during year 1 was monitored once for 24 hours,
in randomly selected order. During that time, locations and movements were
checked and recorded at intervals generally not exceeding 2 hours. If a fish
moved to a different location during the 24-hour period and remained stationary
for a substantial time, additional habitat measurements were taken at the new
location. Maps of the river reach occupied by the fish were also completed for
each 24-hour monitoring period, and at least one 2-hour monitoring period was
conducted as described above.
Crepuscular monitoring was conducted to determine if behavior, movement,
or habitat use were different for dawn and dusk as compared to daytime. The
observation period extended from 1 hour before to 1 hour after sunrise or
sunset. Movement and habitat use by each fish was recorded and mapped, and as
with the 2-hour monitoring, habitat measurements were taken at sites occupied
by a fish for longer than 15 minutes. The fish were observed in randomly
selected order within each of the three study regions.
Movement
Movement by the radiotagged fish is classified as either long-range or
local. Long-range movement is associated with fish that changed position in
the river significantly. It is considered transitory because it occurred
between habitats located some distance apart. Long-range movement is
classified as total or net. Total movement is the sum of fish movement in both
up and downstream directions, based on locations during tracking trips. Net
movement is the resultant distance from the original tracking location in early
December to the final location in late March. Long-range movement is expressed
to the nearest 0.1 mile.
Local movement describes the activity of a fish within a localized area,
with no significant change in location. This pattern often involved movement
between two to eight closely-spaced "favorite spots", or microhabitats, within
a single habitat type. Local movement is also classified as gross or net..
Gross movement is the sum of fish movement during a monitoring period. Net
movement is the linear distance between the first and last tracking points.
Local movement is expressed as meters per hour.
Habitat Measurements
Habitat parameters were measured to evaluate habitat use and to relate it
to changes in water surface elevation. These measurement were taken at the end
of the 2-hour, 24-hour, or crepuscular monitoring periods. The following
measurements were taken at each location where a fish was stationary for 15
minutes or longer: water depth; water velocity; water temperature; instream,
bank, and overhead cover; dominant and secondary substrate; ice thickness; and
frazil ice depth.
Measurements were taken from either a boat, by wading, or through a hole
in the ice at three points relative to the fish; the point of triangulation
('point' measurement), one meter toward the river channel ('out' measurement),
and one meter toward the shore ('in' measurement). Measurements were taken at
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