6006

• UCREFRP Catalog Number: 6006
• Author: Holden, P. B. and L. W. Crist.
• Title: Documentation of Changes in the Macroinvertebrate and Fish Populations in the Green River Due to Inlet Modification of Flaming Gorge Dam
• USFW Year: 1981.
• USFW - Doc Type: Final Report.
• Copyright Material: NO

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conditions were determined with the aid of a literature review, as well
as portions of the 1978 data.
Field sampling was conducted in March, June, August, and October of
all years. A July sample was added in 1978 in an attempt to increase
the amount of "before" data. Macroinvertebrates and fish samples were
both taken during each sampling period. Yampa River samples were taken
only in June, August, and October of 1978, and the Lower Yampa station
was not sampled in March of 1979 and 1980 due to inaccessibility.
Macroinvertebrates
Macroinvertebrates were sampled in cobble-rubble substrates in a
stratified random sampling design at each of the six stations. A Hess
type invertebrate sampler was used to obtain a one square foot sample.
Four samples were taken at each station. The samples were preserved in
70% ethyl alcohol in Whirl-Pak bags, and transported to BID/WEST's lab
for analysis. High water samples were avoided in the Green River above
Echo Park by proper timing of collection, except at Wade and Curtis.
Samples containing fewer than 400-500 organisms were sorted in their
entirety. Samples with larger numbers of organisms were initially
sorted to remove large organisms such as stoneflies and any uncommon
smaller organisms. The sample was then subdivided by a rotary device
which portions the sample into eight equal subsamples. Subsamples were
randomly chosen and counted. The number of subsamples enumerated was
dependent on the numbers of organi sms. Generally, the 1 arger the num-
bers of invertebrates in a sample, the fewer the number of subsamples
necessary. In each case, at least ~ of each sample was picked to avoid

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