7159

• UCREFRP Catalog Number: 7159
• Author: Hagen, H. K.
• Title: Progress Report on Ecological and Limnological Studies of the Green River in Dinosaur National Monument.
• USFW Year: 1963.
• USFW - Doc Type: Fort Collins, Colorado.
• Copyright Material: NO

The crew left Island Park and traveled at night to Echo Park. The
following mo~ning they speut shocking and seining the junction areas
of the Green and Yampa Rivers. The afternoon was spent sampling the
station at C tle Park on the Yampa River.

Crew No. 2 traveled to Echo Par_~_ijnd spent the first full day
sampling the river in that reaion.- Duplication of effort was intended
because of the strategic location of Echo Park at the confluence of the
Green and Yarnpa Rivers. Fis~-E2Eulations in this sec~~l:QIlj.Ill96l were
abundant and contained a greater number ~f~ecies fll of 13 recorded)
than any other single station. If the kill in tl1~_}10IJ.~Ilt~a~s consider-
able, t~n shQuld be 'reflect IVe:=of'_the-kill since it had the
advantage of the greatest source of dilution of any section from the
waters of the Y~-crew traveled at night to the Gates of Lodore
and spent the entire second day sampl1Dg the river there. A side channel
of the stream where many fish had been taken previously by Mr. Banks
was intentionally poisoned with a rotenone based poison at a level in
excess of 2 p.p.m. of toxin.

One crew member of each unit vIas assigned the responsibility of
taking at least four square foot bottom samples from each station.
Larger collections were not made because Mr. Banks was to continue
bottom sampling at a later date.

( Results of the study will be contained in a final report to be sub-
I mitted in J\.Ule, 1963 when all data have been fully evaluated and
f analyzed. A few observations, however, can be presented concerning the
J condition of the fish and invertebrate populations after the toxin had
L-run its course in the Monument.

Collecting efforts in 1962 were equally as intensive as in 1961.
Conditions were much better for collecting fish in 1962 than they were
in 1961 because the rivers were at the lowest point that they had been
in several years. If fish were present they should have been concentrated
and much easier to capture. In addition to this, the electric e;enerator
which sa.w only limited use in 1961, was functioning exceptionally well
in stunning fish.

Total numbers of fish taken in 1962 are listed by station in
Table 1. It was estimated that about one-half or less of the fish
stunned at Split l~untain were recovered. The majority of the fish not
recovered were large carp since the men made every effort to collect a
m~~imum number of species and would by-pass a large carp if they had
to make a choice in taking it or a fish of another spec ies. The same
percentage of recovery was estimated at Island Park but there, equally
as many very large flannel-mouth suckers were by-passed as were carp.
A~ho Park" nearly every f~ turned over was taken. NO-ln9~e than
six or possibly ten fish were seen to have escaped the nets. EvelJr
effort was made to take all the fish encountered in the sampling station
at Castle Park on the Yampa River.

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