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Last modified
7/14/2009 5:02:33 PM
Creation date
5/17/2009 11:08:08 PM
Metadata
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UCREFRP
UCREFRP Catalog Number
8135
Author
Valdez, R. A.
Title
Occurrence of Threatened and Endangered Fishes of the Colorado River in the Vicinity of the Proposed Jacobson Hydro No. 1 Project.
USFW Year
1984.
USFW - Doc Type
Logan, Utah.
Copyright Material
NO
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<br />. <br /> <br />3-2 <br /> <br />Long-handled dip nets with small-mesh (1/16-inch) bags were used to <br />synoptically sample the shallow areas for larval fishes. These were <br />particularly effective in shallow shorelines where fish were visible. These <br />dip nets and the seines described above were used to supplement capture <br />information from electrofishing and drift nets. <br />A systematic program of drift netting was conducted at the proposed <br />project intakes on the present Price-Stub Dam during a time when most larval <br />drift is known to occur in the Upper Colorado River (Valdez and Carter <br />1983). This program was initiated July 13 and was completed September 14, <br />1984. It was initiated when water temperatures reached 16 C and when larval <br />fish first appeared in the area. The sampling was discontinued when few <br />fish were being caught in the drift nets and when water temperature dropped <br />below 18 C. Sampling was conducted twice a weelc at various times of the day <br />and night. Each sample effort consisted of two nets each set for about 1 <br />hour. Seining and dip netting were also conducted during these sets to <br />complement information on species composition and fish development. During <br />the peak of drift activity, drift nets were set for about l-hour intervals <br />every 2 to 4 hours for a 24-hour period. Four drift nets were used at two <br />stations at the proposed intake. These nets were set in pairs, one stacked <br />atop the other to sample the surface water col urnn as well as the water <br />column immediately beneath. <br />The drift nets used were made of 560 micron mesh Nitex planlcton <br />netting. Each net had a rectangular opening of 12 x 18 inches and a length <br />of 9 feet which tapered to a removable collection cup. Each net was set <br />facing upstream with the top of the net even with the surface of the water, <br />except for those sets made during the 24-hour sampling, as described. Time <br />and water velocity were recorded for each drift net when set and retrieved <br />to enable computation of total water volume filtered and to provide <br />
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