9433

• UCREFRP Catalog Number: 9433
• Author: Anderson, R.
• Title: Riverine Fish Flow Investigations.
• USFW Year: 2002.
• USFW - Doc Type: Federal Aid Project F-288-R5,
• Copyright Material: NO

Three mark and recapture electrofishing passes were made at Sevens on the Yampa River
in 2001 on August 24 and 30, September 4 and mean daily flow on those dates (Maybell gage)
were 114 cfs, 70 cfs, and 64 cfs, respectively. Four passes were made for the entire station at
Duffy on August 21,23,28 and September 6 and flows on those dates were 105,98, 77, and 57
cfs, respectively. The upper deep run at Duffy, directly upstream of the launch site, were electro-
fished on August 20, and 27 at flows of 123 cfs, and 94 cfs, respectively. The Lily Park site was
electro-fished on August 22 and 29 and on September 5 at flows of91, 77 and 61 cfs recorded at
the Maybell gage. However, there is a USGS gage located on the Yampa River (above the Little
Snake), and this gage is located within lkm of the Lily Park study site. Flows recorded for
August 22,29 and September 5 from the Above Little Snake gage were 151, 110 and 96 cfs,
respectively and these flows should be used to represent this station. From now on, any
reference to mean daily flow for the Yampa River in regard to Lily Park will be from the Above
the Little Snake gage and corrections should be noted since Maybell gage reading were used in
2001 report.

On the Colorado River, fish in both study sites in the IS-Mile reach were marked to
designate the upper, middle and lower sections of the site in order to give a general idea of
movement within the station. In 1999, four electrofishing passes were made on the left half and
four on right side of the river. Sampling was modified in 2000 and the electrofishing boat
sampled twice along the right shoreline, left shoreline and mid river for a total of six passes in
each site. In 2001 the same sampling scheme was used as in 2000 and the number of polygons
was the same, 35 polygons on the Corn Lake site and 50 at Clifton. A total of sevens shocking
passes were made at both sites in 2001 with the additional pass in mid river. The additional pass
was found necessary to improve the standard error of the estimate. The dates and the mean daily
flow (cfs) for the Palisade gage on the day offish sampling at Corn Lake were 9/16 (701), 9/19
(915), 9/24 (857), 9/26 (859), 9/28 (790), 10/2 (715) and 10/4 (689). The dates and the flows
(cfs) of the fish sampling at the Clifton station were 9/20 (904), 9/21 (901),9/25 (891), 9/27
(824), 10/1 (735), 10/3 (684) and 10/9 (543). Fish from the Clifton site were given a unique
mark so they could be distinguished from fish marked downstream in the Corn Lake station.

The Dolores River was electro-fished in July 2001. On July 16, 17 and 18, block nets
were placed at the downstream end of each run (upstream ofriffies) and each run was
repetitively electro-fished three to five times. Fish from each pass were held in nets, then
marked and released into the same run of capture. This process was continued over the entire
reach. The entire study site was resampled on July 19 and 23. Block nets were not used on the
second and third samples made on July 19 and July 23. Summer flows are regulated by releases
from McPhee dam and flows generally vary between 65 and 80 cfs.

Habitat Maooin2

Global Positioning Systems and Sonar

In 1999 and 2000, bathymetric surveys of the channel were taken of the six study sites
using the Global Positioning Systems (GPS) and sonar technology. This technique, described in
the Anderson and Stewart (2000), is performed from a moving boat and gathers a large amount
of bathymetry data in a short amount of time. The GPS system used in this study was a Javad
Oddessy Ll/L2 RTK GPS with Glonass and Multi-path reduction options turned on. This

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