7152

• UCREFRP Catalog Number: 7152
• Author: Holden, P. B.
• Title: Relationship between Flows in the Yampa River and Success of Rare Fish Populations in the Green River System.
• USFW Year: 1980.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

7

By the time they reach about 8 inches, they feed almost totally on
fish (Vanicek and Kramer 1969). Adults live in a variety of habitats,
apparently changing their preferred habitat with the season.

-
The following analysis discusses the fishery data collected by

year, and compares it to the flow data, shown graphically, for that

year. Analysis of original fish data sheets were made so that all data
were analyzed similarly.

BID/WEST was contracted by the U.S. Fish and Wildlife Service in
1977 to conduct a study in the Green River below Jensen to determine
the habitat requirements of juvenile Colorado squawfish (Holden 1977).
In 1978 and 1979, BID/WEST sampled a station near Jensen in a Water and

Power Resources Service funded project to determine effects of inlet
modification of Flaming Gorge Dam (Holden and Crist 1978 and 1980).
In 1979, BID/WEST sampled a 20-mile section of river below Jensen for
a proposed power plant (Holden and Selby 1979). Therefore, a section

of the Green River between Jensen and Ouray, Utah, has been intensively

studied for three consecutive years, and excellent data on Colorado

squawfish reproductive success has been collected.
Table 1 summarizes the juvenile Colorado squawfish data for 1977-
79 by age class. Fish were assi9ned an age on the basis of lenqth/fre-
quency histograms for 1979, shown in Figure 2 (Holden and Selby 1979)
and those presented by Vanicek (1967) for 1964, 1965, and 1966. The

numbers of fish shown in Table 1 can be very misleading if the amount

of effort expended each year is not known. Durinq 1977 a thorough

seining survey was conducted of the entire river section between Jensen