3135

• UCREFRP Catalog Number: 3135
• Author: Wiltzius, W. J.
• Title: Some Factors Historically Affecting the Distribution and Abundance of Fishes in the Gunnison River
• USFW Year: 1978.
• USFW - Doc Type: Final Report for Fishery Investigations of the Lower Gunnison River Drainage.
• Copyright Material: NO

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sampler was placed over the stream bottom at depths not exceeding 2 ft.
The bottom rocks were hand rubbed allowing the stream flow to carry fauna
into the net of the Surber sampler. A total of 3 Surber samples was
procured from each station and all materials collected at a given sta-
tion and time were placed into a 1-qt jar and preserved with formaldehyde
for later examination. In the laboratory the insect fauna were usually
sorted to order designation using characteristics and/or keys presented
in Usinger (1956) and Edmonson (1959). Individuals from each order of
insects encountered were placed in plastic vials and for all orders
encountered except Coleoptera and Diptera the individuals were identi-
fied to genus and enumerated. Several Coleoptera larval forms were
encountered but only two, Optioserus and Narpus were positively identi-
fied to genus. No attempt was made to identify other Coleoptera indi-
viduals and they were enumerated as such. Members of the order Diptera
were identified and enumerated to the four families encountered viz.,
Tendipedidae, Simuliidae, Tipulidae and Rhagionidae. Only larval members
of the genus Atherix are known from the family Rhagionidae, hence the
use of the generic name rather than the family name. Non-insect inver-
tebrate fauna collected were enumerated to broad categories such as
snails, flatworms, clams, amphipods and annelids.
FISHERIES STUDIES
Fish Collections and Identification
During this study over 11,000 fish were collected by hook-and-line
fishing, shocking, seining, and standard 125-ft experimental gillnets.
The latter two methods captured most of the samples. Between 1973 and
1975, fish collections were emphasized in sections below the North Fork,