7125 ‎(2)‎

• UCREFRP Catalog Number: 7125
• Author: McAda, C. W.
• Title: Aspects of the Life History of Three Catostomids Native to the Upper Colorado River Basin.
• USFW Year: 1977.
• USFW - Doc Type: Utah State University,
• Copyright Material: YES

10
MATERIALS AND METHODS
Physical Parameters
Water temperatures were monitored at Echo Park and the Waiter
Walker Wildlife Area with a Ryan 30-day thermograph. Water temperatures
at other stations were taken with a pocket thermometer. Turbidities
were measured with a Jackson turbidimeter, and water velocities were
determined with a Gurley current meter.
Collection of Fish
Sampling of fish was conducted from April through November. Shelf
and floating ice prevented effective sampling during the winter months.
The majority of fish were collected with trammel nets varying in
length from 26 to 90 m, with an inside bar mesh of 2.5 cm and an outside
bar mesh of 25 cm. Suitable areas were sampled using a 30 m bag seine
with 2.5 cm mesh. In addition, small fish were captured using a 5 m
seine with 3 mm bar mesh. Swift, shallow water areas were sampled with
an electroshocker consisting of a 120 volt DC generator with a variable
voltage pulsator mounted on a 3.6 m aluminum boat. Electrofishing was
relatively ineffective during periods of high water because of swift
water-velocity and high turbidity. The efficiency of the trammel nets
was also reduced at these times due to large amounts of floating debris
and high water velocities.
Endangered or threatened fish were returned unharmed to the river,
although a few died from injuries suffered during capture. Dead