7341

• UCREFRP Catalog Number: 7341
• Author: Valentine, J. J.
• Title: Hatchery and Laboratory Phase of the Colorado River Endangered Fishes Study.
• USFW Year: 1981.
• USFW - Doc Type: \
• Copyright Material: YES

Laboratories

The Utah Cooperative Fishery Research Unit, Utah State University
was selected to perform studies on the effects of temperature and
total dissolved solids and swimming performance of Colorado River fishes.
Their work began in December of 1979. The Idaho Cooperative at Moscow,
Idaho was selected to study the life history of both Northern and Colorado
squawfish, to develop certain cultural techniques and to perform
bioassays for selected chemicals on squawfish and the, humpback chub.
These projects began in April, 1980.

Temperature - Temperature preferance is. being determined under
laboratory conditions at USU for young-of-the-year, juveniles, and
subadults of the razorback suckers, Colorado squawfish, humpback chub
and bony tail chub hybrids. The fish are tested individually in either
an electronic shuttle box or a horizontal temperature gradient. They
are acclimated to temperatures of 14, 20 and 260 C. for a week or more
prior to testing.

The bow-tie shaped shuttle box contains a test fish in 15 gallons
of water and has intermittent inflows of hot and cold water from opposite
ends of the tank. Solenoid valves that control inflows are opened and
closed by photocells in the center that are triggered py the fish moving
back and forth. In effect, the fish selects the temperature water he
desires.

The horizontal gradient system establishes a broad range of tempera-
tures which the fish has to choose from within a tro~gh. The fish is
placed into the tank at its acclimation temperature and thereafter its
position is monitored releative to temperature. This system has been
used in lieu of the shuttle box for fish that were too small to activate
the photo cell mechanism. A smaller and a larger box are being built
for use with outsized fish.

Razorback suckers (l50-300mm) acclimated to temperatures of 20 and
260 C. were tested in the shuttle box. The final preferance for both was
22-230 C. based on 20 fish tested per acclimation temperature. Daylight
and dark preferances were 23 and 270 C., but were not significantly
different. Colorado squawfish about 100 mm in length, acclimated at
14, 20 and 260 C., had mean preferred temperatures of 20.3, 28.5 and
22.80 C. respectively, as determined in the horizontal temperature
gradient system. While the standard error for the razorback was 10
C., it was high as 3.30 C. for the squawfish. The humpback chubs and
bony tail hybrids will be tested in the near future.

Swimming Performance - For swimming performance studies a stamina
tunnel (Thomas, Burrows, Chenoweht, 1964) is being used to test indivi-
dual fish at three acclimation temperatures. Young-of-the-year or
juveniles, and subadults of the Colorado squawfish, humpback chub,
razorback suckers and bony tail chubs or hybrids are being tested.

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