8171

• UCREFRP Catalog Number: 8171
• Author: U.S. Fish and Wildlife Service.
• Title: A Study to Determine the Biological Feasibility of Pit Tags for Endangered Fishes in the Upper Colorado River Basin.
• USFW Year: 1990.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

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evaluated. The results will be included in a tagging study in progress at
Dexter NFH.
The number of fish recovered from the control and test groups from all of the
study ponds was low. Although the exact fate of the control and test fish in
the study ponds are unknown, we believe that the low number of recaptures
was not related to our inability to catch fish. The initial (48 h) mortality for
the control and test group fish was low. However, because fish were held for
only up to 48 h and then released, we were unable to further observe fish on a
routine basis and determine the extent of the delayed mortality that may have
been associated with the capture, handling, and tagging. The roundtail chub
used were wild riverine fish and their low survival may have been attributed to
their inability to adapt to a pond environment. The long-term mortality of
roundtail chub, razorback sucker, and Colorado squawfish in the control and
test groups in the pond studies was similar. Therefore, the factor(s) that
contributed to the demise of these fish probably affected all groups similarly.
This further leads us to believe that the capture and handling alone may have
contributed to the high long-term mortality.
In the field studies, the short-term performance of PIT tags was evaluated for
up to about 14 months. Because of the low number of fish recovered, only
limited data were obtained on PIT-tag retention, verification, placement, and
wound healing. Retention and verification of the presence and detection of
the tag was 100% for the two test groups.
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