2525

• UCREFRP Catalog Number: 2525
• Author: U.S. Fish and Wildlife Service.
• Title: 25th Annual Recovery Program Researchers' Meeting.
• USFW Year: 2004.
• USFW - Doc Type: Moab, Utah.
• Copyright Material: NO

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the LCR. Hoop net captures were dominated by speckled dace (94% of the total catch) in
addition to nonnative carp, fathead minnows, plains killifish, black bullhead and YOY
channel catfish. In spring 2004, monitoring will continue above Chute Falls to determine
retention following spring runoff events.
Effects of repeated handling on bonytail chub - preliminary results
Hilwig, Kara, Pamela J. Sponholtz', David Ward 2, and Craig Paukert3
1 USFWS, Arizona Fishery Resources Office; Arizona Game and Fish Department;
3Kansas State University Cooperative Research Unit.
Humpback chub are sampled in the Little Colorado River in Grand Canyon each year
during the spring and fall to obtain population estimates. Repeated capture and handling
of fish during monitoring or research activities may cause stress leading to reduced
growth and/or condition and eventual mortality. We used bonytail chub as a surrogate
species to assess the effects of repeated handling on growth, condition, and mortality of
humpback chub. We simulated handling procedures currently used for humpback chub in
the Little Colorado River. Using a 0.10-acre pond divided in half with a net into control
and experimental sides, we placed 160 PIT tagged bonytail chub into each side. Fish
were sampled with hoop nets with two sampling trips in the fall and will be sampled
again in spring 2004. We measured fish length and weight and recorded the time required
to complete all steps for processing individual fish during two 3-day sampling events.
Preliminary results from fall sampling indicate handled fish did not gain as much weight
as non-handled fish however no differences in fork length were observed. Fish were
handled for a mean total time of 4.21 minutes that included removing fish from nets,
length and weight measurements, visual inspection, scanning and insertion of PIT tags
and release back into the pond (includes time in bucket). Although handling fish is
essential in understanding population dynamics, researchers should seek to understand
the effects of handling on fish and try to minimize any harmful sampling practices.
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