7369

• UCREFRP Catalog Number: 7369
• Author: Marsh, P. C. and W. L. Minckley.
• Title: Radiotagging Razorback Suckers
• USFW Year: 1989.
• USFW - Doc Type: Gila River, Arizona 1988-1989.
• Copyright Material: NO

. ,

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Nine Implanted fish (Appendix Z), all in apparently good health, were
transpor~~d and released into the Gila River at the same site on 12
October t°88. Seven of these moved downstream an average of 8.1 km
(range O.i to 37.2 km) and remained viable for. an average of 39 d (range
i to 1~5); contact was lost with the other two fish shortly after
stocking. Stream channels occupied by fish (Table 1) averaged 10 + 3 m
wide. O.S ~ 0.4 m deep, and 0.30 ± 0.20 m/sec current velocity (n = 11).
Althoucn ~~elocity at contact locations was greater-than for fish stocked
in May :0.~1 ± 0.17 m/sec), the difference was not significant.
Radio-tracking was again conducted along al] ma,ior water delivery canals
and drains in the Safford Valley by truck, and throughout the Giia River
reach from San Jose diversion dam downstream to the delta at San Carlos
Reservoir by ail-terrain vehicle. No contacts were recorded.
In attempt to locate fish that were not contacted after stocking and
those with which contact was lost during the tracking period, San Carlos
Reservoi` was visited during early April 1989. It was determined that
radio-signal transmission distances were significantly-reduced as a
function of-water depth in the lake, i.g., a transmitter suspended 3 m
below sur`3ce could not be detected. and reception range at 1 m depth
was approximately 5 m. In contrast, straight-line detection distances
for dlffer~nt transmitters In-air ranged from ca. 50,to more than 150
Diminution of reception range In the lake may have been due to high
conductivity, which effectively attenuates radio signals, to
characteristics of our transmitters (e.g., age and battery condition>,
to condition of our radio recievers, unknown factors, or a combination
of these. Nonetheless, shallow shorelines and-deltaic areas of both
the Glta and San Carlos arms of the reservoir, Pius coves in vicinity
Coolidge Dam were thoroughly searched for signals for 3 d; none was
detected.
Individual tracking histories are In Appendix 2.
Relatively short periods of contact for fish released In October may
have been due to failure of transmitter batteries, most of which had
been activated for periods approaching their rated lifespans.
m.
of
In summary, radio-Lmplanted razorback suckers stocked Into the Gila
River exhibited short- and longterm downstream movements. Few fish
moved upstream. Similar results were obtained from studies of smaller.
Juvenile fish reintroduced to the Gila River. Habitats occupied by
located fish (Appendices i and 2) were primarily wide, sandy,'
mid-channel runs of modest depth and current velocity. Other fish were
in eddies or quiet backwaters or pools ad,lacent to main channel flows.
Data obtained during similar sttdies on Yampa and Green rivers, Colorado
and Utah, suggest simlar habitat. use. However, these upper basin
streams differ substantially in size and ether features from the Gila
River.
The uitfmate #ate of nine fish remains unknown. If dead. their
transmitters could have been buried so deeply In stream substrates as to