9432 ‎(2)‎

• UCREFRP Catalog Number: 9432
• Author: Modde, T. and M. Fuller.
• Title: Feasibility of Channel Catfish Reduction in the Lower Yampa River.
• USFW Year: 2002.
• USFW - Doc Type: Vernal.
• Copyright Material: NO

fish; this required a slight modification in surgical technique (Ross 1982; see
Appendix; Table C.I. for a detailed explanation of surgical and radiotag
implantation techniques). The MCFT-7A transmitter implanted in pikeminnow in
1996, 1997, and 1998, was 16 mm in diameter, 83 mm long, weighed approximately
29 grams (air weight), and had a guaranteed life expectancy of 260 days.
Pikeminnow found in the fish trap in 1997 and 1998 (mean TL=534 and 516 mm,
respectively) were much smaller than those pikeminnow captured in the river in
1996 and 1997 (mean TL=733 and 688 mm, respectively) that were implanted with the
larger 7-volt transmitter. The 7-volt transmitter was too large for the smaller
pikeminnow that used the passageway in 1997 and 1998. 'Consequently, a smaller
and lighter radio transmitter, the MCFT-3FM transmitter, was implanted in
pikeminnow that were collected in the fish trap in 1999. This transmitter was
11 mm in diameter, 59 mm long, and weighed about 10 grams (air weight), and had
a life expectancy of about 560 days.
Receivers. LOTEKO model SRX 400 receivers used to monitor movements of
transmitter-tagged fish were of two types. One was a field datalogger, version
W16 data processing and storage system. These receivers were used in conjunction
with a DSP unit and an antenna switcher to simultaneously and continuously scan
all aerial and underwater antenna and report signals from tagged pikeminnow.
This reduced scan delay time minimized the likelihood of missing several tagged
fish that might simultaneously occupy a location for a short time. Each
receiver, DSP, and antenna switcher was enclosed in a weather-proof container and
powered by a photovoltaic panel and 12-v deep cycle battery. These were deployed
at a remote, fixed land-based site to constantly monitor the presence and
movement of tagged fish within predetermined receiving zones. This surveillance
technique provided an automatic means of constantly and simultaneously monitoring
and storing unique codes of tagged fish.
One fixed datalogging station was deployed in June 1996 at the Redlands
passageway on the Gunnison River. This station consisted of seven different
antenna-receiving sites. Four were aerial sites and three were underwater dipole
sites within the passageway. Data recorded from these sites provided fish
position relative to a particular antenna. Two other SRX_400 datalogging
receivers were used concurrently at two other riverside locations on the Lower
Gunnison River downstream of the Redlands Dam (RM 2.2 and 1.4). Each of these
downstream stations was used in conjunction with two three-filament directional
antennas during 1996-1998. Two of the downstream stations were dismantled and
redeployed in 1999 upstream of the Redlands Dam, one at Whitewater (RM 15.3) and
the other further upstream at RM 33.7.
Data collected by the fixed, land-based receivers were automatically stored
in an internal memory in the receiver and were downloaded monthly to a notebook
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