7979

• UCREFRP Catalog Number: 7979
• Author: Tyus, H. M.
• Title: Fish Radiotelemetry
• USFW Year: 1982.
• USFW - Doc Type: Theory And Application For High Conductivity Rivers.
• Copyright Material: NO

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14
Sinning (1979) stated that discussions with other researchers were not
very helpful in evaluating the feasibility of using radiotelemetry in waters
with high conductivity. His professional contacts expressed doubt that radio-
. telemetry would be successful in rivers with conductivity exceeding 700 umhos.
Concern was also expressed about the propagation of radio waves in deep water.
Although the researchers thought it might be possible to track fish using
radiotelemetry, none of them believed that success could be guaranteed in the
Green River. Sinning (1979:22) concluded "...it is apparent that feasibility
of squawfish tracking in the Green River is not predictable with the present
state of knowledge...".
PRIOR RESEARCH IN THE GREEN RIVER
Although there have been attempts to use ultrasonic telemetry in the
Green River (McAda and Wydoski 1980), the only known attempt to use radio-
telemetry was by Holden and Shelby (1978). These authors surgically implanted
radio transmitters in seven Colorado squawfish. They were able to locate only
one fish, which was lost after 1.5 months. They stated that the main reason
for their lack of success was failure of the transmitters, causing (p. viii):
" ..weakening of signal strength over time, changes to frequency, and weakness
in initial strength."
Sinning (1979) evaluated Holden and Shelby's (1978) work and believed
that some of the problems encountered in the study were caused by use of
antennaless and long life (therefore low power) transmitters. Sinning (1979)
predicted a loss in radiated power of twofold due to the long life specifica-
tion and a loss of fivefold from the antennaless design. He adds that
(p. 23): ".., the transmitters used by Holden and Shelby likely produced no
more than 10 percent of the output that commercial transmitters would have
produced."
Holden and Shelby (1978) did not report water conductivity values. How-
ever, with the generally high (400 to 1000+ umho) conductivities in the Green
River, it is obvious that the transmitters used in the study were unsuitable,
particularly during periods when conductivities exceeded 600 umhos.
The problem of frequency drift that Holden and Shelby(1978) encountered
may have been related to transmitter design, because antennaless designs can
cause frequency variations. Sinning (1979) concluded (p. 24): "... it is
possible that some or all of the frequency drift observed ... was a result of
the antennaless design..."
It is unclear why all but one fish was lost immediately after release in
Holden and Shelby's study (1978). Based on the response of the one fish, it
apparently exhibited abnormal behavior. This behavior could have been caused
by the transmitter being too large for the fish or because the fish may not
have been held long enough before release for the incision to heal. A contin-
uous stitch was used instead of a series of discrete sutures. Failure of one
of the two knots could have caused a rupture of the sutured wound and death of
15