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

the fish. Problems with transmitter size and transmission could have contrib-
uted to the loss of other fish.
Although Holden and Shelby (1978) encountered problems in their study,
their limited success 1n .using radiotelemetry in the Green River prompted
future investigations.
U.S. FISH AND WILDLIFE SERVICE FIELD STUDIES
Introduction
In March 1980, the U.S. Fish and Wildlife Service initiated a radio-
telemetry study of endangered fishes in the Green River in conjunction with
the Colorado River Fisheries Project (Miller et aT. 1981). Field operations
for the radiotelemetry study were directed from the FWS Field Station in
Vernal, Utah. More detailed information about this study is available in Tyus
et al. (1981).
It was evident from both a theoretical (Sinning 1979) and practical
standpoint (McAda and Wydoski 1980) that ultrasonic telemetry would not be
effective in monitoring movements of fishes in the Green River. However, the
limited success with radiotelemetry reported by Holden and Shelby (1978)
indicated that this technique might be effective.
Emphasis in this report is on radio reception from surgically implanted
transmitters in fishes in the natural environment, although some standardized
data obtained by immersing "naked" transmitters are reported. The study area
included the Green River from Jensen, Utah, to its confluence with the Colorado
River, over 482.7 km downstream. Within the area, the river flows through a
long stretch of whitewater in Desolation and Gray Canyons, has a relatively
high conductivity (ranging from about 200 to 1600 umho in 1980), and is full
of underwater objects and obstructions. The river, however, is quite shallow
through most of the study area, a factor that is important for success with
radiotelemetry.
Methods
FWS Colorado River Fishery Project personnel began testing radiotelemetry
equipment in the Green River in March, 1980. Field testing was done with AVM
and Smith-Root radio transmitters (fish modules) operating in the 40.660 to
40.700 MHz and 30.0 to 30.300 MHz range. The radio receivers were Smith-Root
search (SR-40) and standard tracking (RF-40) types. Larsen Kulrod NMO-40 whip
antennas and Smith-Root loop antennas were used. The field season ended in
September 1980 but limited testing was done as late as December to obtain
information on equipment performance in colder water (5° C).
After the project was initiated, only AVM fish modules (SM-i type) were
used for transmission. Transmission range was 40.660 to 40.700 MHz. The
module was powered by a mercury (Hg-630) battery and rated at a theoretical
life of 215 days, derived by dividing the battery capacity (14 milliamp-days)
by the expected current drain.(0.064 milliamps). The module weighed only
about 11 grams. Transmissions from the fish modules were pulsed at different
rates from about 60 to 90 counts per minute.
Radio transmitters were surgically implanted in the fish immediately
after capture. The fish were held in a 2.5 x 4 m ho}ding pert (Fig. 3) in the
Green River for one to two weeks after surgery The surgical procedure was
similar to Bidgood (1980) except that the incision was made on the lateral
aspect of the body wall, immediately anterior and dorsal to the insertion of
the right pelvic fin (Fig. 4), separate sutures were used, and knots were
coated with "Krazy glue".
Fish were located with the whip antenna mounted on a 20 cm2.piece of
0.5 cm thick flat steel plate, elevated about 4 m above the water surface on a
4 cm~ wooden post. All initial locating was done by boat or aircraft. Loop
antennas were used to triangulate fish positions at close range by boat and
from shore.
Aircraft were used throughout the study to locate fish. A Piper Super-
cub, operated by the U.S. Fish and Wildlife Service, Division of Animal Damage
Control, provided the best results because it could fly slowly at a low alti-
tude (100 km/h speed at 105 m altitude). The use of another airplane, flying
at about 150 kph, provided poor results. Two nmo-40 whip antennas were
attached to wing struts on the airplane and two receivers (a search and pin-
point type) were used with headphones.
Water conductivities (umho/cm) were measured with a Yellow Springs Model
33 Meter (not temperature compensated). Two meters were often tested together
to make sure they were operating correctly. Temperature readings from the
conductivity meter were verified by a handheld thermometer. Following the
American Public Health Association's (1971) Standard Methods text, conduc-
tivity readings were converted to the standard equivalent value at 25° C.
Six Colorado squawfish (TL 508 to 707 mm) and one razorback sucker
(TL 510 mm) were captured in April and May, surgically implanted with AVM fish
modules (SM-1) (Figs. 5 and 6), and released. These fish were tracked by
different methods until September, the conclusion of the 1980 study.
On December 18, 1980, two AVM transmitters (SM-i), one having a mercury
and one a lithium battery, and one Smith-Root small fish module were tested fn
the study area at different depths. A]] transmitters pulsed the signal at
about 60 counts-per-minute. Water conductivity was 480 pmho (770 umho
corrected to 25° C) and water temperatue was 5° C. All transmitters worked
satisfactorily. One transmitter (AVM No. 17010), which had earlier been
retrieved from Colorado squawfish No. 001, had been refrigerated. Receiving
antennas were about 4 m above the water surface.
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