8061

• UCREFRP Catalog Number: 8061
• Author: Mueller, G. and P. Marsh.
• Title: Post-Stocking Dispersal, Habitat Use, and Behavioral Acclimation of Juvenile Razorback Suckers ‎(
• USFW Year: 1998.
• Copyright Material: NO

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Razorbacks possess a dorsal keel, which is pronounced in adults and less developed in young.
The keel of preserved speciemens loaned from the Arizona State University was examined as a
potential attachment site. Dissection indicated the keel was composed of a cartilagineous ridge
and a thin, poorly ossified bony plate. No major arteries, veins, or musculature were noted
suggesting external attachment to the fish's keel might be an alternative that might prove less
intrusive than surgical implants.

External sonic transmitters were attached to five razorback juveniles (32-35 cm TL) in Lake
Mohave during 1994. The attachment technique is similar to those used for Carlin tags, where
two sutures and a plastic backing plate held the transmitter in place (Stasko and Pincock 1977,
Winter et al. 1978, Matthews et al. 1990). We remained in contact with 4 fish, all successfully
carried the tags for the 45-day study.

The attachment technique was modified to a single suture and no backing plate to allow eventual
transmitter shedding and speed healing. Prior to attachment, a monofilament line about 30 cm in
length was positioned and glued to the center of each transmitter. The transmitter, line, and
needles were sanitized in a solution of alcohol and 10% betadine prior to attachment. Each
transmitter was activated and tested prior to attachment. Fish were weighed and measured and
then wrapped in a wet towel and placed in shallow plastic tub filled with water. The needle was
inserted about 6-8 mm below the fishes' dorsal keel. The ends of the lines were tightened over
the keel and tied with three square knots, and the fish was placed in a holding tank for transport
and release.

Twenty eight of the thirty Lake Powell transmitters functioned properly, one produced a weak
signal, and another had no signal at all. Fish processing and transmitter attachment was rapid,
typically taking less than a minute per fish. Groups of five fish were place within the blocked
coves (held) and on the lake side (free) of the blocking nets. Fifteen fish were held three days
and 13 were immediately released. The entire process took approximately 1.5 hours. Fish
exhibited no obvious stress nor was their swimming skill impaired. Water visibility was less
than 25 cm.

Blocking nets were removed 72 hours later and 5 suckers were found entangled in the net. Fish
were securely held and the mesh was cut to minimize stressing the fish. Fish were examined and
all sutures were still secure and wounds had not enlarged. One fish was released prior to
checking its transmitter code, the remaining fish were # 238, 436, 446, and 447.

Lake Mohave Smaller meshed blocking nets were used to reduce the chance of entanglement. A
group of 10 fish (5 held/5 released) was stocked at Owl Cove (RK45), 10 (5 held/5 released) at
Tequila Cove (RK32), and 7 at Mesa Cove (RK 29). We only tagged 7 at Mesa Cove because
we didn't want to use fish smaller than 21 cm. None of these fish were held for the acclimation
test. On May 23, the holding nets were removed. Only one fish remained in the Owl Point
holding cell and 2 in Tequila Cove, the other fish had already escaped.

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