7124 ‎(2)‎

• UCREFRP Catalog Number: 7124
• Author: McAda, C. W. and R. S. Wydoski.
• Title: Technical Papers
• USFW Year: 1980.
• USFW - Doc Type: \
• Copyright Material: YES

11
During the present study, razorback suckers in
spawning condition were collected over gravel bars in
the Yampa and Colorado rivers. Three probable
spawning sites were located, although most razorback
suckers in spawning condition were collected from a
gravel bar in the Yampa River (station 3, Fig. 1),
400 m upstream from the mouth. The fish were col-
lected from water about 1 m deep, at the upstream end
of the bar. The substrate was predominantly- cobble
(stones 20 to 50 mm in diameter) and the water veloc-
ity was about 1 m/s (Table 9): During a 2-week period
in May 1975, 14 razorback suckers 12 females and 12
males) were captured over this bar. Females captured
in nearby locations were not yet ripe, but those col-
lected over the bar were ripe, indicating that they were
spawning in the immediate vicinity. All males cap-
tured over or near the bar were ripe.
Table 9. Physical characteristics of water at a spawn-
ing site in the Yampa River used by razorback
suckers, May 1975.
Date Temperature Velocity Depth Turbidity
(May) (°C) (m/s) (m) (JTU)
1 7 0.92 0.8 -
3 12 0.92 0.8 350
11 15 0.92 0.8 500
14 16 0.89 1.0 700
19 10 0.95 0.7 2,000
Spawning may have been attempted in the gravel pit
at station 8. Two ripe females and five ripe males were
captured at the west end of the pond in one trammel
net set overnight. These fish may have been swimming
along the shoreline during spawning, as described by
Douglas (1952). The shoreline was composed of cobble
(similar to the bars in the main river) and was regularly
agitated by wave action. Temperatures were near
17 C, and turbidities were about 100 Jackson turbidity
units (JTU-. No evidence of successful reproduction of
any native fish was found in the gravel pit during
1975. This apparent failure may be attributable, at
least in part, to the presence of sizable numbers of
introduced predaceous fish, such as largemouth bass
(Micropterus salmoides-, channel catfish (Ictalurus
punctatus), and green sunfish.
Movement
Movement Traced with Ultrasonic Transmitters
We inserted ultrasonic transmitters (cylinders
64 mm long, 16 mm in diameter, and weighing 19.3 g)
into the body cavities of one female and seven male,
razorback suckers. Surgical procedures were similar to
those used by Hart and Summerfelt (1975). Fish were
anesthetized with a synergic mixture of MS-222 and
quinaldine (Schoettger and Steucke 1970-. When a fish
became quiet, it was removed from the anesthetic and
placed on a V-shaped board. A 30- to 40-mm incision
was made in the ventral surface anterior to the pelvic
girdle and left of the median line. The incision was
placed to the side of the abdomen so the transmitter
would not rest on the stitches IC. D. Ziebell, personal
communication). The transmitter was placed in 70%
ethanol before insertion to sterilize the instrument.
Ethanol was also used to wash the wound at the com-
pletion of the operation and to sterilize the surgical
tools. No antibiotic was administered. The wound was
then closed with No. 000 surgical silk. This material
dissolved during healing. The gills were periodically
bathed with a dilute anesthetic solution during the 7 to
10 min required to complete the operation.
Postoperative care consisted of holding the fish until
it recovered from the anesthetic. Three fish were held
for several days to follow their recovery and observe
their ability to swim. To reduce handling stress, we
released the five other fish as soon as they had fully
recovered from the anesthetic and could swim well.
The transmitters were operated at 157.5 to 180.5
kHz. Each transmitter operated on a different fre-
quency, to enable identification of individual fish.
Tracking equipment consisted of abattery-powered
multifrequency receiver with headphones and a direc-
tional hydrophone. Fish movements were monitored
from shore or from a small boat. Effective range was
shorter than that reported by other investigators
(Hasler et al. 1969; Stasko et al. 1976; Ziebell 1973-; it
varied from 150 m in quiet water to only 10 m in turbu-
lent or rapid water. Fish locations were determined by
triangulation or by estimating the distance from a
single receiver by the strength of the signal.
In October 1974 and April 1975, three razorback
suckers lone female and two males) from the gravel pit
at station 8 (Walker Wildlife Area) were tagged with
ultrasonic transmitters. The primary reason for
tagging these fish was to familiarize ourselves with
surgical techniques and the ultrasonic equipment.
Also, movements were monitored to obtain infor-
mation on daily activity patterns.
The female was tagged on 29 October 1974, and fol-
lowed for 3 days to determine- its activities during a
24-h period. The fish was most active in late evening
(1900-2200) and late morning (1000-1200-. It remained
in the deeper end 13 m) of the pond during most of the
tracking periods, but moved into the shallow eastern
section of the pond during early morning (0100-0600).
The water temperature and bottom type were uniform
throughout the gravel pit and probably did not influ-
ence the movements. The bottom in the shallow water