7268

• UCREFRP Catalog Number: 7268
• Author: Persons, W. R. and R. V. Bulkley
• Title: Feeding Activity and Spawning Time of Striped Bass in the Colorado River Inlet, Lake Powell, Utah
• USFW Year: 1982
• USFW - Doc Type: North American Journal of Fisheries Management
• Copyright Material: YES

shed daily
iddle, and
Ich depth.
wed for a
uiet water
tyon.Ich-
in 5-8%
;al dye for
sh eggs or
was esti-
of Green
, 188 km
discharge
co, Utah,
(Unpub-
vey, 1980
recorded
the river
(average,
ne period
rage 380)
I Canyon
X80 Sam-
he range
g striped
-9, May
temper.-
bove the
the 1981
fish Bot-
the 1981
of 1980.
)ed bass,
nnel cat-
lost fre-
00 hours
181 (Per-
he most-
:ommon
in 1981.
,ere cap-
A 10 in
Ind 6 in
,x .
STRIPED BASS IN LAKE POWELL
GYPSUM CANYON
--»1990
U 25 -1981
t, SPANISH BOTTOM
W - -1980
q: ---198I
20
cc
? 15
0" '
w 20
15
2
3: 10-
5
0
J
LL _
30 10 20 30 10 20 30 10 20
APRIL MAY JUNE JULY
Figure 1. Estimated flow (M3 /see) and surface-
water temperatures at sampling sites, 1980 and
1981.
Catches of striped bass during 1980 followed
the same general pattern as the surface-water
temperatures. There was a peak catch rate in
early May, a second in mid-May, and a third in
mid-June (Fig. 2). The catch during 1981 had
two peaks, one in early June and another in late
June. Other workers also have reported two to
four peaks In sr`awraa ng activity, ly
u possiba calre-
lated with rising temperature or falling water
levels (Hardy 1918).
Peak striped bass catches during 1981 exceeded
0.2 fish per gill-net hour, and the average catch
per unit of effort was 1.5 times greater than in
1980 (Fig. 2). The higher catch per unit of effort
during 1981 probably reflected the larger spawn-
ing population present in the headwaters because
of an additional year class reaching maturity.
Records indicated that the number of potential
brood stock fish (age IV or older) was 1.7 times
higher in 1981 than in 1980 (Gustaveson et al.
1981).
Although gill nets were fished on May 7-21,
1980, and May 26-June 2, 1981, near Spanish
Bottom, no striped bass were captured. Also no
bass eggs were observed in plankton tows. Thus
striped bass evidently did not move up through
Cataract Canyon rapids to spawn.
0
O_
X
tr
D
O
H
W
Z
2
U
r-
U
625
W
20
W
15
W
405
30 10 20 30 10 20 30 10 20
APRIL MAY JUNE JULY
Figure 2. Catch of striped bass (moving aver-
age of three) per gill-net hour (x100) and sur-
face-water temperatures at Gypsum Canyon,
1980 and 1981.
Four striped bass eggs were collected during
daily sampling with plankton nets in the Gypsum
Canyon area in 1980. One was collected in the
main channel of the river (river k-m 3 119") on June
9, another on June 17, and two more were col-
lected in a slow-moving water area of Gypsum
Canyon on June 16. The egg collected on June
17 evidently was not fertilized. It floated to the
surface of the sample and probably was dead.
The other three eggs were alive at the time of
capture and appeared to be in the early stages of
cell division. The size of the three fertilized eggs
was similar to those of a sample of fertilized
striped bass eggs taken in North Carolina (Man-
sueti 1958). No striped bass eggs or larvae were
collected during 1981 but sampling in late sum-
mer by Utah Division of Wildlife Resources per-
sonnel indicated good reproductive success in
the Colorado River inlet (Gustaveson et al. 1982).
Sex and Stage of Maturity
In most striped bass populations, males nor-
mally arrive on the spawning grounds before