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

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North American Journal of Fisheries Management 4:403-408, 1982
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Feeding Activity and Spawning Time of Striped Bass W1,90e
in the Colorado River Inlet, Lake Powell, Utah
W. R. PERSONS AND R. V. BULKLEY
Utah Cooperative Fishery Research Unit
Utah State University, UMC-52
Logan, Utah 84322
ABSTRACT
Striped bass, Morone saxatilis, from Lake Powell, Utah spawned in or near the mixing zone of
the reservoir and the Colorado River in 1980 and 1981. The fish did not move through Cataract
Canyon rapids just above the reservoir in either year. Of 321 adult striped bass stomachs examined,
30% contained food and 28% contained thread
fin shad, Dorasoma Qetenense. No stomachs con-
tained native threatened or endangered Colorado River fishes.
Striped bass, Morone saxatilis, is an anadro-
mous coastal species that has been successfully
established in a number of freshwater reservoirs
in the United States. The species was first intro-
duced into Lake Powell (Glen Canyon Reservoir)
on the Colorado River in 1974. Gustaveson et
al. (1980) reported that growth is rapid in the
reservoir, males mature at age II (length, 440
mm), and females at age IV (670 mm).
Striped bass move into estuaries and rivers to
spawn during spring and early summer. Spawn-
ing occurs at temperatures of 10-25 C but most
frequently at 15.6-17.8 C (Hardy 1978). Spawn-
ing is usually concentrated within the first 40 km
above salt water, but distance traveled by spawn-
ing fish in individual rivers is highly variable.
Spawning occurs primarily between river kilo-
meter 25 and 62 in the Hudson River (Rathjen
and Miller 1957) and about 209-217 km upriver
in the Roanoke River, North Carolina (Hardy
1978). In other streams, mature striped bass may
move as far as 320 km upstream from salt water
(Raney 1954). The species has spawned success-
fully in the headwaters of several reservoirs: San-
tee-Cooper Reservoir, South Carolina; Kerr Res-
ervoir, Virginia and North Carolina; and
Millerton Lake, California (Calhoun 1966). Con-
centrations of adult striped bass in the mouth of
the San Juan and Colorado rivers in recent years
suggested that Lake Powell striped bass were
spawning naturally. Gustaveson et al. (1981)
reported natural reproduction within the reser-
voir near Glen Canyon Dam.
Striped bass frequently spawn in turbulent,
muddy, silt-laden areas characterized by rapids,
boulders, and strong currents (Merriman 1937;
Raney 1952; Mansueti and Hollis 1963; Talbot
1966). For successful spawning, water current
should be sufficient to keep the semibuoyant eggs
from settling to the bottom, where they might
become silted over and smother (Bigelow and
Schroeder 1953). Only if eggs were not covered
with silt or exposed to low-quality water could
they survive on the bottom (Bayless 1967). Incu-
bation period of the drifting eggs is 48-72 hours
at 15.6-17.8 C (Talbot 1966).
In the upper Colorado River drainage, three
native fishes-Colorado squawfish (Ptychochei-
lus Lucius), humpback chub (Gila cypha), and
bonytaiI (Gila elegans)-are classified as endan-
gered; one species, the razorback sucker
(Xyrauchen texanus), is considered rare. Inas-
much as striped bass are highly piscivorous, a
concern existed as to whether or not the adult
spawners would prey on the native fishes during
the bass spawning migration in the river. Our
study was conducted to determine if striped bass
were moving into the Colorado River at the head
of Lake Powell to spawn and determine the stom-
ach contents of the migrating fish.
SAMPLING SITES
Two sampling sites were selected to monitor
striped bass in the Colorado River inlet-Gyp-
sum Canyon at the head of the reservoir and
Spanish Bottom just above Cataract Canyon rap-
ids. Gypsum Canyon (river km 317) is just below
the last rapid in Cataract Canyon and has a rel-
atively large expanse of calm water. During 1980,
when the river flow reached 1,800 m'/sec, the
river-reservoir mixing zone extended for several
kilometers below the lowest rapid. The main
channel area near Gypsum Canyon had rela-
tively strong currents and back eddies. The res-
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