7112

• UCREFRP Catalog Number: 7112
• Author: Minckley, C. O.
• Title: Fishes of Arizona.
• USFW Year: 1973.
• USFW - Doc Type: Arizona State University,
• Copyright Material: YES

123
t
boulders beneath the swarm were cleaned, presumably by current created
by the moving bodies, while those in other places were covered by sedi- ~,
ment. Females swam alone, peripheral to the swarm of males. When a
chased her as she accelerated
uall
l
y
es us
female moved near, 2 to 3 ma
to an open area, attempting to maintain position with their snout neap
ttom
b
h ;,
~-
,
o
e
the female's vent. A female followed by males dipped near t
and spawned with vibratory,
ved her back
i
,
ce, recur
usually over a crev
lateral movements. Males moved over and about her in a "solid mass;'
mber of"eggs was released at
ll
A
nu
presumably emitting sperm. Only a sma
female must have performed the act repeatedly to deplete her
i
me, so a
a t
The eggs adhered to the substrate (as has been noted in other spe-
ovaries
.
cies); however, none was found on the upper surfaces of stones. Unpro-
tected eggs were likely eaten by predators.
Young of P. luciusappeared in August in all three years that Vanicek

6 weeks after
3 t
F
o
& Kramer (1969) studied the Green River population,
Growth of the young fish continued
nin
f
g.
spaw
the estimated time o
throughout the year, and by the end of their third summer juveniles were
ecimen taken by
est s
lar
Th
h
p
g
e
.
averaging about 160 mm in total lengt
them was 600 mm total length, about 1.85 kg in weight, and was 11 '
~.
'years of age.
Foods of Colorado River squawfish in the Green River consisted of
hen the fish were shorter than
l
-
arvae w
crustaceans and aquatic dipteran
50 mm total length. An increasing number of aquatic insects, plus terrestrial r
insects, was taken when the fish were between 50 and 100 mm, and other
diet of specimens longer than 101 mm. There
d th
i
e
nate
fishes predom
was an increasing incidence of empty stomachs in #arger fish, reflecting
perhaps the sporadic nature of feeding often found in piscivores. Large
wn to take carcasses of small animals
k
b
no
een
adults of P. Lucius have
1963), and they also have been caught on artificial
and birds (Beckman
,
lures (as has P. grandis; Taft & Murphy, 1950). Relatively complete studies
man & Ouistorff (1938) and
f Cha
h
p
ose o
of foods of other squawfish are t
aft
d notes of
i
(
p
T
s, an
Thompson (1959) for P. oregonens
often
are
S Yder
for P. grandis. The last two species, and P. umpq
uts and sal-
t
ro
thought to be severe competitors of, and predators upon,
ive research for eradication and
i
t
ens
n
mons, and have been subject to
ol in areas where they are abundant (references already cited, and
t
con
r
MacPhee & Ruelle, 1969). It is notable that the oi~her three species of
squawfishes appear to be maintaining populations in their native ranges,
whereas P. Lucius is declining; the reasons for this are unknown.
As has been repeatedly implied, Colorado River squawfish, and
-river fishes, characteristic of
re bi
g
most other species of this genus, a
waters deeper than a meter and generally with stn~ng to mocerate cur-
rents. Young frequent backwaters over almost any bottom type, where
curren#s are slight or absent.
Gerhart (1950), Miller (in e S c~
mm )9 and ~numberoof ~ ther1Z'old
o
Game and Fish Department (p
,.