7035

• UCREFRP Catalog Number: 7035
• Author: Cross, J. N.
• Title: Status of the Native Fish Fauna of the Moapa River ‎(Clark County, Nevada)‎
• USFW Year: 1976
• USFW - Doc Type: Transactions of the American Fisheries Society
• Copyright Material: YES

CROSS-MOAPA RIVER FISHES

505

TABLE 2.-Chemical analysis of the Moapa River, January 8-16, 1974. Stations 9' and 9" are located respec-
tively 0.8 and 2.0 km south of Station 9, All values are mg/liter unless otherwise indicated.

Stations
3 6 9 9' 9" 10
Turbidity (FTU) 0 10 32 15 17 20 10
Total dissolved solids 606 743 972 2,321 2,323 1,852 1,937
NO. 1.23 1.30 1.06 0,0 0.75 2.15 4.30
NO. 0.063 0,053 0.043 0.0 0.040 0.059 0.462
NH. 0,58 0.71 0.92 1.62 1.60 0.86 1.50
Total PO, 0.40 0.30 0.47 1.90 0.40 0.51 0.80
Ortbo PO, 0.26 0.10 0.15 0.17 0.13 0.15 0.50
Meta PO, 0.14 0.20 0.32 1.73 0.27 0.36 0.30
SO, 260 300 450 1,075 1,350 1,050 1,125
Cl 65 75 110 450 205 180 190
Total alkalinity (CaCO.) 220 260 260 500 380 200 260
NaCl 107 124 182 742 338 297 314
Mg 27 37 34 280 114 85 109
Ca 64 64 96 260 232 140 140
Hardness (CaCO.) 270 310 380 1,800 1,050 700 800
Chemical oxygen demand 90 40 35 2,300 20 35 45

(No.5). In 1974 4-liter water samples were
collected and analyzed according to the Amer-
ican Public Health Association (1965).
Fish were collected using a ll5-volt, 2,500-
watt AC shocker (Station 1 was collected with
tied seines in 1974). The lower end of each
station was blocked off with tied seines (3.7
m X 1.2 m X 6 mm mesh and 7.4 m X 1.2 m
X 6 mm mesh). Each station (except 9 in
1974) was collected with three consecutive
runs. All fish were identified, counted, re-
corded, and held in 22-liter buckets and re-
turned alive to the stream after sampling was
completed.

RESULTS AND DISCUSSION

Thirteen species of fish were collected from
the Moapa River (Table 3); four are native
to the river. Deacon and Bradley (1972)
listed 14 species from the Moapa River; of
these, Pimephales promelas (fathead minnow) ,
I ctalurus punctatus (channel catfish), and
Plagopterus argentissimus (woundfin) were
not collected during the 1974-75 study. No-
temigonus crysoleucas and Salmo gairdneri,
neither of which were recorded by Deacon
and Bradley (1972), were collected and con-
stitute new records for the Moapa River.

Fauna of the Headwaters

In 1963, prior to the introduction of Poe-
cilia mexicana (circa 1965), Gambltsia affinis
was the most abundant species in the head-

water springs; by 1968 P. mexicana was dom-
inant (Deacon and Bradley 1972). In 1975
Crenichthys baileyi comprised the majority
(60%) of the fishes collected (Table 4). Two
possible explanations for the shift in dom-
inance are suggested: (1) after an initial
increase, the P. mexicana population declined
followed by a resurgence of C. baileyi; and/or
(2) use of seines in the headwater springs
failed to yield a representative sample of the
fauna. The 1975 collection was made with an
AC shocker, previous collections were made
with tied seines. It was observed (1975) that

TABLE 3.-Phylogenetic listing of fishes collected in
the Moapa River (1974-75). Native species denoted
with an asterisk (*).

Salmonidae

Sa/mo gairdneri (rainbow trout)

Cyprinidae

Cyprinus carpio (carp)
Nntropi.v /utrensis (red shincr)
Gila rolmsta (roundtail chuh) *
Notemigofllls cry,,,'olcucas (golden shiner)
Rhinichthys o.,eu/us (speckled dace) *
Moapa coriacea (Moapa dace) *

lctaluridae

Icta/uTUs melas (hlack bullhead)

Cyprinodontidae

Crenichtl,ys bailcyi (White River springfish)'

Poeciliidae

Gambusia af/inis (mosquitofish)
Poccilia mer;caJUI (shortfin molly)

Centrarchidae

Micropten.., salmoil/es (Iar!!cmouth hlack bass)
Cllllcnobrytt... c1Janell... (!!reen sunfish).