7214

• UCREFRP Catalog Number: 7214
• Author: McAda, C. W. and R. S. Wydoski
• Title: Growth and Reproduction of the Flannelmouth Sucker,
• USFW Year: 1985
• Copyright Material: YES

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GROWTH AND REPRODUCTION OF THE FLANNELMOUTH SUCKER,
CATOSTOMUS LATIPINNIS, IN THE UPPER COLORADO RIVER BASIN, 1975-761
Charles W. McAda2,3 and Richard S. Wydos0,4
ABSTRACT.- Growth rates estimated using the scale annuli of flannelmouth sucker, Catostomus latipinnis, did not
differ between fish collected from the Gunnison and Colorado rivers, and the Green and Yampa rivers. However,
body condition and fecundity were significantly greater in the former population. Age of first maturity for male and
female fish from all rivers was IV; and most fish were mature by age VII. The smallest mature female collected was
405 mm, and the suallest mature male was 391 mm total length. Fecundity ranged from 4,000 ova in fish 450 mm
long to 40,000 ova in a 500-mm fish: mean ovum diameter was 2.39 mm. Ripe male flannelmouth suckers were
collected from early April through June; ripe females were collected from both study areas during May and early
June.
The flannelmouth sucker, Catostomus lati-
pinnis, is one of the most abundant and wide-
ly distributed native fishes in the warm "water
tributaries and mainstream rivers of the Up-
per Colorado River Basin (Tyus et al. 1982).
However, its distribution in the Lower Colo-
rado River Basin has been substantially re-
duced by habitat alteration resulting from
channelization and water development
(Minckley 1973). Despite its importance as a
native species endemic to the Colorado River
system, little is known of the biology of the
flannelmouth sucker (McDonald and Dotson
1960, Wiltzius 1976, Carlson et al. 1979). In
this report we describe the growth, maturity,
and fecundity of the flannelmouth sucker in
the major rivers of the Upper Colorado River
Basin.
METHODS
A#
O 1
Flannelmouth suckers were collected from
the confluence of the Yampa and Green riv-
ers in Dinosaur National Monument and
from reaches of the Colorado and Gunnison
rivers near their confluence in western Colo-
rado (Fig. 1). Descriptions of sampling sites
were provided by McAda and Wydoski
(1980), whereas an account of the general
physical and ecological features of the large
rivers of the Upper Colorado River Basin was
provided by Bishop and Porcella (1980).
Fish were sampled between April and No-
vember 1975 and 1976 by using trammel nets
(26-90 m long, 2.5 cm-mesh inner wall, 25
cm-mesh outerwall) and seines (30 m long,
2.5 cm mesh; and 5 m long, 3 mm mesh) and
by electrofishing. Collected fish were
weighed (g) and measured in total length
(mm). Scales from midway between the later-
al line and the anterior insertion of the dorsal
fin were used for age determination. An age
determination for an individual fish was con-
sidered to be accurate when agreement on
the number of scale annuli occurred between
the first and second examinations. A fish was
excluded from analyses that involved fish age
when no agreement on the number of scale
annuli could be reached after a third exam-
ination of the scales.
Total body length (TL, mm) at time of an-
nulus formation was estimated using the
equation TL = bo + b1SR + b2SR2 + b3SR3
(Carlander 1956), where SR is the radius to
that particular annulus x 80 and bo - b3 are
'The Utah Cooperative Fishery Research Unit is jointly supported by the United States Fish and Wildlife Service, Utah Division of Wildlife Resources,
and Utah State University.
'Utah Cooperative Fishery Research Unit, Utah State University, UMC-52, Logan, Utah 84322.
'Present address: United States Fish and Wildlife Service, 551 251A Road, Grand Junction, Colorado 81505.
'Present address: United States Fish and Wildlife Service, Program Plans, Washington, O,C: 20240.
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