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Occasional Papers
Tulane University
Museum of Natural History
JUN 1 2 1995
I
The Humpback Chub,
Gila cypha, in the Grand Canyon Area of the
Colorado River
Royal D. Suttkus
Glenn H. Clemmer
Occasional Papers is published by Tulane University, N[usciim of Natural His-
tory. The Occasional Papers is dedicated primarily to Natural History: Sys-
tematics. Environmental Biology and Biogeography. The Occasional Papers will
appear irregularly in consecutively numbered issues. For information and policy
on exchanges, write to: Royal D. Suttkus, Director
Museum of Natural History
Tulane University
Belle Chasse, Louisiana 70037
When citing this publication, authors are requested to use the following: Occas.
Pap. Tulane U. Mus. Nat. Hist.
Cover photo: Mouth of the Little Colorado River in the Grand Canyon.
The National Fish and Wildlife Laboratory, Washington, D.C., supported pub-
lication of this number.
Printed by Drake Printers, Tuscaloosa, Alabama.
The Humpback Chub,
Gila cypha, in the Grand Canyon Area of the
Colorado River
roval d. suttkus
Glenn H. Clemmer
ABSTRACT
The humpback chub, Gila cypha, is redefined from specimens taken in the
Colorado River in the Grand Cianyon. Specimens from 24.6 - 320 mm are de-
picted, and notes on growth and development, sexual dimorphism, breeding
tubercles and coloration, and reproduction are presented with standard meristic
and morphometric data.
Editorial Committee for this paper: Dr. James E. Deacon, University of
Nevada at Las Vegas, Las Vegas, NV 89109.
Dr. James D. Williams, Office of Endangered Species, Fish and Wildlife Service.
Washington, D.C. 20240.
NUMBER 1, 1977
The Humpback Chub,
Gila cypha, in the Grand Canyon Area of the Colorado River
ROVAL D. SUTTKUS
Tulane University, Museum of Natural History
Belle Chasse, Louisiana 70037
Glenn H. Clemmer
Mississippi State University
Mississippi State, Mississippi 39762
Perhaps the earliest recorded observation of the hump-
back chub in the Grand Canyon is that of the Kolb
brothers (1914). Referring to a May trip (exact date
not given) , they heard a peculiar noise soon after lo-
cating their camp at the mouth of the Little Colorado
River. The following are quotations from their writing,
"Then Emery discovered what it was. On the opposite
side of the pool the fins and tails of numerous fish could
be seen above the water. The striking of their tails had
caused the noise we had heard. The "bony tail" were
spawning. We had hooks and lines in our packs, and
caught all we cared to use that evening". "They are
otherwise known as Gila Elegans, or Gila Trout, but
"bony tail" describes them very well. The Colorado is
full of them; so are many other muddy streams of the
Southwest. They seldom exceed 16 inches in length, and
are silvery white in color. With a small flat head some-
what like a pike, the body swells behind it to a large
hump."
The latter statement leads us to believe that they had
what is now known as the humpback chub, Gila cypha,
rather than what is presently known as the bonytail,
C.lla ek'garis.
Although the holotype of the humpback chub, (iila
cypha, was taken from the Colorado River near the
mouth of Bright .Angel Creek sometime prior to the fall
of 1942 (Miller, 1946) very few specimens have been
taken during the subsequent years. As recently as 1973,
Minckley made the following statement, ".\lmost nothing
is known of the biology of this [G(7(i cypha] fish, prin-
cipally because of the difficulties in collecting in its pre-
sumed habitat, and its resulting rarity in collections".
We began our study of the fishes of the Grand Canyon
area in 1970 and made 15 float trips by September 1976.
In the course of our studies we discovered a Gila cypha
population and have accumulated a significant amount
of biological information which is presented herein.
Methods and Materials
Methods of counting fin rays and scales and methods
of measuring follow those of Hubbs and Lagler (1964)
'Contribution Number 12. Tulane University, Museum of Natural
History.
with the following exceptions. The width of gape was
measured to the lateral side of the lips at the juncture
of the upper and lower lips. The middorsal head length
was measured from occiput forward to most anterior tip
of snout or upper lip. The pre-pelvic length was mea-
siued from insertion of left pelvic fin to most anterior
tip of snout or upper lip. The tip of chin to isthmus
measurement was made from the anteriormost tip of the
chin posteriorly to the posterior margin of the rugose
area at the "V" of the isthmus. The tip of snout to
isthmus measurement was made to the same posterior
point as the foregoing measurement. All measurements
were made with a dial calipers to the nearest 0.1 mm.
Our earlier collections from the Grand Canyon area
contained only young and juNcnile Gihi. In June of
1976 we were fortunate to obtain four adults from the
mouth of the Little Colorado River (Suttkus and Clem-
mer, in press) . Two adults, salvage specimens, were ob-
tained from Powell Reservoir. In addition we examined
specimens taken in 1967 from below Glen Canyon dam
and from Powell Reservoir. These latter two series of
specimens were formerly housed at Utah State Univer-
sity and recently have been transferred to the U.S. Na-
tional Fish and Wildlife Laboratory at Ft. Collins, Colo-
rado. Also we obtained four specimens on loan from the
Museum of Northern Arizona. Accurate measurements
were difficult or impossible on these latter three series
because of improper methods of preservation; thus some
dispersion of data on scattergrams is not true variability
but a reflection of inability to make accurate measure-
ments. Most specimens were distorted and twisted. Pre-
sumably Holden and Stalnaker in the removal of gill
arches from some specimens, removed and discarded both
left and right opercular elements so head length and
post-orbital measurements were not possible on these
specimens. Some fins (particularly the caudal) were dam-
aged or broken off, so no ineasurcments could be taken.
We did not estimate the measurement when the tip of
the fin was missing.
.Abbreviations for repositories of examined material
are: TU - Tulane University, Museum of Natural His-
tory, NFWL - National Fish and Wildlife Laboratory at
Ft. Collins, Colorado, and MNA - Museum of Northern
Arizona.
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
Identification
In view of Holden and Stalnaker's (1970, Table 2 and
Figure 4) remarks with regards to extensive 'intergiada-
tion' (their usage) in the Powell Reservoir area, we
postponed our identification of the young and juveniles
until we had sufficient materials for plotting scatter-
grams of various measurements. Authors in various
papers (Miller, 1946; Gaufin, Smith and Dotson, 1960;
Miller and Lowe, 1964; Holden and Stalnaker, 1970; and
Minckley, 1973) have mentioned or emphasized the
nuchal himip as a distinguishing feature of the hump-
back chub. We now view the nuchal hump as a highly
variable character. The small eye, the inferior, nearly
horizontal mouth and the combination of several other
characters in addition to the hump has enabled us to
identify the juvenile and adult specimens from the
Grand Canyon area as Gila cypha.
Smith {in: Gaufin, Smith and Dotson, 1960) in the
annotated list of fishes of the Flaming Gorge Reservoir
Basin in reference to Gila cypha stated that, "Young
specimens are difficult to identify because of the lack of
development of the characteristic shapes of the nuchal
area and caudal peduncle and the overlap in fin ray
counts for the three types". Holden and Stalnaker (1970)
said that, "Since general body morphology is very differ-
ent between mature and immature fish, a minimum size
of 210 mm standard length was enforced for most fish
studied".
Confronted with these various stated difficulties, we
proceeded cautiously in our determinations. We decided
that the logical way to determine the identity of the
young and juveniles was to obtain a graded size series.
During the early part of our study we considered the
slim-bodied specimens to be elegans or hybrids, but as
we accumulated more material and became familiar with
the variability, we became more and more convinced
that we had a single, highly variable form. Our belief
was substantiated by our collection of juvenile Gila
elegans form, Gila cypha, and Gila robusta from the
Green River in Utah (Figure 9) . During the last few
collecting trips in the Grand Canyon we were selective
in our collections attempting to obtain the different
body types as well as to fill the gaps in the graded size
series. Our specimens range in standard length from 24.6
mm to 320 mm. The largest specimen is one of the sal-
vaged specimens from Powell Reservoir. We have suffi-
cient specimens ranging in size from 26.4 to 110 mm in
standard length (Figures 1 to 8) but none between 110
and 164 mm in standard length. All of these up to 110
mm and the 164 mm specimen were obtained with a
ten-foot seine. Another gap exists in our data between
the 164 mm specimen and the 204 mm. A series of photo-
graphs (Figures 10 to 17) illustrate the differences in
body shape of the various size fish.
Although we are primarily concerned with an analysis
of Gila cypha from the Grand Canyon area, we present
an illustration (Figure 9) of juvenile specimens of the
elegans form (upper) , cypha (middle) and robusta
(lower) . These three specimens are almost the same
length (77.5, 71.2, and 70.3 mm in standard length, re-
spectively) and thus are suitable for comparison. The
three specimens were collected from the Green River.
The elegans and cypha were taken from near the town
of Green River, Utah, and the robusta specimen was
taken from near the town of Jensen, Utah. Note the
relatively small eye of elegans and cypha versus the large
eye of robusta. The caudal peduncle is most slender in
elegans and deepest in robusta. The caudal fin lobes are
longest and most pointed in elegans and shortest and
rounded in robusta. The mouth is essentially terminal
in elegans and robusta and subterminal or inferior in
cypha. This brief comparison is presented as background
information for the review of the series of illustrated
growth stages (Figures 10 to 17) of Gila cypha from the
Grand Canyon area. These illustrations are arranged
starting with smallest (upper illustration in Figure 10)
and proceeding to the largest.
Figure 10 illustrates three small specimens of approxi-
mately 2.5 centimeters (upper) to three centimeters in
standard length. The subterminal mouth is apparent
even at this small size. Also the slight concave dip is
apparent in the profile of the head. These three speci-
mens exhibit relatively long pectoral and pelvic fins.
Figure 1 1 illustrates a transition from a nearly scale-
less condition (upper) to visible lateral scales (middle
and lower) . The upper specimen has relatively short
pectoral and pelvic fins. The middle and lower illustra-
tions show two different snout shapes. The former has
a rather blunt snout and a slightly curved outline from
end of snout to nape whereas the latter has a rather
hooked and pointed snout and the dorsal outline shows
a cephalic dip. Perhaps this latter form represents the
juvenile stage of the adult which has the extreme hooked
snout and prominently developed hump.
Figure 12 illustrates three different combinations of
morphological features. The upper specimen has a blunt
snout, long pectoral fins, and moderately deep body. The
middle specimen has a moderately sharp snout with a
cephalic dip, short pectoral fins and a rather slim body.
The lower specimen illustrates a moderately sharp-
snouted individual but lacks a marked cephalic dip. It
has a moderately deep body and moderate-length pec-
toral fins.
Figure \?> also illustrates three combinations of mor-
phological features. The upper specimen has a blunt
snout, very little cephalic dip, short pectoral fins and a
moderately deep body. The middle specimen illustrates
a slightly sharper snout than the upper specimen but has
about the same degree of cephalic depression. The pec-
toral fins are long and obviously extend beyond the in-
sertion of the pelvic fins. The body is less deep than the
upper specimen but is not considered as a slender form.
The lower fish has a sharper snout than either of the
above and shows more of a cephalic dip. The body is
moderately deep, and the pectoral fins are moderately
long.
NUMBER 1, 1977
Figure 14 illustrates the deepest bodied juvenile (low-
er) that we have from the Grand Canyon area. The
upper specimen shows a blunt snout, short pectoral fins
and a moderately deep body. The middle specimen has
a sharp snout, moderate cephalic dip, long pectoral fins
and a moderately deep body. The lower specimen has a
blunt snout, slightly less than a moderate cephalic dip,
extremely short pectoral fins and an extremely deep body
as mentioned above.
Figure 15, upper and middle specimens have a mod-
erate body depth and a relatively sharp snout. However,
they differ to some degree in sharpness of snout, hooking
of snout, and depth of cephalic dip. The reader should
note that the upper and middle illustrations are of speci-
mens that differ approximately five centimeters in stan-
dard length. Too, the lower specimen illustrates a speci-
men approximately twelve centimeters larger than the
middle individual. All illustrations in figures 10 through
14 are enlargements of young or juvenile specimens. The
upper two illustrations in Figure 15 are also enlarge-
ments of juvenile specimens, but the lower illustration
in Figure 15 is a reduction of the actual size of an adult
female specimen. The three specimens illustrated in Fig-
ure 16 and the two specimens illustrated in Figure 17
are adults. The authors had no adult specimens from
the Grand Canyon area that exhibited the extreme snout
and hump development which was illustrated by Miller
(1946) and by Minckley (1973).
Figure 16 illustrates three of the four adults taken
from the mouth of the Little Colorado River. The lower
illustration of Figure 15 is that of the fourth specimen
from the Little Colorado River taken in June 1976. The
head profiles are similar for all four. The upper illustra-
tion of Figure 16 is that of the male and the middle and
lower specimens are females as well as the lower speci-
men of Figure 15. The male specimen was illustrated in
color by Williams and Finnley (1977) . The pectoral
fins are proportionately shorter in the three females than
in the male. The male has small tubercles (pearl organs)
on the head, body and fins as described below.
Figure 17 illustrates the male and female salvaged
specimens from Powell Reservoir. Neither specimen
seems to be typical of Gila cypha in all respects, but we
do not suggest they are hybrids. We interpret the differ-
ences as being within the variation of the species. The
ventrally arched body of the male tends to negate the
height of the nuchal hump. However, the mouth is ven-
tral and the eye small. Although the arching tends to
pull the pectoral fins forward, in its appressed position,
it nearly reaches the insertion of the pelvic fins whereas
the pectoral of the female (lower illustration of Figure
17) is not as long proportionately and extends somewhat
short of the insertion of pel vies. The tuberculation of
both specimens is described below.
Based on the consistency of data presented in the
scattergrams, and our extensive comparisons of various
specimens, we conclude that all our material from the
Grand Canyon is referable to Gila cypha.
Growth and Development
The smallest specimen (24.6 mm SL) does not have
pectoral fin rays fully developed. Specimens up to 28
mm in standard length may not have a full complement
of pectoral fin rays. Lateral line scale development is
the reverse of that in some fishes. Instead of a posterior
to anterior development the first lateral line scales de-
velop in the anterior region. Lateral line scales were not
sufficiently developed to make a count on 34 of the 74
young ancl juveniles. Specimens under 30 mm in stan-
dard length have fewer than ten lateral line tubes or
grooves and no scales. Specimens from 30 to 35 mm have
up to 35 scales partially or entirely developed and up to
45 tubes developed. The full lateral line scale series is
not developed until a standard length of around 50 mm
is attained. Scale development above and below the
lateral line is also progiessive with age. Specimens from
50 to 100 mm in standard length vary in having a few
rows (four to six) below and (six to eight) above the
lateral line to seven to ten rows below and ten to twelve
rows above. The size and exposure of the scales decrease
dorsally and ventrally away from the lateral line. Thus
toward the back and belly in general the scales are
smaller and embedded. The largest specimens are com-
pletely scaled on the back, the breast and the belly.
Scales on the back are small, embedded and spaced to
some extent. The breast scales vary from small and em-
bedded to well developed; however, they are not as large
as lateral body scales. The belly scales are well developed.
The posterior scales in the lateral line at the base of
the caudal are nearly typical in shape, but anteriorly on
the narrow part of the peduncle, the lateral line scales
are very elongate. These elongate scales grade anteriorly
into scales of more typical shape which make up the an-
terior third to half of the lateral line row.
Meristic Characters and Measurements
Frequency distributions of fin rays, vertebrae and scale
counts are given in Table 1 and Table 2. Other authors
mentioned above have pointed out that fin-ray, scale and
vertebral counts are not diagnostic characters for the
humpback chub, Gila cypha. We present the data par-
tially for the sake of completeness and partially to enable
a comparison with additional samples from the same area
and particularly with samples from other areas. Miller
(1946) gave counts for two specimens. Gaufin, Smith
and Dotson (1960) had 15 specimens available, but fre-
quency tabulations of fin-ray counts were not presented.
Holden and Stalnaker (1970) gave range and mean
values for dorsal and anal fin-ray counts, number of
vertebrae and numlier of gill rakers for 16 specimens,
but did not present frequency tabulations. Minckley
(1973) presented usual fin-ray counts, and in the key,
gave the figure of more than 81 lateral-line scales, but
did not state number of specimens examined. Miller
(1946) gave lateral-line scale count of 77-80 in Table 2,
and we presume the two numbers (77 and 80) are the
counts of the two specimens. Tiie dorsal and anal fin-ray
4
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
counts presented in Table 1 show agreement with other
data by the various authors. Vertebral counts reported
by Holden and Stalnaker (1970) did not include the
Weberian complex (four vertebrae) , thus when four is
added to the counts presented in their Table 2 the range
in the count becomes 46-49 which is inclusive in our
counts (45-49) presented in Table 1.
In addition to the above counts we counted the prin-
cipal caudal rays and contrary to the coimt of 20 given
by Miller (1946) for the holotype, we found that 95 of
the 96 specimens had 19 caudal rays. The one atypical
count was 18.
The lateral line scale count was difficult to make on
some specimens, but even on those sjjecimens the accu-
racy is within plus or minus two scales. Many specimens
had undulations in the lateral line row of scales, particu-
larly in the anterior portion. On a few specimens the
lateral line row had displaced sections of one to several
scales.
Pharyngeal arches were removed from twenty speci-
mens to determine nature of dentition. Miller (1946)
gave the dental formula of the holotype as 2,5 — 4,1? He
said there may have been a second tooth in the minor
row on the right arch. Seventeen of the twenty specimens
we examined have the typical Gila dental formula of
2,5 — 4,2. One specimen has 2,5 — 4,1, another specimen
has 1,5 — 4,2, and the remaining specimen of the twenty
examined has 2,5 — 5,2. The extra tooth on the right
arch is somewhat medial and practically has a common
base with the upper tooth of the major row. There is a
possibility that the two specimens with the single tooth
in the minor row on the one side did have two teeth and
one was broken off without leaving a trace of a stump
or a socket. However, the count may be correct in that
some specimens have very slender, delicate teeth in the
minor row and it is conceivable that this may be an in-
dication of a reduction in number.
X-rays of the larger specimens revealed a two-cham-
bered swim bladder.
A review of the 24 scattergrams (Figures 1-8) of pro-
portional measurements indicates a linear relationship
of all proportions with the standard length. Some obser-
vations do not apjjear on the scattergrams because of
overlap, but all data for each proportion were used to
compute regression formulae.
Sexual Dimorphism
Some males have decidedly longer pectoral and pelvic
fins than most females; however, a few females have
rather long paired fins. The relative position, size and
shape of the tubular termination of the digestive tract
(outlined with ink on illustrations) and the luogcnital
papilla are quite different in the female and the male.
Figure 18 illustrates the anal region of an adult female,
and Figure 19 illustrates that of an adult male. The
tubular ending of the digestive tract of the female is long
and extended posteriorly (overlapping base of first anal
fin ray) so that the urogenital papilla is hidden under-
neath when viewing the ventral surface of the fish. In
tiie male the terminal tube of the digestive tract is not
nearly so long and the urogenital papilla (indicated by
arrow on illustration) projects ventrally so that its tip is
visible just beyond the termination of the digestive tract.
Tuberculation of males and females differ consider-
ably. The nuptial male has larger tubercles and more
areas of the fins and body are studded with tubercles
than on the nuptial female. One of the four adult speci-
mens (TU 97918) collected from the mouth of Little
C^olorado River during June of I97() has small breeding
tuijercles scattered over the tojs of the head, laterally to
the rim of the orbit and about half way ventrally on the
opercle. There is a progiessively decreasing number of
tubercles on the hump from the nape toward the origin
of the dorsal fin. Tubercles extend nearly two-thirds the
distance toward the dorsal fin. There are no tubercles
on the underside of head, about the lips nor below the
orbit on the snout or cheek. .Although the anteromedial
patches of scales in front of the bases of the pectoral fins
(breast patches) are de\eIoped with free posterior mar-
gins, there are none with developed tubercular ridges.
I'here are small tubercles developed on the upper surface
of the second, third and fourth pectoral fin rays and also
on the upper surface of the second, third, fourth and
fifth pelvic rays. We consider the above male fish to rep-
resent an early stage of nuptial development.
The salvage specimens (TU 100542) obtained from
Powell Reservoir were near spawning condition if not
actually spawning at the time of capture. The larger
specimen (Figure 17 lower) is a female (320 mm SL)
and the smaller (Figure 17 upper) a male (298 mm SL) .
Unfortunately we did not obtain the specimens until a
number of months after they had been captured on 5
June 1975. The specimens exhibited some breeding color
even after having been frozen and stored in a freezer.
The entire lower side below dark pigmentation of the
body of the male was orange. The bases of pectoral and
anal fins were orange. The cheek below the eye was
yellowish and the iris was pinkish-orange. The female
was light orange on the lower portion of the side and at
the base of the anal fin. The base of the pectoral fin
was cream color. These colors may have been brighter
at the time of capture.
The tubercles and thickened epidermal layer had
sloughed off various parts of the body of these two speci-
mens dining the delay in getting the specimens from the
field to the freezer and then subsequent freezing and
thawing. However, sufficient tuberculation remains to
allow a desaiption of the sexual dimorphism in this
character. The male has rather large tubercles scattered
over the entire head (Figures 20 and 21) and smaller
ones posteriorly on the hump to about two-thirds the
distance toward the origin of the dorsal fin. The thick-
ened epidermal layer is missing from part of this region,
and perhaps, tubercles were present all the way to the
dorsal fin. These predorsal tubercles arc not particularly
associated with the embedded scales but are scattered
over the sinface. Some tubercles occur over the scales
NUMBER 1, 1977
and others occur over inter-spaces between the scales.
This is also true of tlie distribution of predorsal tubercles
in the female. There are a few tubercles on the ventral
portion of the head of the male. There are a few on
the istlmius, rami or lower jaws, on the branchiostegals,
and a few on the ventral portion of gill membrane.
There are well developed tuberculate ridges on the ex-
posed margins of the scales of breast patches (Figure 22) .
There are elevated blunt points along these tuberculate
ridges as though a row of tubercles became fused at their
base. Tliere is a single row of tubercles on the posterior
upper margin of the first pectoral fin ray and double
rows proximally on the second, third, fourth, fifth and
sixth pectoral fin rays. As the rays branch distally the
rows of tubercles also Iiranch to some extent. There are
a few tubercles on the seventh, eiglnli, and ninth pectoral
fin rays. There are developed tubercles on second, third,
fourth and fifth pelvic fin rays. The number of tubercles
diminishes from the third to the fifth pelvic fin rays.
Because of the extensive lateral area of the body from
which the thickened epidermal layer has been lost
through handling, the precise extent of tuberculation on
the lateral scales cannot be ascertained. We assume there
was an elongate tubercidate area extending from the
humeral region posteriorly to the region below the mid-
dle of the dorsal fin. There are a few lateral line scales
with a few small tubercles along their exposed margins,
but no scales below the lateral line appear to have any
tubercles, thus the major portion of the tuberculate lat-
eral scales is in the intervening area between the lateral
line and the small embedded dorsal scales. The tubercles
are situated along the exposed margins of the scales and
are larger and more numerous on the anterior scales in
the described patch. The number of tubercles per scale
margin varies from one to seven.
The larger female taken with the male described above
also has some tuberculation. There are very small tuber-
cles on anterior pectoral fin rays but none on the pelvic
fin rays. The tuberculate ridges are developed on the
margins of the scales of the breast patches.
Three of the seven specimens of sample no. 76-11 ex-
amined from the July 25-26, 1967 collection obtained
from just below Glen Canyon Dam by Stalnaker, Camp-
bell, Holden, and ]oe Stone have some tuberculation.
These male specimens (metal strap tag nos. 2761, 2763,
and 2771) are presently housed at the Ft. Collins, Na-
tional Fish and Wildlife Laboratory. Specimen number
2761 has slightly developed tubercles on the second, third
and fourth pectoral fin rays. There were no tubercles
on the head or the pelvic fin rays. Specimen no. 2763
has moderately developed tubercles on the .second to fifth
pectoral fin rays and the second to fifth pelvic fin rays.
There are a few tubercles on the first ray of the right
pectoral fin and few tubercles on toj) of the head on the
interorbital area. Specimen no. 2771 has a few tubercles
on the second, third and fourth pectoral fin rays, none
on the pelvic rays, a few on the top of head, tip of the
snout and upper part of the opercle but none on the
breast patches of scales.
.\nother series (sample no. 67-12) taken from Powell
Reservoir during 1967 by Rod Stone and Kent Miller
does not have a precise date, but by placement between
sample no. 67-11 and sample no. 67-13 which was col-
lected a few days after the Glen Canyon Dam collection
(cited above), the implied date for sample no. 67-12 is
26 or 27 of July, 1967. The four male specimens (metal
tag nos. 2736, 2737, 2739, and 2741) examined had slight
to extensive tuberculation. The tuberculation was simi-
lar to that described above. Specimen no. 2737 has the
best development of breeding tubercles on the fins.
There is a single row on the first pectoral ray and a
single row proximally to four rows distally on the second
to the seventh pectoral ray. There are no tubercles on
the first pelvic ray. On the second to the sixth pelvic
ray there is a single row of tubercles proximally which
soon divides into two rows, one on each branch, and then
each of the two rows divide to form four rows and then
into eight rows near the distal tips of the rays. There are
a few extra tubercles suggesting the beginnings of divid-
ing into sixteen rows of tubercles at the very margin of
the fin. The breast patches of scales have tuberculate
ridges on their margins. There are approximately fifteen
diagonal rows of these tuberculate scales. There are rela-
tively larger tubercles scattered over the top of the head
and smaller ones extending posteriorly over the surface
of the hump. There is a progressive decrease in number
of tubercles, and they occiu' no farther than about two-
thirds the way toward the dorsal fin. Tubercles on the
head extend laterally and ventrally over the upper two-
thirds of the opercle and the upper third of the cheek.
There is a hiatus on the mid-cheek area. The scattering
of tubercles on the ventral surface of the head extends
laterally and dorsally on to the lower third of the cheek.
The male specimen with metal tag no. 2736 is not as
tuberculate on the fins as no. 2737 but has tubercles on
the margins of the lateral body scales. The number of
tubercles per scale ranges from one to five. This speci-
men has relatively large tubercles on the top of the head,
and the smaller tubercles extending over the hump are
scattered all the way to the dorsal fin. There are tuber-
cles on the upper lip, chin, rami of the lower jaws and
on the branchiostegals. The tuberculate ridges are de-
veloped on the scales of the breast patches. Three of the
five female specimens examined (metal tag nos 2734,
2735 and 2740) have tubercles. Small tubercles are scat-
tered over the top of the head and extend back over the
nuchal liinnp toward the dorsal fin. Some tubercles are
present on the pectoral fin rays and one specimen has
some tuberculate ridges developed on the breast patches
of scales. None of the females have any tubercles on the
ventral side of the head, on the pelvic fins or on the lat-
eral body scales.
Reproduction
The males with extensive tuberculation described
above seem to have fully developed testes. Of the five
females studied (metal tag nos. 2732, 2734, 2735, 2738,
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
and 2740) one specimen 267 mm SL (no. 2732) has only
small granular ova. The other four females with stan-
dard lengths of 283, 292, 297, and 305 mm have two size
groups of ova. Ten ova of the larger size group from
female no. 2734 measured, 1.3, (4) 1.4, (3) 1.5 and
(2) 1.6 mm in diameter. Ten ova from female no. 2736
measured (4) 1.4. (5) 1.5 and 1.6 mm in diameter. The
smaller size gioup of ova in female no. 2735 measured
(4) 1.0, (5) 1.1, 1.2 mm in diameter. This female had
no tubercles anywhere on the Ijody or the fins. Female
no. 2740 is 305 mm in SL and is the only female of the
five that has tuberculate ridges developed on the scales
of the breast patches. Ten of the larger ova measured
1.6. 1.7, 1.8, 1.9, (2) 2.0. (3) 2.1 and 2.2 mm in diameter.
Six ova of the smaller size group measured 0.9, (2) 1.1,
(2) 1.2, and 1.3 mm in diameter. The smaller ova ap-
peared to be very pale whereas the larger ova were
yellowish. We believe this female was probably ripe at
the time of capture.
Ten ova were removed from the 320 mm SL female
(TU 100542) and these measured 1.3, 1.4, (5) 1.5 and
(3) 1.6 mm in diameter.
We have no measurements of fresh, non-preserved ova.
thus all our measurements above reflect the shrinkage
that takes place as a result of preservation.
Spawning probably occurs during June and Jidy in
the Grand Canyon area. We presume that the 24.6 and
the two 24.7 mm in SL individuals taken on 22 Septem-
ber represent young-of-the-year.
The future of the humpback chub population in the
Grand Canyon area is questionable. Perhaps a coldwater
strain may persist in the vicinity of the Little Colorado
River. The extreme man-manipulated flow patterns of
the main Colorado River can only be viewed as detri-
mental to the survival of the species. During average to
maximimi releases from Glen Canyon Dam the volume
of extremely cold water is too great for the Little Colo-
rado River water to have much warming effect. If ex-
treme low flows are going to be maintained dining the
summer of 1977 (spawning time) . this may have a tem-
porary benefit in that the warmer Little Colorado River
water will elevate more extensively the temperature in
the main Colorado River. Undoubtedly the lower Little
Colorado River is the major spawning area for the sur-
viving population. We collected and released a single
adult Gila cypha at the mouth of Shinumo Creek. Dur-
ing all of our sampling at Shinumo a total of three young
Gila cypha were taken, therefore we assume this area to
be marginal as a spawning site primarily because of its
small size.
Material Examined
Precise collection sites for Powell Reservoir specimens
of Gila cypha are not known; some came from Kane
County, Utah, and some from Coconino County, Ari-
zona. All Grand Canyon specimens were taken in Coco-
nino County, Arizona.
Powell Reservoir: National Fish and Wildlife Labora-
tory (NFWL) (metal field tag nos. 2732, 2734, 2735,
2736, 2737, 2738, 2739, 2740, 2741), TU 100542. Colo-
rado River just below Glen Canyon Dam: National Fish
and Wildlife Laboratory (metal field tag nos. 2761, 2762,
2763, 2768, 2769. 2770, 2771) . Colorado River at Lee's
Ferry, River Mile 0: Museum of Northern Arizona,
MNA Z5.29. Colorado River, River Mile 31.5: MNA
Z5.30. Colorado River, River Mile 31.9: MNA Z5.31
and MNA Z5.32. Colorado River at River Mile 44: TU
92785. Mouth of Little Colorado River. River Mile 61.5:
TU 78682, 89793, 95166, 95767, 97592, 97918, 97966,
99078. Colorado River. River Mile 66: TU 99081. Colo-
rado River. River Mile 71: TU 95777, 97921, 97967,
99086. Mouth of Shinumo Creek, River Mile 108.7: TU
95784. 99092. Green River at town of Green River,
Grand Co., Utah: TU 99151.
Acknowledgments
We particularly would like to thank the Federal En-
dangered Species Office for issuing the senior author
permit no. PRT8-185-C, and Amendment No. 1 to per-
mit no. PRT8-185-C which enabled us to collect and
study the unique form, Gila cypha. Also we extend our
appreciation to Robert A. Jantzen, Arizona Game and
Fish De])aitment; Dean Spackman, Utah Division of
Wildlife Resources; Merle E. Stitts, Grand Canyon Na-
tional Park and Joe L. Kennedy, Glen Canyon National
Recreation Area for the issuance of collecting permits
and for their cooperation. We thank Joe Kennedy for
the two salvage specimens from Powell Reservoir, and
we thank Steve Carothers for the loan of four specimens
housed at the Museum of Northern Arizona. Special ac-
knowledgment is due Clyde Jones and Robert Finley for
making available the specimens housed at the National
Fish and Wildlife Laboratory in Ft. Collins, Colorado.
We wish to acknowledge the help of Scott Thybony for
bringing our attention to the article by the Kolb broth-
ers. We also extend our deep appreciation to those who
helped us collect the material, namely: Lyn Branch,
Cindy Deacon, James Deacon. Robert Fisher, Jim Hall,
Clyde Jones, Linda Loetterle. Margaret Mathews, Dawn
Remington, C. Robert Shoop, Jayson Suttkus, and James
Williams. Jeanne Suttkus did the photographic work of
specimens for which we are most appreciative. The cover
photograph of the mouth of the Little Colorado River
was contributed by Robert Esher. W'ilma Martin did the
final drafting and photographing of the scatterg^ams.
This study was in part supported by National Park Ser-
vice Contract number CX82 1060006.
Literature Cited
Gaufin. A. R„ C. R. Smith and P. Dotson. I960. Aquatic survey of
the Green River and tributaries with the Flaming Gorge basin.
In: Ecological studies of the flora and fauna of Flaming Gorge
Reservoir basin. I'tah and Wyoming. C. E. Dibble, ed., LIniv.
Utah Anthropol. Pap. (48): 139-162.
Holden. P. B. and C. R. Stalnaker. 1970. Systematic studies of the
cyprinid genus Gila, in the I'pper Colorado River Basin. Copeia,
1970(3) : 409-420.
NUMBER 1, 1977
Huhhs, C. L. and K. F. Lagler. 1964 (reprint of 1958 ed.) . Fishes
of the Great Lakes region. Cranbrook Inst. .Sci. Bull. 2fi, 213 pp.
Kolb, Ellsworth and Emery Kolb. 1914. Experience in the Grand
Canyon. The National Geographic Magazine, 26(2): 99-184.
Miller, R. R. 1946. Gila cypha a remarkable new species of cyprinid
fish from the Lower Colorado River Ijasin, .\rizona. Jour. Wash-
ington Acad. Sci., 36: 409-415.
Miller, R. R. and C. H. Lowe. 1964. .\n annotated checklist of the
fishes of .\rizona. In: The vertebrates of .Arizona. C. H. Lowe,
ed.: 133-151. Univ. Arizona Press, Tucson, Ariz.
Mincklev, W. L. 1973. The fishes of Arizona. Arizona Game and
Fish Dept.. Phoenix. 293 pp.
Suttkus, R. D. and G. H. Clemmer. (in press) . Fishes of the Colo-
rado River in Grand Canyon National Park.
Williams, J. D. and D. K. Finnley. 1977. Our vanishing fishes: can
they be saved? Frontiers, 41(4): 21-32.
TULANE LNIVFRSITY MUSEUM NATLTIAL HISTORY
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10
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
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NUMBER 1, 1977
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12
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
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NUMBER 1, 1977
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FIGURE 5. Allometric growth in Gila cypha from Grand Canyon area of Colorado River.
14
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
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NUMBER 1, 1977
15
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FIGURE 7. Allometric growth in Gila cyplia from Grand Canyon area of Colorado River.
16
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
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FIGURE 8. Allometric growth in Gila cypha from Grand Canyon area of Colorado River.
NUMBER 1, 1977
17
■■m..
FIGURE 9 - upper
middle
lower
CAla clegans
Cwila cypha
(ilia robnsia
TU 101404
TU 99151
TU 99135
77.5 mm SL
71.2 mm SL
70.3 mm SL
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
FIGURE 10 - Gila cypha upper - TU 95166
middle - TU 95166
lower - TU 95166
26.5 mm SL
30.0 mm SL
34.2 mm SL
NUMBER I, 1977
19
FIGURE 11 - Gila cypha upper - TU 95777
middle - TU 97592
lower - TU 97592
40.8 mm SL
56.6 mm SL
65.2 mm SL
20
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
FIGURE 12
Gila cypha upper
middle
lower
TU 99078
TU 78682
TU 99078
69.6 mm SL
80.3 mm SL
82.5 mm SL
NUMBER 1, 1977
21
FIGURE 13
Gila cypha iijjpei
middle
lower
TU 99078
TU 99078
TU 99078
87.1 mm SL
89.9 mm SL
92.1 mm SL
22
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
FIGURE 14
Gila cypha upper
middle
lower
TU 95772
TU 99078
TU 95772
94.4 mm SL
95.6 mm SL
107.0 mm SL
NUMBER 1, 1977
23
'<^
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FIGURE 15
Gila cypha upper
middle
lower
TU 95767
TU 99078
TU 97918
110 mm SL
164 mm SL
253 mm SL, adult
9
24
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
FIGURE 16
Gila cypha upper
middle
lower
TU 97918
TU 97918
TU 97918
285 mm SL, adult
300 mm SL. adult Q
307 mm SL, adult -
6
9
9
NUMBER 1, 1977
25
FIGURE 17 - Gila cypha upper - TU 100542:
lower - TU 100542:
298 mm SL, adult O"
320 mm SL, adult Q
26
TULANE INIVFRSITY MUSEUM NATURAL HISTORY
18
FIGURE 18 - Gila cypha TU 100542: adult Q, anal region
NUMBER I, 1977
27
19
FIGURE 19 - Gila cypha TU 100542: adultQ, anal region
28
TULANF, UNIVERSITY MUSEUM NATURAL HISTORY
.^j*'
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20
FIGURE 20 - Gila cypha TU 100542: adult (j, dorsal view of head
NUMBER 1, 1977
29
21
FIGURE 21 - Gila cypha TU 100542: adultO, lateral view of head
30
TULANE UNIVERSITY MUSEUM NATURAL HISTORY
FIGURE 22 - Gila cypha TU 100542; adult(3, ventral part of head and breast
Harvard MCZ Library
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