<br />
<br />----'-150.
<br />
<br />, ,
<br />CALIFORNIA FISH' AND GA.ME
<br />
<br />Distri'butWnj Abundance. The rainbow trout is not native to the Co]o..
<br />'rado. However, the npper waters of thiS drainage have been stockPd
<br />:With rairibOwsfor ,many years. ReeentIy; fairly larg~ numbers ha'l"e
<br />been planted in the,.river just below Boulder Dam. For -a discussion of
<br />this fishery refer" to Moffett (1942). ,
<br />There have been several reports of rainbows taken much further
<br />downStream, i.e., in the area discussed in this article. A few are said to
<br />be taken regularly in winter about 12 miles above Needles and th~y are
<br />found occasionally at Topock according to Mr. James Brown of ~PPllles.
<br />(Oral communication of February 17, 1942,) :Mr. J. A. Dannpr of
<br />Needles Boat Landing told me (February 15, 1942) that a 16-inch rain.
<br />bow was taken in Lake Havasu in the late fall of 1941" Two 18-inch rain.
<br />.,.----~ bow:~ere reported caught in tbis reservofiin-the Witlter'ofi942 accord.
<br />ing to :Mr. Meadows of the United States Fish and Wildlife Service at
<br />Needles. (Oral communication of May 5, 1942.) ,The lowermost record
<br />known to the author was furnished by :Mr. W. C. Blewett in a letter of
<br />February 17, 1943. While fishing for catfish in lower Palo Verde Slough
<br />on January 29, 1943, :Mr. J. C. Bowen took a 16-inch rainbow" carrying
<br />two large layers of eggs." The head of this trout was sent to the author
<br />for verification of the identification. ..
<br />Obviously, the lower river is unsuitable for the establishment of a
<br />permanent population of trout. We may, however, exp~t continued
<br />records 01 occasional downstr~am migrants especially during the colder
<br />. 'seasons.
<br />
<br />Catostomidae. Suckers
<br />
<br />The only fishes known from the lower river which do not possess
<br />. toothed jaws are the suckers and minnows ( Cyprinidae). The mouth
<br />of the suckers is located on the underside of the head j the lips are thick,
<br />very protractile, and are covered with small fleshy projections,
<br />
<br />Humpback sucker, Xyra#cbno t",..a"... (Abbott)
<br />
<br />Local, Names. Humpback sucker j razorback sucker j camelback; buf.
<br />falo (T).
<br />
<br />Recognition Characters. The large sharp-edged hump rising imme.
<br />diately behind the low flattened head readily identifies thi~ fish.IS
<br />
<br />Distributionj Abundance. This unique native species is found only in
<br />the Colorado River drainage. In 1890, "It was found extremely ab~'
<br />dant at Yuma and at all points below as far as the Horseshoe Bend, alld,m
<br />Hardee's Colorado,-" according to Gilbert and Scofield (1898), Gnn.
<br />nell (1914) took it near Mellen (Topock), Arizona, in 1910 bll~ says
<br />nothing of its abundance. In 1916, Evermann (1916) says that I,t ~:~
<br />rather common in the Salton Sea. Coleman (1929) states that It 1.1
<br />reported as rather common" there. In recent years, Moffett (1942 an
<br />1943) has observed it a short distance below Boulder Dam and in Lake
<br />Mead but does not discuss its abundance at either plaee.
<br />
<br />_ 1AJ'ordan and Evermann (1896, p, 184) give the coloration a.s "plain olivace~u;-~
<br />Ellis (1914 p 31) says that the general color Is ". · · bluish gray to ol1vaceous tt'!
<br />dorsal color fading gradually to silverY white below." The following col?r ~~st:
<br />taken from the fresh specimens described in this report may. therefore, be of ~nt;"'ni<h
<br />dorsal surface of the body and head, and sides or head. lITey; sides of bod~ t\~~ gr~~
<br />with a distinct copperlsh cast; ventral surfaces of head and body yellow. ....
<br />or olive.
<br />
<br />
<br />- ~~~~~~~~~:r";'::;~~~-'~~-=-~ ~-. .----..---..--"--- ---~~- --:,.--:--:---:...:-:-----~.. --.----.-----------~-
<br />iY.HE.'T!SHERY OF THE LOWER COLORADO RIVER 151
<br />::::;/.:~:,:,-,-<----:
<br />r;;:-....._~' _~~ ,. ~
<br />.~:ftwaS most plentiful atone time throughout the lower
<br />;ii:tEi"agricultural ditches according to residents. It is now
<br />,i~'T'liisWasthe only native fresh-water species seen in: the
<br />,.author in 1942, and it was noted at only one point. On the
<br />.ay19th, a small school of humpbacks was seen in a bay
<br />'e''lIeadgate Rock Da.m near Parker. Attempts to surround
<br />'''''ewere unsuccessful, but an overnight gill-net set caught
<br />Thiee of these escaped, and six others were released after
<br />fShad been taken. The following information is based
<br />on the examination of these fish.
<br />
<br />~ijrthese fish averaged 16.4 inches in length (range, 13.4-20,8
<br />,', pollDdB-{range-;=I.l-:a:371'oUiiasYiri:--wergnf;='=-.r ordan
<br />'":' (:1896} state that this species reaches a weight of 8 to,lO
<br />
<br />.S~egonads of the 4 fish examined showed them to be
<br />,_~,!~!~ of the males which were released had flowing milt.
<br />
<br />~." tive tractsof 4 fish were examined. In each case the
<br />cCked with silt which was rich in microscopic organisms
<br />'" IDB) and filamentous algae~.. The gut is long, being
<br />',gthin a specimen 16.9 inches long. It seems probable
<br />,if of large quantities of. bottomBilt enables them to
<br />'~triment from its. organic.coI).Stituents. In this regard,
<br />'ofthehumpbacks'uckerare similar_to those of the
<br />~.::~.~,' . -, - -
<br />-,' -,
<br />
<br />
<br />.it1tery~' This sucker is not a game fish, and the author has
<br />9~:ll.S_to.its use as a foodfieh by the residents of the lower
<br />~14}- reports that it u,.. .. :jt'.:.---istaken incnumbers by
<br />...., . ':from the Colorado River near Fort Mohave," and
<br />orado) it is marketed along with the 1tannel-mouthed
<br />'tfbmus latipinnis).
<br />:':detritus is its primary source of food this species would
<br />t{)be=-ln direct competition with any other fish except the
<br />~tIJ.S probable that it is able to utilize much potential food
<br />"(i.otherwise go to waste. Furthermore, if young suckers are
<br />" 'efish; this species would thus serve as a valuable link in a
<br />:ind actually increase the productivity of the river.
<br />
<br />Cyprinidae. Minnows
<br />
<br />.~a the suckers (Catostomidae) are the only fishes found
<br />IlJ:Jilckteeth in their jaws. The mouth of the minnows has a
<br />%T~;tfr.terminal position (i,e., it is not located distinctly on the
<br />~Clfthehead), and the lips are not thick or covered with small
<br />"'_~c:>~ Some members of the minnow family reach a large
<br />
<br />,.::~~'
<br />CJUiracters. It is readily distinguished from all other
<br />;;~~rr: the river by: its long dorsal fin with a toothed spine;
<br />
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