|
<br />I~.' ..,-io.'-'" "':'.' r: ~~~;.;,,.,_. ~~, .,,~.""::~'~"""''hIJ(f''lllniTiMfT Jm .'r~-q"'1!l~i~ir!,'liI 't. ." ~:. . . In lJl~'~' u';~fTl(;t'Jfl: ~ !t[:!
<br />
<br />..... 0' utala
<br />
<br />We lailltorle.
<br />
<br />III a chemical
<br />I been carried
<br />the only prac-
<br />Ipt a total kill.
<br />
<br />Deseription
<br />The two subspecies found in Utah are elongate, well-stream-
<br />lined fishes. They have expansive, strong fins, small scales, and a
<br />narrow caudal peduncle - features that enable them to resist swift
<br />currents. The least depth of the caudal peduncle enters the head
<br />length from 3.5 to 6.5 times. The back is often arched in the adult.
<br />The dorsal and anal fin rays vary from 8 to 11, usually 9 or 10;
<br />the dorsal fin originates behind the insertion of the pelvic fins. The
<br />scales number about 75 to 95 in the lateral line, and are often em-
<br />bedded in the skin or may be absent on the back and breast. The
<br />teeth are in two rows, with the formula 2,5-4,2. The young of this
<br />species and of Colorado squawfish (Ptychocheilus Lucius) are similar.
<br />In life the body is generally dusky to greenish on the back and
<br />upper sides, sometimes metallic blue, and silvery or white below;
<br />the axils of the paired fins and the base of the anal fin vary from
<br />yellowish. to reddish. The body is finely speckled over the back and
<br />sides. Breeding males are reddish on the sides of the head and
<br />~y, below the lateral line.
<br />
<br />Life History
<br />This species attains a rather large size for a minnow, up to
<br />nearly 17 inches in total length, but usually it is not much over
<br />8 to 13 inches long. A specimen 16.6 inches long weighed 1.2 pounds
<br />(McDonald and Dotson, 1960: 35).
<br />Spawning occurs in late spring to early. summer, as evidenced
<br />by the taking of ripe males and females of the bony tail on May
<br />31, 1950, in the Colorado River below Davis Dam, Nevada, and
<br />. of newborn young near Cottonwood Landing, Nevada, on June 15,
<br />1950. Breeding behavior was observed in Lake Mohave, Nevada,
<br />in May, 1954, with the aid of diving gear. An estimated 500 bony-
<br />tails were engaged in spawning on a gravelly shelf, each female
<br />apparently attended by three to five males. No nest was constructed,
<br />the eggs being broadcast and adhering to the rocks in water up to
<br />30 feet deep. Forty-two males and 21 females were recovered from
<br />the spawning area; they varied from 11 to 14 inche5y averaging about
<br />12 inches. A 12-inch female contained around 10,000 eggs, as esti-
<br />mated by the volumetric method. Each egg was about 1/32 inch
<br />in diameter and pasty-white.. No effort was made to protect the
<br />eggs by the spawning fish (Jonez and Sumner, 1954: 140-142). The
<br />postlarva was described and figured by Winn and Miller (1954).
<br />The Colorado chub is carnivorous, feeding largely on insects,
<br />crustaceans, and snails; however, filamentous algae are often present
<br />in the stomach.
<br />
<br />ail,
<br />
<br />
<br />to be of much
<br />Ierly eaten by
<br />where neither
<br />rtant 88 forage
<br />
<br />lIy and consti-
<br />lip.
<br />
<br />I
<br />
<br />.. to the Colo-
<br />. the River in
<br />III Colorado. It
<br />....llnun to be
<br />
<br />73
<br />
<br />~ '"",. c.. '.~..,.. )~~<::~~,~,"<. ,._ "'~'''''' ._y~ __.';'.
<br />
<br />"""" :"".'~""'''-':'''~~''":,,,"' ~.",",,- .~-' ~.. ,.,.., . . ". ,. "7"'c;'~"'~~'.""~';"7''':'''''''' .-- .
<br />
<br />"'
<br />
<br />~
<br />i
<br />t
<br />,
<br />
<br />t
<br />f
<br />
<br />~ ~
<br />
<br />.,~
<br />
<br />.~. ,
<br />
|