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f
<br />Two varieties occur within the Monument. The
<br />bonytail (G. robusta elegans) is so named because
<br />of the long and slender, pencil-shaped base to the
<br />tail fin, and the large fins have sickle-shaped bor-
<br />ders, to enable it to withstand swift current. The
<br />HUMPBACK CHUB, Gila cypha Miller
<br />This, the most remarkably specialized minnow in
<br />western North America and one of the most bizarre
<br />in the world, is known only from the Colorado River
<br />and its major, swift-flowing tributaries. It was first
<br />discovered in Grand.Canyon National Park in 1942;'
<br />since then it has been caught chiefly in the gorge
<br />sections of the Green and Yampa rivers in Utah and
<br />Colorado, and in that part of the Colorado River in
<br />Utah that lies above the junction with the Green
<br />River. The fish receives its common name from the
<br />abrupt hump that lies on the forepart of the back,
<br />just above the rear of the head. Its fins are even
<br />larger and more sickle-shaped than are those in the
<br />cotol
<br />COLORADO SQUAWFISH, Ptychocheilus lucius
<br />This predatory fish, also known as Colorado salmon
<br />and whitefish, is the largest minnow in North Amer-
<br />ica where it is native only to the Colorado River and
<br />its tributaries. In former days, when the species was
<br />more abundant, it was a valuable source of food for
<br />the Indians and early settlers, and it still puts up a
<br />good fight when hooked. Its importance now, how-
<br />ever, is as a zoological rarity, deserving of conser-
<br />vation as a unique part of our wildlife heritage. Its
<br />large size, well-streamlined, pike-like body, large
<br />head and mouth, and strong teeth (which lie back in
<br />the throat region, as in all minnows) adapt it well as
<br />a carnivorous predator. Carcasses of mice, birds, and
<br />small rabbits have been successfully used as bait
<br />roundtail (G. robusta robusta) lives in slower-moving
<br />water, its tail base is thicker, and the fins are small-
<br />er. In late spring and early summer, the breeding
<br />males of both varieties are reddish to salmon on the
<br />sides of the head and body. (see Paso 25 Top Illustration)
<br />bonytail, and the body is largely scaleless. All of
<br />these traits enable this chub to withstand the tor-
<br />rential flow-up to 18,000 cubic feet per second-of
<br />the swift sections of the river in which it lives. Water
<br />striking the elevated hump is believed to force the
<br />fish toward the bottom and help.it maintain resist-
<br />ance to flood waters. Adults reach a length of about
<br />16 inches. The young have not been identified and
<br />very little is known of the natural history of this ex-
<br />traordinary fish. Unfortunately, due to man's chang-
<br />ing the nature of the rivers it inhabits, it is becoming
<br />increasingly more scarce as habitat suitable for it
<br />continues to disappear. (see Page 25 Bottom Illustration)
<br />for catching large adults, as have also artificial lures.
<br />Very little is known of the life history. Specimens
<br />weighing between 40 and 50 pounds have been
<br />caught in the last 40 years and the species was
<br />reported to attain a weight of 80 pounds and a length
<br />of 5 feet or more before the turn of the century. Most
<br />individuals captured in recent years are between 4
<br />and 15 pounds; one taken below Flaming Gorge Dam
<br />in September, 1962, weighed 13 pounds and was
<br />nearly 3 feet long. The Colorado squawfish prefers
<br />big rivers, where the current is strong, the water
<br />muddy, and the depth is 3 or more feet; the young
<br />occur, however, where the current is moderate or
<br />slight and the water shallow.
<br />REDSIDE SHINER, Richardsonius balteatus (Richardson)
<br />This is a very common minnow in Utah west of
<br />the Wasatch Range and north of the Colorado River
<br />basin. It was introduced into the Wyoming part of
<br />the Green River in the 1930's, probably through use
<br />as a baitfish, and is now abundant as far down the
<br />Green as the Monument. The variety found in Utah,
<br />Wyoming, Colorado, and parts of Idaho and Nevada
<br />(R. balteatus hydrophlox), has fewer fin rays in the
<br />anal fin (the unpaired, ventrally located fin lying just
<br />before the tail or caudal fin) than the variety that is
<br />common throughout most of the Columbia River
<br />basin. The name "hydrophlox" means "waterflame,"
<br />in reference to the bright orange to red stripe on the
<br />sides of the body which is especially noteworthy on
<br />breeding males during the spawning season (April to
<br />July). The redside shiner does not grow longer than
<br />5 inches, and most individuals are about 3 inches
<br />long. It is a very hardy fish.
<br />26 NATURALIST
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