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The bonytail chub or bonytail (''Gila elegans'') is a species of freshwater
ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...
belonging to the
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Leuciscidae Leuciscidae is a family of freshwater ray-finned fishes, formerly classified as a subfamily of the Cyprinidae, which contains the true minnows. Members of the Old World (OW) clade of minnows within this subfamily are known as European minnow ...
, which includes the daces, chubs, Eurasian minnows and related species. This fish is native to the
Colorado River The Colorado River () is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and in northern Mexico. The river, the List of longest rivers of the United States (by main stem), 5th longest in the United St ...
basin of
Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...
,
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
,
Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
,
New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...
,
Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
and
Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...
in the southwestern United States; it has been
extirpated Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions. Local extinctions mark a chan ...
from the part of the basin in Mexico. It was once abundant and widespread in the basin, its numbers and range have declined to the point where it has been listed as
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
since 1980 ( ESA) and 1986 (
IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
), a fate shared by the other large Colorado basin
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
fish species like the Colorado pikeminnow,
humpback chub The humpback chub (''Gila cypha'') is a Endangered species act, federally protected fish that lived originally in fast waters of the Colorado River system in the United States. This species takes its name from the prominent hump between the head ...
, and razorback sucker. It is now the rarest of the endemic big-river fishes of the Colorado River. There are 20 species in the genus '' Gila'', seven of which are found in Arizona.


Description

A bonytail chub can grow to long. Like many other
desert A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...
fishes, its coloring tends to be darker above and lighter below, serving as a
camouflage Camouflage is the use of any combination of materials, coloration, or illumination for concealment, either by making animals or objects hard to see, or by disguising them as something else. Examples include the leopard's spotted coat, the b ...
. Breeding males have red
fin A fin is a thin component or appendage attached to a larger body or structure. Fins typically function as foils that produce lift or thrust, or provide the ability to steer or stabilize motion while traveling in water, air, or other fluids. F ...
bases. They have a streamlined body and a terminal mouth. Bonytail chubs have bodies that sometimes arch into a smooth, predorsal hump (in adults). While their skull is quite concave, their caudal peduncle (tailside) is thin, and almost looks like a pencil (hence, "bony tail"). The coloration of bonytail chubs is usually dark dorsally and lighter ventrally, however, in very clear waters, they look almost black all over.Minckley, W.L. 1973. Fishes of Arizona. Arizona Game and Fish Department, Phoenix. pp. 95–96. During breeding season, males and females have distinct coloration as well. Mature males have bright red-orange lateral bands between their paired fins; while females have a more subdued coloration that is described with the males.


Range and status

The bonytail chub was once found in the
Colorado River The Colorado River () is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and in northern Mexico. The river, the List of longest rivers of the United States (by main stem), 5th longest in the United St ...
basin in many U.S. states, including
Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...
,
California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
,
Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...
,
Nevada Nevada ( ; ) is a landlocked state in the Western United States. It borders Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the seventh-most extensive, th ...
,
New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...
,
Utah Utah is a landlocked state in the Mountain states, Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico. It also borders Wyoming to the northea ...
and
Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...
. It also occurred in the part of the basin in Mexico, but it has been
extirpated Local extinction, also extirpation, is the termination of a species (or other taxon) in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinctions. Local extinctions mark a chan ...
from this country. This fish species experienced the most abrupt decline of any of the long-lived fishes native to the main-stems of the Colorado River system. No remaining wild population is self-sustaining and it is
functionally extinct Functional extinction is the extinction of a species or other taxon such that: #It disappears from the fossil record, or historic reports of its existence cease; #The reduced population no longer plays a significant role in ecosystem function; #T ...
. Its survival currently relies on release of
hatchery A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish, poultry or even turtles. It may be used for ''ex situ'' conservation purposes, i.e. to breed rare or endangered species under controlled ...
-produced fish; several hatcheries maintain this species. Bonytail chubs were one of the first fish species to reflect the changes that occurred in the Colorado River basin after the construction of
Hoover Dam The Hoover Dam is a concrete arch-gravity dam in the Black Canyon of the Colorado, Black Canyon of the Colorado River (U.S.), Colorado River, on the border between the U.S. states of Nevada and Arizona. Constructed between 1931 and 1936, d ...
; the fish was extirpated from the lower basin between 1926 and 1950.Mac, M. J., Opler, P. A., Haecker, C. E. P. and Doran, P. D., editors. 1998. Status and Trends of the Nation's Biological Resources - Southwest. United States Geological Survey, Biological Resources Division, 986 pp. They may still be found in the Green River of Utah and perhaps in the larger Colorado River water bodies. ''Gila elegans'' was added to the US list of endangered species on April 23, 1980 and was first recognized as
Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
in 1986 by
IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
. In 2013, its IUCN status was upgraded to
Critically Endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
. There is contention about the reintroduction of the bonytail chub. Some are concerned about the amount of water used to increase stream flows that are required for adequate bonytail chub habitat. Bass fishermen are concerned about facilitating the recovery of the bonytail chub by the removal of
smallmouth bass The smallmouth bass (''Micropterus dolomieu'') is a species of freshwater fish in the Centrarchidae, sunfish family (biology), family (Centrarchidae) of the order (biology), order Centrarchiformes. It is the type species of its genus ''Micropterus ...
, a popular gamefish. Fears of spreading the
quagga mussel The quagga mussel (''Dreissena bugensis'') is a species (or subspecies) of freshwater mussel, an aquatic bivalve mollusk in the family Dreissenidae. It has an average lifespan of 3 to 5 years. The species is indigenous to the Dnipro River dr ...
, an invasive species that clogs water pipelines and fouls marine equipment, has halted the reintroduction of the bonytail chub in Arizona, pending establishment of a stocking protocol that is satisfactory to Arizona wildlife officials.


Habitat

Bonytail chub prefer backwaters with rocky or muddy bottoms and flowing pools, although they have been reported in swiftly moving water. They are mostly restricted to rocky
canyons A canyon (; archaic British English spelling: ''cañon''), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency t ...
today but were historically abundant in the wide downstream sections of rivers.


Biology

Young bonytail chubs typically eat aquatic plants, while adults feed mostly on small fish, algae, plant debris, and terrestrial insects. Bonytail chubs are long-lived and may reach an age of up to 50 years.


Reproduction

Little is known about their reproductive habits, but they are thought to spawn in mid-summer and perhaps hybridize with both roundtail and
humpback chub The humpback chub (''Gila cypha'') is a Endangered species act, federally protected fish that lived originally in fast waters of the Colorado River system in the United States. This species takes its name from the prominent hump between the head ...
s. Spawning in
Lake Mohave Lake Mohave is a reservoir on the Colorado River between the Hoover Dam and Davis Dam in Cottonwood Valley (Arizona/Nevada), Cottonwood Valley defining the border between Nevada and Arizona in the United States. This stretch of the Colorado Rive ...
has been observed during May, while in the upper Green River, it occurs in the months of June and July. Eggs are laid randomly over the bottom, and no parental care occurs.


Conservation

The bonytail chub's population sizes are small, and continue to become even smaller. The depletion of the population is primarily due to the habitat alterations caused by dams and due to competition and predation by non-native fish. A USFWS Recovery Plan was established in 1990, and included objectives of protecting the habitats of the bonytail chub, and even reintroducing hatchery-reared fish into the wild.Bagley, B.E. 1989. Nongame field note: Bonytail Chub. Arizona Game and Fish Department, Phoenix. pp. 1–3. The Bonytail Chub Recovery Plan was approved on September 4, 1990, and refugia for the bonytail chub exist today in several places: Dexter National Fish Hatchery, New Mexico; Arizona Game and Fish Page Springs Hatchery; Ouray National Wildlife Refuge, Ouray, Utah;
Buenos Aires National Wildlife Refuge Buenos Aires National Wildlife Refuge (Buenos Aires NWR) provides of habitat for threatened and endangered plants and animals. This refuge, in Pima County, Arizona, was established in 1985. Natural history The semidesert grassland supports the ...
, Sasabe, Arizona; Niland Native Fish Ponds, California.


References


External links


''Gila elegans'' Species Profile
U.S. Fish & Wildlife Service (Accessed 2007 Mar 04)
USFWS Environmental Conservation Online System page for Bonytail chub

USFWS Upper Colorado Endangered Fish Recovery ProgramUSFWS List of Fish Listed under Endangered Species Act
{{DEFAULTSORT:Bonytail Chub Chubs (fish) Gila (fish) Taxa named by Spencer Fullerton Baird Taxa named by Charles Frédéric Girard Fish described in 1853 Chub Fish of North America ESA endangered species Freshwater fish of North America