The Gila trout (''Oncorhynchus gilae'') is a species of salmonid, related to the

rainbow A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured circular arc. Rainbows c ...

, native to the Southwest

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

. Prior to 2006 the Gila trout was federally 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 and in ...

. In July 2006, after much work by the Game and Fish departments in

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ke ...

and Arizona, the US Forest Service and the US Fish and Wildlife Service, the Gila trout was down-listed to

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

, with a special provision called a "4d rule" that will allow limited sport fishing – for the first time in nearly half a century. This possibility is distinct: there may be no one alive today that has legally angled a pure Gila trout from its native waters. By the time the Gila trout was closed to fishing in the 1950s, its numbers and range were so depleted and so reduced this copper-colored trout simply wasn't very accessible to anglers. As of 2011 there is fishing in both states for this fish.

Range

The Gila trout is native to tributaries of the Gila River in

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

and

. The Gila trout is found historically in the Verde and Agua Fria drainages in Arizona. A note in the archives of Aldo Leopold, dated 1923, contains anecdotal evidence of a native trout in Tonto Creek, AZ. Gila trout have persisted in five streams within the Gila National Forest, New Mexico, including: Iron, McKenna, and Spruce creeks in the Gila Wilderness Area, along with Main and South Diamond creeks in the Aldo Leopold Wilderness Area.

Description

Gila trout have a yellow body, with black spots. The average total length is about ; with maximum total length approximately . Gila trout are closely related to

Apache trout The Apache trout, ''Oncorhynchus apache'', is a species of freshwater fish in the salmon family (biology), family (family Salmonidae) of order (biology), order Salmoniformes. It is one of the Pacific trouts. Description The Apache trout measur ...

. However, Apache trout can have a spot behind and in front of the pupil (eye) and big noticeable spots on the body whereas Gila trout are characterized by numerous small dark spots on the upper half of the body.

Biology

Gila trout can be found in small mountain water streams, and in confined pools. They are opportunistic feeders that feed on aquatic

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

s such as trichopterans, ephemeropterans,

chironomid The Chironomidae (informally known as chironomids, nonbiting midges, or lake flies) comprise a family of nematoceran flies with a global distribution. They are closely related to the Ceratopogonidae, Simuliidae, and Thaumaleidae. Many specie ...

s, and

coleopteran Beetles are insects that form the order Coleoptera (), in the superorder Endopterygota. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 400,000 described ...

s, as well as small fishes.

Reproduction

Depending on the water temperature, spawning season occurs in late spring and summer. The number of

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the a ...

s produced from females held in hatcheries averaged about 150. The maximum fecundity observed was 686 eggs.

Conservation

The Gila trout has been threatened by competition and hybridization with introduced game fish such as the rainbow trout. However, the primary cause of reduced Gila trout populations is habitat loss caused by loss of water flow and shade-giving trees, caused in turn by fires, human destruction of riparian vegetation, livestock

overgrazing Overgrazing occurs when plants are exposed to intensive grazing for extended periods of time, or without sufficient recovery periods. It can be caused by either livestock in poorly managed agricultural applications, game reserves, or nature res ...

, agricultural irrigation and water diversion, and channelization of streams in the Gila trout's native range. By the time the Gila trout was listed by the

U.S. Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with othe ...

in 1967 its range had reduced from several hundred miles of stream to just 20 in the

Gila Wilderness Gila Wilderness was designated the world's first wilderness area on June 3, 1924. Along with Aldo Leopold Wilderness and Blue Range Wilderness, the 558,014 acre (225,820 ha) (872 sq. mi.) wilderness is part of New Mexico's Gila National Forest. ...

and

Aldo Leopold Wilderness Aldo Leopold Wilderness, along with Gila Wilderness and Blue Range Wilderness, is part of New Mexico's Gila National Forest. It became part of the National Wilderness Preservation System in 1980 by an act of the United States Congress and has a ...

. After listing USFWS began an aggressive program of stream restoration, removing the introduced trout, restoring and repairing riparian vegetation (to maintain cooler water temperatures), and restocking restored streams with young Gila trout. The Mora National Fish Hatchery and Technology Center in northern New Mexico keeps brood stocks of the Gila trout and supplies the fish for restocking. The species is now more secure than it was in the 1970s, having been moved to 10 new streams, though populations and habitat are still far below those originally established. Conservationists hope to eventually delist the species and allow

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

ing, thus forming alliances with fishermen in order to help preserve the species. Major wildfires and drought will always play a major role in the status of any trout species.

Notes

References

* Listed as Endangered (EN B2ad+3c v2.3) * *

External links

YouTube video Catching A Gila Trout
{{Taxonbar, from=Q596296 Oncorhynchus Cold water fish Trout, Gila Trout, Gila Trout, Gila Natural history of Arizona Gila River White Mountains (Arizona) Fish described in 1950 Trout, Gila ESA threatened species