The Gila trout (''Oncorhynchus gilae'') is a species of

salmonid Salmonidae (, ) is a family of ray-finned fish, the only extant member of the suborder Salmonoidei, consisting of 11 extant genera and over 200 species collectively known as "salmonids" or "salmonoids". The family includes salmon (both Atlantic a ...

, related to the

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

, native to the Southwest

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. 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, inv ...

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

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 ...

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

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

, with a special provision called a "4d rule" that will allow limited sport fishing – for the first time in nearly half a century. 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 The Gila River (; O'odham ima Keli Akimel or simply Akimel, Quechan: Haa Siʼil, Maricopa language: Xiil) is a tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed 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 ...

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 The Gila National Forest is a United States national forest in New Mexico. Established in 1905, it now covers approximately , making it the sixth largest national forest in the continental United States. The Forest administration also manage ...

, 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. 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. Gila_trout

Biology

Gila trout can be found in small mountain water

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a strea ...

s, and in confined pools. They are opportunistic feeders that feed on aquatic

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s such as trichopterans, ephemeropterans,

chironomid Chironomidae , commonly known as non-biting midges or chironomids , are a family of Nematoceran flies with a global distribution. They are closely related to the families Ceratopogonidae, Simuliidae, and Thaumaleidae. Although many chironomid s ...

s, and

coleopteran Beetles are insects that form the order Coleoptera (), in the superorder Holometabola. 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 ...

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

. 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 ...

, 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 in 1967 its range had reduced from several hundred miles of stream to just 20 in the Gila Wilderness and Aldo Leopold Wilderness. 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.Springer, Craig (27 September 2006) "Gila trout down-listed to threatened status," ''Fishing World''
/ref> Conservationists hope to eventually delist the species and allow

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

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
{{Authority control Oncorhynchus Cold water fish Fish of the Western United States Freshwater fish of the United States Fauna of the Southwestern United States Natural history of Arizona Gila River White Mountains (Arizona) Fish described in 1950 Endangered fauna of the United States ESA threatened species