Golden trout
Conservation status
Critically Imperiled (NatureServe)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Salmoniformes
Family:	Salmonidae
Genus:	Oncorhynchus
Species:	O. aguabonita
Binomial name
Oncorhynchus aguabonita (Jordan, 1892)[2]
Kern River trout range map
Synonyms
Oncorhynchus mykiss aguabonita

TheCalifornia golden trout (Oncorhynchus aguabonita) is aspecies oftrout native toCalifornia. The golden trout is normally found in theGolden Trout Creek (tributary to theKern River), Volcano Creek (tributary to Golden Trout Creek), and theSouth Fork Kern River. The Golden trout has been the official freshwaterstate fish of California since 1947.^[3][4]

The California golden trout is closely related to tworainbow trout subspecies. TheLittle Kern golden trout (O. m. whitei), found in theLittle Kern River basin, and theKern River rainbow trout (O. m. gilberti), found in theKern River system. Together, these three trout form what is sometimes referred to as the "golden trout complex".^[5]

Originally the golden trout was described as a subspecies of the salmon species, with a nameSalmo mykiss agua-bonita,^[6] and it is still often considered a subspecies (now calledOncorhynchus mykiss aguabonita) along with several other rainbow trout subspecies commonly known asredband trout.

FishBase and theCatalog of Fishes however now (2014) listO. aguabonita as an independent species rather than as subspecies ofO. mykiss.^[6][7] Likewise, whileITIS listsO. m. whitei andO. m. gilberti as subspecies ofO. mykiss,^[2]O. aguabonita instead is listed as a full species.^[8][9]

The golden trout has golden flanks with red, horizontal bands along the lateral lines on each side and about 10 dark, vertical, oval marks (called "parr marks") on each side. Dorsal, lateral and anal fins have white leading edges. In their native habitat, adults range from 6 to 12 inches (15 to 30 cm) long. Fish over 12 inches (30 cm) are considered large. Golden trout that have been transplanted to lakes have been recorded up to 11 pounds (5.0 kg).

The golden trout should be distinguished from the similarly named goldenrainbow trout, also known as the palomino trout. The golden rainbow is a color variant of the rainbow trout.^[10]

The golden trout is commonly found at elevations from 6,890 feet (2,100 m) to 10,000 feet (3,000 m) abovesea level, and is native toCalifornia's southernSierra Nevada mountains. Outside of its native range in California, Golden trout are more often found in cirques and creeks in wilderness areas around 10,500–12,000 feet (3,200–3,700 m) elevation, often in higher passes that are not passable without crampons, ice axes, and ropes until after the Fourth of July.^[11] Their preferred water temperature is 58 to 62 °F (14 to 17 °C) but they can tolerate temperatures in degraded streams on the Kern Plateau as high as 70 °F (21 °C) so long as those waters cool during the night.^[11] The only other species of fish indigenous to the native range of California golden trout is theSacramento sucker (Catostomus occidentalis occidentalis).^[12]

The Wyoming Game & Fish Department state record golden trout measured 28 in (71 cm) and weighed 11 lb 4 oz (5.1 kg), caught in Cooks Lake, Wyoming in 1948.^[13] TheIGFA "All-Tackle Length Record" forO. aguabonita measured 21 in (53 cm) caught in Golden Lake, Wyoming in 2012.^[14]

O. m. aguabonita is native to the southern Sierra Nevada, including the upper reach and tributaries of the South Fork of the Kern River, and Golden Trout Creek and its tributaries.^[1] It has been introduced in hundreds of lakes and streams outside the native range, though most of these populations did not last or hybridized with cutthroat trout and other subspecies of rainbow trout.^[1]

In 1892, the California golden trout was originally described byDavid Starr Jordan, the first President ofStanford University, asSalmo mykiss agua-bonita. The fish was named after the Agua Bonita Waterfall where the first specimens were collected, at the mouth of Volcano Creek, at the creek's confluence with the Kern River.^[15] A century later they were listed asOncorhynchus mykiss aguabonita inBehnke'sNative trout of western North America.^[16]

In 1904, Stewart Edward White communicated to his friend PresidentTheodore Roosevelt, that overfishing could lead to extinction of the golden trout. In White's novelThe Mountains, he wrote about the threatened golden trout on California's Kern Plateau. Roosevelt shared White's concern and, through U.S. Fish Commissioner George M. Bowers, dispatched biologistBarton Warren Evermann of the U.S. Bureau of Fisheries to study the situation. In 1906 Evermann publishedThe Golden Trout of the Southern High Sierras.^[17] Based on morphology, Evermann accurately described four forms of this native fish:Salmo roosevelti from Golden Trout (Volcano) Creek,Salmo aguabonita from nearby South Fork of the Kern River,Salmo whitei (named in recognition of Stewart Edward White) from the Little Kern River, andSalmo gilberti, the Kern River rainbow.^[12]

Genetic studies have since clarified three groups of trout native to the Kern River: California golden trout (O. m. aguabonita) native to the South Fork Kern River and Golden Trout Creek (tributary to the Kern River mainstem but the historic course of the South Fork Kern River and now only separated from it by a lava flow and ridge of sediment), Little Kern River golden trout (O. m. whitei), and Kern River rainbow trout (O. m. gilberti).^[18]

Years ofoverexploitation, mismanagement and competition withexotic species have brought golden trout to the brink of being designated as "threatened".^{[citation needed]} Introducedbrook trout (Salvelinus fontinalis) outcompete them for food, introducedbrown trout (Salmo trutta) prey on them and introduced rainbow trout (O. mykiss) hybridize with them, damaging the native gene pool throughintrogression. Populations have been in steady decline for decades.

In 1978, theGolden Trout Wilderness was established withinInyo National Forest andSequoia National Forest, protecting the upper watersheds of the Kern River and South Fork Kern River. It also resulted in the closure of the Tunnel Air Camp airstrip and air charters operations for sport fishermen in the region.^[19]

In September 2004, theCalifornia Department of Fish and Game signed an agreement with federal agencies to work on restoring back-country habitat, heavily damaged byovergrazing from cattle and sheep, as part of a comprehensive conservation strategy.^[11]

TheUS Endangered Species Act (USESA) designated the subspeciesO. m. whitei as LT, or Listed Threatened, since 1978, under the nameOncorhynchus aguabonita whitei.^[20]

NatureServe has designated the followingNatureServe Conservation Status for the three subspecies:

• Oncorhynchus mykiss aguabonita—Golden trout (G5T1):Critically Imperiled, last reviewed in 2013.^[1] The primary threat is hybridization and introgression with stocked rainbow trout.^[1] Other threats include competition with non-native brown trout and rainbow trout, predation by brown trout, habitat degradation from cattle grazing, and possibly expanding beaver populations in the native range.^[1] Genetic studies showed hybridization with stocked rainbow trout in almost all known wild populations analyzed to as of 2003.^[1] Non-hybridized populations are restricted to less than 1% of their native range, and confinement to these areas for long periods create a significant risk of inbreeding depression, and loss of heterozygosity and genetic variance.^[1]
• Oncorhynchus mykiss gilberti—Kern River rainbow trout (G5T1Q):Critically Imperiled, with questionable taxonomy that may reduce conservation priority, last reviewed in 2005.^[21] Few if any genetically pure populations still exist. Primary threats include continued introgression with introduced rainbow trout, habitat loss from grazing, logging and road building, unpredictable events such as floods, drought, and fire (and subsequent landslides), and reduced habitat availability due to introduced beaver.^[21]
• Oncorhynchus mykiss whitei—Little Kern golden trout (G5T2Q):Imperiled, with questionable taxonomy that may reduce conservation priority, last reviewed in 2005.^[20] Hybridization with introduced rainbow trout is considered a threat, and "there is a constant threat from introductions of other salmonids by disgruntled anglers."^[20] The subspecies still occurs in the Little Kern River, above the falls on the lower river, though some populations show signs of introgression with coastal rainbow trout.^[20]

The American Fisheries Society has designated all three subspecies asThreatened since August 2008.^[1][20][21]

The Golden Trout is an endangered species in California. In 1991, the fish was added to the U.S. Fish and Wildlife Service’s list.^[22] This is in efforts to protect the species legally and create measures to ensure their survival. The government is allowed to make recovery plans, restrict commercial trade, and purchase habitats.^[23]

The areas used for cattle grazing have been decreased and fencing is enforced in certain areas to ensure cows do not enter the stream.^[24] Though scientists are still studying the ecosystems, many improvement projects are still developing.

The population of Golden Trouts in their original habitat has strongly decreased in recent times. In 1965 there were about 40,000 golden trout. In most recent times there are only 400-2,600 recorded to be within a distance of the Volcano Creek.^[25] It is challenging to keep an accurate record of the population because many of them are no longer within their habitats.  

The decrease in population size is a reflection of the decrease in habitat size. Originally the total habitat of the Golden Trout was around 450 square miles (1,200 km²).^[22] In recent times, the golden trout is only secure in 20 square miles (52 km²), a dramatic decrease to only about 4% of its original habitat. Moreover, the streams that they inhabit are also decreasing. A survey of Volcanic Creek showed that the stream decreased from 2.1 kilometres (1.3 mi) in 2013, to 1.4 kilometres (0.87 mi) in 2014, to 1 kilometre (0.62 mi) in 2015.^[26] The continuous decline in the stream shows the low quality of habitat the Golden trout experiences in recent times.

For sportfishing, the golden trout underwent many twentieth century translocations into multiple Western states and established populations survive inCalifornia,Idaho,Montana,Utah,Washington,Colorado, andWyoming. Populations in the high-elevation lakes in theRuby Mountains,Nevada, have died out.^[27] The current status in other states where the California golden trout were planted (Arizona,New Mexico andOregon) lacks documentation.

However, a former New Mexico population is relatively well known and storied as, when then-ColonelChuck Yeager introduced one of his commanding officers,GeneralIrving "Twig" Branch, to theSierra Nevada populations of golden trout, Branch ordered Yeager andBud Anderson to introduce the species to the mountain streams ofNew Mexico.^[28] These New Mexico populations have since also died out.^[27] In his second memoir,Press On, Yeager detailed his annual fishing trips to catch golden trout which he extols as one of the best game fish and best eating fish to be found.

A self-sustaining introduced population also exists in the Rocky Mountains ofAlberta,Canada; the province's golden trout population is managed by translocating fish between lakes to balance populations, but no new fish from other populations are introduced.^[29]

Golden trout were also introduced to Kilnsley Park,Yorkshire Dales inEngland.^[30]

• Garibaldi (the state saltwater fish of California)

• Finkel, David (Summer 2005)."The New Gold Rush: Celebrating and Protecting the California Golden Trout in the Sierra Nevada"(PDF).The American Fly Fisher.31 (3):10–21. Archived fromthe original(PDF) on 2014-11-29. Retrieved2014-11-16.

• NatureServe critically imperiled species
• Oncorhynchus
• Endemic fauna of California
• Fauna of the Sierra Nevada (United States)
• Fish of the Western United States
• Freshwater fish of the United States
• Fish described in 1892
• Critically endangered fish
• Critically endangered fauna of California
• Symbols of California
• Subspecies
• Freshwater fish of North America
• Taxa named by David Starr Jordan

• Articles with short description
• Short description matches Wikidata
• Articles with 'species' microformats
• All articles with unsourced statements
• Articles with unsourced statements from December 2013