The golden trout is found in high altitude fresh bodies of water in the western area of the United States. Specifically, this species can be found in Wyoming, Idaho, Washington, and most abundantly in California, where it was first discovered.
Biogeographic Regions: nearctic (Native )
Global Range: (1000-5000 square km (about 400-2000 square miles)) This subspecies is native to the southern Sierra Nevada: upper reach and tributaries of the South Fork of the Kern River, and Golden Trout Creek and its tributaries, an area encompassing approximately 1,536 square kilometers, at elevations generally above 2,100 meters (Moyle 2002, USFWS 2002, Stephens et al. 2004). It has been introduced within the native basins and in hundreds of lakes and streams outside the native range; most of the populations outside the native range did not persist or have hybridized with cutthroat trout and other subspecies of rainbow trout, but there are some populations that may not have been affected by hybridization (Stephens et al. 2004).
endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Golden trout are small sized members of the trout family with an overall golden color and orangish-red stripes along the side. The rear portion of the body right before the tail is often speckled with dark spots, and so is the dorsal fin. Small scales are also a distinguishing characteristic.
Range mass: 0.02 to 5 kg.
Other Physical Features: bilateral symmetry
Golden trout occupy only high altitude fresh water lakes and rivers, usually in scenic mountain areas that are highly inaccessible and can only be reached by horseback riding or backpacking. These altitudes can range anywhere from 9000-12000 feet. The water in which the fish dwell is usually of very low temperatures and is of great beauty, hence, the name, aguabonita. The waters contain little weed growth.
Aquatic Biomes: lakes and ponds; rivers and streams
Habitat Type: Freshwater
Comments: This subspecies thrives in cold, clear mountain streams and lakes (Moyle et al. 1989, Moyle 2002, Stephens et al. 2004). Golden trout evolved in the absence of- other salmonids, and generally they are unable to coexist with them. Population density is greatest in low gradient meadow reaches with deep pools, undercut banks, aquatic vegetation, and streamside sedge cover (Matthews 1996).
Spawning occurs in gravel riffles in streams, rarely in lakes (Moyle et al. 1989). At about 45 mm TL, fry move into lakes from spawning streams (pertains only to lake populations) (Moyle et al. 1989).
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
During a week-long study in July, radio-tagged individuals moved little, stayed within 5 meters of previously recorded location (Matthews 1996).
The diet of the golden trout consists mainly of surface water-dwelling insects, principally small ones such as caddisflies and midges. Small crustaceans such as tiny fresh water shrimp as well as some terrestrial insects contribute to the diet as well. However, small insects, either in larvae or fully developed form, floating on the surface compose most of the natural food of this species. To feed, the trout opens its gills and hinged mouth and inhales its prey whole in the water. The water is then pushed back out of the gills, acting much like a filter, leaving only the food in its mouth. The primary feeding season is from May through September, because there is a scarcity of insects found during the colder season.
Comments: Diet includes a wide variety of invertebrates (primarily aquatic insects and their larvae in streams; caddisfly larvae, chironomid midge larvae, and planktonic crustaceans in lakes (Moyle 1976).
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 5
Comments: There is only one documented remaining nonhybridized population in the native range, in a tributary of Golden Trout Creek, and this is a small population with low viability and high vulnerability to threats (Stephens et al. 2004, Cordes et al. 2006).
This subspecies has been introduced in many high mountain lakes and streams outside the native range, but surviving populations generally have hybridized with other trout.
Density ranges up to 4644 individuals per kilometer of stream (see Matthews 1996).
Life History and Behavior
Perception Channels: tactile ; chemical
The female golden trout's egg development starts early in their short growing season. The egg is almost completely ripe when lowering temperatures arrest development at the onset of winter. The fish are then ready to spawn the following spring. Provoked by the melting snow and thawing streams, the spawning routine, which starts anytime between March through July, begins its process, depending on weather conditions and elevation. Reproduction is sexual with external fertilization. The female lays her eggs in specific areas, and the males then come and fertilize them. The development of the egg, hatching, and early growth stages are virtually the same as in the other spring spawners.
Spawning occurs late May-August, usually late June and July, whenever water temperatures reach 7 to 10 C. Depending on size a female may lay 300-2300 eggs. Eggs hatch in about 20 days at 14 C (Moyle 1976). Fry emerge from gravel 2-3 weeks after hatching (Moyle et al. 1989). These trout are relatively long-lived and slow growing; sexually mature in 3-4 years, live 6-7 years in alpine lakes.
The California Department of Fish and Games Committee on Threatened Trout has been active in working to protect and enhance the survival of the species. Attempts to widely stock the western states have been made but many populations do not last long. The population of golden trout in the South Fork Kern River was reduced by the presence of brown trout. Golden trout are now more abundant, however, than they have been in the past.
National NatureServe Conservation Status
Rounded National Status Rank: NNA - Not Applicable
Rounded National Status Rank: N1 - Critically Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: T1 - Critically Imperiled
Reasons: Very small native range in the Kern River drainage in California, but widely introduced; threatened primarily by hybridization, competition, and other negative interactions with non-native trouts.
Global Short Term Trend: Relatively stable to decline of 30%
Comments: Trend over the past 10 years or three generations is uncertain, but the abundance of nonhybridized golden trout probably has been slowly declining.
Global Long Term Trend: Decline of >90%
Comments: Nonhybridized California golden trout are restricted to less than 1 percent of their native range (Cordes et al. 2001, 2003).
Degree of Threat: High
Comments: Major threats include: hybridization and introgression with stocked rainbow trout (this is the primary threat), competition with non-native brown trout and rainbow trout, predation by brown trout, habitat degradation from cattle grazing in meadows (e.g., bare and collapsed banks) and off-highway vehicle use, and inadequacy of existing regulatory mechanisms ((Matthews 1996; petition, cited by USFWS 2002; Stephens et al. 2004). Expanding beaver populations in the native range may pose a threat (Stephens et al. 2004).
Genetic studies indicate hybridization with hatchery-raised rainbow trout in most all of the known wild populations of California golden trout analyzed to date in Golden Trout Creek, the upper South Fork Kern River , and in transplanted populations outside of the California golden trout's native range (Cordes et al. 2001, 2003). "Hybridization has spread throughout the vast majority of California golden trout populations within the affected stream reaches, and absent specific conservationactions, it poses a serious threat to the continued existence of the subspecies" (Stephens et al. 2004). "Hybridized fish occupy a large geographic extent of habitats within their native range, rendering such habitats unavailable for the natural restoration and repatriation of nonhybridized California golden trout populations" (Stephens et al. 2004).
If confined to the few existing localized sites for long periods, the non-hybridized populations of California golden trout are at significant risk of inbreeding depression and the loss of heterozygosity and genetic variance, and they are at risk of extinction from catastrophic events due to drought, fire, over-fishing, and unauthorized fish introductions (Stephens et al. 2004).
Management Requirements: CDFG and Inyo National Forest have made repeated efforts to eradicate brown trout and restock golden trout (USFWS 2002).
Global Protection: Few (1-3) occurrences appropriately protected and managed
Comments: Native range is within Inyo National Forest (INF). The current occupied habitat on the INF is mostly contained within the Golden Trout and South Sierra wilderness areas. Sequoia National Forest manages lands on the lower South Fork Kern river.
Relevance to Humans and Ecosystems
The main benefit is that goldens attract fishers and are prime food fish, either pan sauted or smoked. It is of little interest to tourists unless the tourists are fishing fanatics eager to catch a rare golden while enjoying the beautiful area in which the trout occur.
Stewardship Overview: Stephens et al. (2005) listed the following needed conservation actions (in order of priority): "1) elimination of new sources of non-native rainbow trout genetic contamination; 2) population surveys and genetic evaluations; 3) refuge establishment, including locations both within and outside the upper Kern River Basin; 4) management actions to safely isolate nonhybridized and low-level hybridized California golden trout populations in streams, using natural or constructed fish passage barriers in combination with removal of fish with relatively higher levels of hybridization; 5) restoration of riparian and meadow habitats, including the restoration of habitats degraded from permitted livestock grazing and other activities; and 6) adaptively manage and monitor actions using the latest information and technology."
Stephens et al. (2004) stated that "the remaining known non-hybridized populations are so geographically restricted and small in population size that they are unlikely to represent a gene pool that is large enough to assure the long-term genetic viability of California golden trout. In fact these populations are not representative of all of the California golden trout alleles found in the hybridized populations (Cordes et al. 2001). As such, it is important to retain and manage some of the remaining hybridized populations for future gene-pool security and management, even if today we have no way to isolate or otherwise purify those genetic stocks."
The California golden trout, or simply the golden trout (Oncorhynchus mykiss aguabonita), is a subspecies of the rainbow trout native to California. The golden trout is native to Golden Trout Creek (tributary to the Kern River), Volcano Creek (tributary to Golden Trout Creek), and the South Fork Kern River.
The California golden trout is closely related to two other rainbow trout subspecies. The Little Kern golden trout (O. m. whitei), found in the Little Kern River basin, and the Kern River rainbow trout (O. m. gilberti), found in the Kern River system. Together, these three trout form what is sometimes referred to as the "golden trout complex".
Originally the golden trout was described as a subspecies of the rainbow trout, with a name Salmo mykiss agua-bonita, and it is still often considered a subspecies (now called Oncorhynchus mykiss aguabonita) along with several other rainbow trout subspecies commonly known as redband trout.
FishBase and the Catalog of Fishes however now (2014) list O. aguabonita as an independent species rather than as subspecies of O. mykiss. Likewise, while ITIS lists O. m. whitei and O. m. gilberti as subspecies of O. mykiss, O. aguabonita instead is listed as a full species.
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 is commonly found at elevations from 6,890 feet (2,100 m) to 10,000 feet (3,000 m) above sea level, and is native only to California's southern Sierra Nevada mountains. 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. The only other species of fish indigenous to the native range of California golden trout is the Sacramento sucker (Catostomus occidentalis occidentalis).
The Wyoming Game & Fish Department state record golden trout measured 28 in (71 cm) and weighed 11.25 lb (5.10 kg), caught in Cook Lake, Wyoming in 1948. The IGFA "All-Tackle Length Record" for O. m. aguabonita measured 21 in (53 cm) caught in Golden Lake, Wyoming in 2012.
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. 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. Distribution data that may be incomplete or inaccurate includes the Canadian province of Alberta, and the US states of Arizona, California, Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, Utah, Washington, and Wyoming.
In 1892 the California golden trout was originally described by David Starr Jordan, the first President of Stanford University, as Salmo 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. A century later they were listed as Oncorhynchus mykiss aguabonita in Behnke's Native trout of western North America.
In 1904 Stewart Edward White communicated to his friend President Theodore Roosevelt, that overfishing could lead to extinction of the golden trout. In White's novel The 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 biologist Barton Warren Evermann of the U.S. Bureau of Fisheries to study the situation. In 1906 Evermann published The Golden Trout of the Southern High Sierras. 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, and Salmo gilberti, the Kern River rainbow.
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).
Years of overexploitation, mismanagement and competition with exotic species have brought golden trout to the brink of being designated as "threatened". Introduced brook trout (Salvelinus fontinalis) outcompete them for food, introduced brown trout (Salmo trutta) prey on them and introduced rainbow trout (O. mykiss) hybridize with them, damaging the native gene pool through introgression. Populations have been in steady decline for decades.
In September 2004, the California Department of Fish and Game signed an agreement with federal agencies to work on restoring back-country habitat, heavily damaged by overgrazing from cattle and sheep, as part of a comprehensive conservation strategy.
- Oncorhynchus mykiss aguabonita: G5T1, Critically Imperiled, last reviewed in 2013. The primary threat is hybridization and introgression with stocked rainbow trout. 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. Genetic studies showed hybridization with stocked rainbow trout in almost all known wild populations analyzed to as of 2003. 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.
- Oncorhynchus mykiss gilberti: G5T1Q, Critically Imperiled, with questionable taxonomy that may reduce conservation priority, last reviewed in 2005. 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.
- Oncorhynchus mykiss whitei: G5T2Q, Imperiled, with questionable taxonomy that may reduce conservation priority, last reviewed in 2005. Hybridization with introduced rainbow trout is considered a threat, and "there is a constant threat from introductions of other salmonids by disgruntled anglers." 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.
Translocations outside of endemic range
For sportfishing, the California golden trout underwent many twentieth century translocations into multiple Western states and established populations survive in California, Idaho, Montana, Utah, Washington and Wyoming. Populations in the high-elevation lakes in the Ruby Mountains, Nevada, have died out.
Chuck Yeager and the New Mexico population
When Colonel Chuck Yeager introduced one of his commanding officers, General Irving "Twig" Branch, to the Sierra Nevada populations of golden trout, Branch ordered Yeager and Bud Anderson to introduce the species to the mountain streams of New Mexico. However, the New Mexico populations have also died out.
In his second autobiography, Press On, Yeager details 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.
- "Oncorhynchus mykiss aguabonita". Integrated Taxonomic Information System. Retrieved 27 December 2013.
- Inland Fishes of California, By Peter B. Moyle. Page 20.
- W. Eschmeyer (2014) aguabonita, Salmo mykiss Catalog of Fishes. California Academy of Sciences. (accessed 3 Nov 2014)
- Froese, Rainer and Pauly, Daniel, eds. (2014). "Oncorhynchus aguabonita" in FishBase. April 2014 version.
- "Oncorhynchus mykiss". Integrated Taxonomic Information System. Retrieved 27 January 2013.
- "Oncorhynchus aguabonita". Integrated Taxonomic Information System. Retrieved 27 January 2013.
- Journal of Applied Ichthyology, Volume 16 Issue 3 Page 117-120, June 2000<http://www.blackwell-synergy.com/doi/abs/10.1046/j.1439-0426.2000.00147.x>
- Stanley J. Stephens, Christy McGuire, Lisa Sims (2004-09-17). Conservation Assessment and Strategy for the California Golden Trout (Oncorhynchus mykiss aguabonita) Tulare County, California (Report). California Department of Fish and Game. http://www.tucalifornia.org/cgtic/GTCAssessmnt&Strategy9-04.pdf. Retrieved 2012-10-14.
- Edwin Philip Pister. "California Golden Trout: Perspectives on Restoration and Management". Fisheries 35 (11): 550–553. doi:10.1577/1548-8446-35.11.550.
- "Wyoming's Record Fish". Wyoming Game and Fish Department. 27 December 2013.
- IGFA World Records
- Hammerson, G (2013). "Comprehensive Report Species – Oncorhynchus mykiss aguabonita". NatureServe Explorer. NatureServe Inc. Retrieved 27 December 2013.
- David Starr Jordan (1892-07-24). "A description of the golden trout of Kern River, California, Salmo mykiss agua-bonita.". Proceedings United States National Museum xv: 481–483. doi:10.5479/si.00963801.15-916.481. Retrieved 2012-10-16.
- Robert J. Behnke (1992). Native trout of western North America. Monograph No. 6. American Fisheries Society. p. 275. ISBN 9780913235799.
- Barton Warren Evermann, Oliver Peebles Jenkins, Chancey Juday (1906). The golden trout of the southern high Sierras. Government Printing Office. p. 51. Retrieved 2012-10-15.
- Molly R. Stephens (2007). Systematics, genetics and conservation of golden trout. Ph.D. dissertation. (Thesis). University of California Davis. Retrieved 2012-10-14.
- Hopkins, T; Moyle, P; Hammerson, G (2005). "Comprehensive Report Species – Oncorhynchus mykiss whitei". NatureServe Explorer. NatureServe Inc. Retrieved 27 December 2013.
- Hopkins, T; Moyle, P; Hammerson, G (2005). "Comprehensive Report Species – Oncorhynchus mykiss gilberti". NatureServe Explorer. NatureServe Inc. Retrieved 27 December 2013.
- Pam Fuller and Matt Neilson (2012-03-29). "Oncorhynchus aguabonita (Jordan, 1892)". USGS Nonindigenous aquatic species (NAS) database. Retrieved 2012-10-14.
- Yeager, Chuck and Janos, Leo. Yeager: An Autobiography. Pages 348-351 (paperback). New York: Bantam Books, 1986. ISBN 0-553-25674-2.
- Finkle, David (Summer 2005). "The New Gold Rush: Celebrating and Protecting the California Golden Trout in the Sierra Nevada". The American Fly Fisher (The American Museum of Fly Fishing) 31 (3): 10–21. Retrieved 2014-11-16.
Names and Taxonomy
Comments: Taxonomic relationships have been the subject of much confusion and controversy. Generally this trout has been regarded as specifically distinct from O. mykiss (rainbow trout), but Berg (1987) concluded that the two recognized subspecies of O. aguabonita are more closely related to the Kern River rainbow trout (O. mykiss gilberti) than they are to each other; hence they were regarded as subspecies of mykiss (followed by Moyle et al. 1989). The 1991 AFS checklist (Robins et al. 1991) and Page and Burr (1991) continued to recognize aguabonita as a species distinct from O. mykiss, but they did not comment upon the findings of Berg (1987).
Behnke (1992) grouped the Kern and Little Kern golden trout as one subspecies (gilberti) of O. mykiss. He stated that they could be recognized as separate subspecies (gilberti and whitei, respectively) provided they are kept together in the same species (O. mykiss). Behnke indicated that whitei may be indistinguishable from gilberti. Behnke (2002) treated these forms as three subspecies: Golden Trout Creek golden trout or California golden trout (O. mykiss aguabonita), Kern River rainbow trout (O. mykiss gilberti), and Little Kern River golden trout (O. mykiss whitei).
Nominal taxon roosevelti from Golden Trout Creek is a color variant of subspecies aguabonita.
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