Oncorhynchus mykiss aguabonita - Jordan, 1892
California Golden Trout
Synonym(s): Oncorhynchus aguabonita aguabonita ;Oncorhynchus aguabonita (Jordan, 1892)
Taxonomic Status: Accepted
Related ITIS Name(s): Oncorhynchus mykiss aguabonita (Jordan, 1892) (TSN 553419)
Unique Identifier: ELEMENT_GLOBAL.2.101620
Element Code: AFCHA0209A
Informal Taxonomy: Animals, Vertebrates - Fishes - Bony Fishes - Salmon and Trouts
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Actinopterygii Salmoniformes Salmonidae Oncorhynchus
Genus Size: C - Small genus (6-20 species)
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Concept Reference
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Concept Reference: Lee, D. S., C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, North Carolina. i-x + 854 pp.
Concept Reference Code: B80LEE01NAUS
Name Used in Concept Reference: Oncorhynchus mykiss aguabonita
Taxonomic 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.
Conservation Status
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NatureServe Status

Global Status: G5T1
Global Status Last Reviewed: 03Jun2013
Global Status Last Changed: 21May2001
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: 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.
Nation: United States
National Status: N1 (21May2001)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Arizona (SNA), California (S1), Colorado (SNA), Idaho (SNA), Montana (SNA), Nevada (SNA), New Mexico (SNA), Oregon (SNA), Utah (SNA), Washington (SNA), Wyoming (SNA)

Other Statuses

American Fisheries Society Status: Threatened (01Aug2008)

NatureServe Global Conservation Status Factors

Range Extent: 1000-5000 square km (about 400-2000 square miles)
Range Extent Comments: 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).

Area of Occupancy: 3-25 4-km2 grid cells
Area of Occupancy Comments: Area occupied by nonhybridized golden trout is very small (Stephens et al. 2004, Cordes et al. 2006).

Number of Occurrences: 1 - 5
Number of Occurrences 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.

Number of Occurrences with Good Viability/Integrity: None (zero)

Overall Threat Impact: High
Overall Threat Impact 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).

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Trend over the past 10 years or three generations is uncertain, but the abundance of nonhybridized golden trout probably has been slowly declining.

Long-term Trend: Decline of >90%
Long-term Trend Comments: Nonhybridized California golden trout are restricted to less than 1 percent of their native range (Cordes et al. 2001, 2003).

Other NatureServe Conservation Status Information

Distribution
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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).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.

Map unavailable!:
Distribution data for U.S. states and Canadian provinces is known to be incomplete or has not been reviewed for this taxon.
Endemism: endemic to a single state or province

U.S. & Canada State/Province Distribution
United States AZexotic, CA, COexotic, IDexotic, MTexotic, NMexotic, NVexotic, ORexotic, UTexotic, WAexotic, WYexotic

Range Map
No map available.


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Tulare (06107)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
18 Upper Kern (18030001)+, South Fork Kern (18030002)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A trout with black-spotted dorsal and caudal fins, golden sides, red belly, red-orange lateral band; less than 71 cm long.
Reproduction Comments: 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.
Ecology Comments: Density ranges up to 4644 individuals per kilometer of stream (see Matthews 1996).
Habitat Type: Freshwater
Non-Migrant: N
Locally Migrant: N
Long Distance Migrant: N
Mobility and Migration Comments: During a week-long study in July, radio-tagged individuals moved little, stayed within 5 meters of previously recorded location (Matthews 1996).
Riverine Habitat(s): CREEK, High gradient, MEDIUM RIVER, Moderate gradient, Pool, Riffle
Lacustrine Habitat(s): Deep water, Shallow water
Special Habitat Factors: Benthic
Habitat 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).

Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food 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).
Economic Attributes Not yet assessed
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Management Summary
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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."

Management Requirements: CDFG and Inyo National Forest have made repeated efforts to eradicate brown trout and restock golden trout (USFWS 2002).
Monitoring Requirements: USFS (Inyo National Forest) is developing a monitoring strategy to determine watershed recovery from impacts of cattle grazing, with a comparison of currently grazed areas with areas in which grazing has been removed (USFWS 2002). A small amount of active restoration will be done by USFS (USFWS 2002).

See Knapp and Vrendenburg (1996) for information on redd-sampling devices.

Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 03Jun2013
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 03Jun2013
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Behnke, R. J. 1992. Native trout of western North America. American Fisheries Society Monograph 6. xx + 275 pp.

  • Berg, W. J. 1987. Evolutionary genetics of rainbow trout, PARASALMO GAIRDNERII (Richardson). Ph.D. Diss., Univ. California, Davis.

  • Christianson, D. P. 1978. A fishery management plan for the Little Kern golden trout. California Dept. Fish & Game,Inland Fisheries Endangered Species Program Special Publ. 78-1. January 1978.

  • Cordes, J. F., M. A. Blumberg, G. A. E. Gall, and B. May. 2001. Genetic status of California golden trout populations in the headwaters of Golden Trout Creek. Genomic Variation Laboratory, University of California, Davis. Report to the Threatened Trout Committee, Calif. Dept. of Fish and Game. 34 pp.

  • Cordes, J. F., M. R. Stephens, M. A. Blumberg, and B. P. May. 2006. Identifying introgressive hybridization in native populations of California golden trout based on molecular markers. Transactions of the American Fisheries Society 135:110-128.

  • Cordes, J. F., M. R. Stephens, and B. P. May. 2003. Genetic status of California golden trout in the South Fork Kern River and transplanted Populations. Genomic variation Laboratory, University of California, Davis. Report to the Threatened Trout Committee, Calif. Dept. of Fish and Game. 67 pp.

  • Eschmeyer, William N. (editor). 1998. Catalog of fishes. Volumes 1-3. California Academy of Sciences, San Francisco, California. 958 pp. Updates available online at: http://www.calacademy.org/research/ichthyology/catalog/

  • Everhart, W. H. and W. R. Seaman. 1971. Fishes of Colorado. Colorado Game, Fish and Parks.

  • Jelks, H. L., S. J. Walsh, N. M. Burkhead, S. Contreras-Balderas, E. Díaz-Pardo, D. A. Hendrickson, J. Lyons, N. E. Mandrak, F. McCormick, J. S. Nelson, S. P. Platania, B. A. Porter, C. B. Renaud, J. Jacobo Schmitter-Soto, E. B. Taylor, and M.L. Warren, Jr. 2008. Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries 33(8):372-407.

  • Knapp, R. A., V. T. Vredenburg, and K. R. Matthews. 1998. Effects of stream channel morphology on golden trout spawning habitat and recruitment. Ecological Applications 8:1104-1117.

  • Knapp, R. A., and V. T. Vrendenburg. 1996. A field comparison of the substrate composition of California golden trout redds sampled with two devices. North American Journal of Fisheries Management 16:674-681.

  • La Rivers, I. 1994. Fishes and fisheries of Nevada. University of Nevada Press, Reno. 782 pp.

  • Lee, D. S., C. R. Gilbert, C. H. Hocutt, R. E. Jenkins, D. E. McAllister, and J. R. Stauffer, Jr. 1980. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, North Carolina. i-x + 854 pp.

  • Matthews, K. R. 1996. Habitat selection and movement patterns of California golden trout in degraded and recovering stream sections in the Golden Trout Wilderness, California. North American Journal of Fisheries Management 16:579-590.

  • Moyle, P. B. 1976a. Inland fishes of California. University of California Press, Berkeley, California. 405 pp.

  • Moyle, P. B., J. E. Williams, and E. D. Wikramanayake. 1989. Fish species of special concern of California. Final report submitted to California Dept. of Fish and Game, Inland Fisheries Division, Rancho Cordova. 222 pp.

  • Page, L. M., H. Espinosa-Pérez, L. T. Findley, C. R. Gilbert, R. N. Lea, N. E. Mandrak, R. L. Mayden, and J. S. Nelson. 2013. Common and scientific names of fishes from the United States, Canada, and Mexico. Seventh edition. American Fisheries Society, Special Publication 34, Bethesda, Maryland.

  • Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes: North America north of Mexico. Houghton Mifflin Company, Boston, Massachusetts. 432 pp.

  • Page, L. M., and B. M. Burr. 2011. Peterson field guide to freshwater fishes of North America north of Mexico. Second edition. Houghton Mifflin Harcourt, Boston. xix + 663 pp.

  • Popov, B. H., and J. B. Low. 1953. Game, fur animal and fish introductions into Utah. Utah State Dept. Fish and Game, Misc. Publ. No. 4. i-iii + 1-85 pp.

  • Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A. Lachner, R.N. Lea, and W.B. Scott. 1991. Common and scientific names of fishes from the United States and Canada. American Fisheries Society, Special Publication 20. 183 pp.

  • Sigler, W. F., and J. W. Sigler. 1987. Fishes of the Great Basin: a natural history. University of Nevada Press, Reno, Nevada. xvi + 425 pp.

  • Sigler, W. F., and R. R. Miller. 1963. Fishes of Utah. Utah Department of Fish and Game, Salt Lake City, Utah. 203 pp.

  • Smith, G. R., and R. F. Stearley. 1989. The classification and scientific names of rainbow and cutthroat trouts. Fisheries (Bethesda) 14(1):4-10.

  • Stearley, R. F. 1992. Historical ecology of Salmoninae, with special reference to Oncorhynchus. Pages 622-658 in R.L. Mayden, editor. Systematics, historical ecology, and North American freshwater fishes. Stanford University Press, Stanford, California. xxvi + 969 pp.

  • Stephens, S. J., C. McGuire, and L. Sims. 2004. Conservation assessment and strategy for the California golden trout (Oncorhynchus mykiss aguabonita) Tulare County, California. California Department of Fish and Game, San Joaquin Valley and Southern Sierra Region; USDA Forest Service, Pacific Southwest Region, Inyo National Forest, Sequoia National Forest; U. S. Fish and Wildlife Service, Sacramento Office.

  • Stoltz, J., and J. Schnell (eds.). 1991. Trout: The Wildlife Series. Stackpole Books, Harrisburg, Pennsylvania. 384 pp.

  • U.S. Fish and Wildlife Service (USFWS). 20 September 2002. 90-day finding on a petition to list the California golden trout as endangered. Federal Register 67:59241-59243.

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