Global Range: (<100 square km (less than about 40 square miles)) This subspecies is native to and still occurs in the Little Kern River drainage, Tulare County, California; it occurs above the falls on the lower river (Moyle 2002).
Historically, the Little Kern golden trout occupied approximately 160 kilometers of the Little Kern River and its tributaries (Moyle 2002). By 1973, the range was greatly reduced to five headwater streams (upper Soda Springs Creek, Deadman Creek, lower wet meadows creek, Willow Creek, and Fish Creek), and an introduced population in Coyote Creek, or approximately 10 percent of the historical range (Christenson 1984, Moyle 2002). Between 1974 and 1995, a series of chemical treatments were conducted in an effort to remove introgressed Little Kern golden trout populations throughout the basin. Little Kern golden trout were then reintroduced from a few local donor populations, yet introgressed populations continue to persist in the Little Kern River drainage (Stephens 2007). The current range of the Little Kern golden trout is therefore difficult to ascertain because restocked populations continue to exhibit rainbow trout alleles at low, moderate and even high levels (USFWS 2011). The most recent genetic evidence suggests that the least genetically compromised Little Kern golden trout populations (exhibiting between 0-2 percent introgression levels) exist in Upper North Fork Clicks Creek, Upper Clicks Creek, Trout Meadow Creek, Little Kern River above Broder's cabin, and Little Kern River above Wet Meadow Creek (Stephens 2007, 2010), With the exception of Coyote Creek, a stream immediately adjacent to the Little Kern River drainage, no known populations of Little Kern golden trout occur outside of the Little Kern River watershed (C. McGuire, personal communication, 2011, cited by USFWS 2011).
endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Length: 31 cm
Habitat Type: Freshwater
Comments: Small, clear, cool, swift-flowing streams (Matthews and Moseley 1990). Little Kern golden trout require cool, oxygenated water with significant clean gravel for reproduction (USFWS 2011).
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.
Comments: Food primarily aquatic insects.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: 1 - 20
Comments: Current distribution of pure Little Kern golden trout is limited to a few small populations (USFWS 2011).
2500 - 10,000 individuals
Comments: Due to both inconsistent count methodology and incorrect assumptions concerning the level of hybridization, the current abundance of the Little Kern golden trout cannot be determined (USFWS 2011). However, based on occupied stream kilometers and typical densities (see USFWS 2011), the overall population likely is at least several thousand.
Life History and Behavior
Spawns usually in late June; males are sexually mature in about two years, females in three years (Matthews and Moseley 1990).
NatureServe Conservation Status
Rounded Global Status Rank: T2 - Imperiled
Reasons: Small range in the Little Kern River drainage, Tulare County, California; protection and restoration have improved status, but still affected by and vulnerable to detrimental introductions of other salmonids.
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
Global Short Term Trend: Relatively stable (=10% change)
Comments: Trend over the past 10 years or three generations is uncertain, but distribution and abundance probably have been relatively stable.
Global Long Term Trend: Decline of 50-90%
Comments: Prior to federal listing, unhybridized populations of this subspecies were reduced to about 10 percent of the original 160 km of stream (Moyle 2002). The presence of hybrid trouts in the native range of this subspecies is still a problem (Moyle 2002, USFWS 2011).
Degree of Threat: Medium
Comments: The principal cause of decline was hybridization with introduced coastal rainbow trout; other causes of decline included competition with non-native salmonids such as brook trout, and habitat degradation from logging and grazing practices (Christenson 1978, Moyle 2002). Mining and logging currently are not regarded as significant threats, but livestock grazing may be affecting some populations (USFWS 2011).
The most recent genetic studies, using both mitochondrial and nuclear DNA, suggest that while some populations show low levels of introgression, others continue to show moderate levels (Stephens 2007, Stephens and May 2010). With respect to the moderate and high levels of hybridization, Upper Mountaineer Creek, Alpine Creek, Jacobson Creek, South Mountaineer Creek, Shotgun Creek, Peck's Canyon Creek, Lion Creek, Tamarack Creek, Little Kern River at Burnt Corral, Lower Maggie Lake, and Silver Lake all provide serious concerns for the genetic integrity of the Little Kern golden trout (USFWS 2011).
Hybridization with introduced rainbow trout is still a threat (Moyle 2002). There is a constant threat from introductions of other salmonids by disgruntled anglers.
Due to reduced genetic variation, Little Kern golden trout populations may be particularly vulnerable to stochastic events and/or changing habitat conditions associated with climate change (USFWS 2011). Predicted outcomes of climate change imply that negative impacts on trout will occur through increases in stream temperatures, decreases in stream flow, and broader changes to the stream hydrograph (USFWS 2011).
This fish can withstand light use of streams by humans. Recreational use associated with trails and route proliferation does not appear to be a threat at this time (USFWS 2011).
Global Protection: Few to several (1-12) occurrences appropriately protected and managed
Comments: Most occurrences are in the Golden Trout Wilderness of Sequoia National Forest. Smaller areas are in either Sequoia National Park or the Sequoia National Forest. The main channel and tributary streams of the Little Kern River have been designated as Critical Habitat.
Relevance to Humans and Ecosystems
Stewardship Overview: Restoration efforts have focused primarily on removing introgressed populations and non-native salmonids and constructing fish barriers to prevent upstream movement of non-native fishes.(USFWS 2011). Introduced populations of brook and rainbow trout have been greatly reduced via chemical treatments in the Little Kern drainage, and it is unlikely that brown trout occupy the drainage due to effective fish barriers on the Little Kern River. However, chemical treatments used to eradicate these fishes ended in 1995 and more recent data on the distribution of these introduced fishes in the Little Kern River and its tributaries are not currently available (USFWS 2011).
Revised Fishery Management Plan for the Little Kern golden trout requires: 1) periodic habitat surveys of instream, riparian, and greater landscape processes, 2) restoration of damaged habitat in portions of Fish Creek, Lion creek, Grey Meadow Creek, Coffin Meadow, Round Meadow, Jug Spring, Clicks Creek and other areas as needed and where feasible, 3) resource monitoring programs at five representative sites through periodic sampling of abiotic and biotic factors, and 4) acquisition of land area within the critical habitat boundary when possible (USFWS 2011).
USFWS (2011) made the following recommendations for conservation actions over the next five years:
1. Update the current Fishery Management Plan with a formal genetics management plan for the Little Kern River drainage with specific actions that increase genetic diversity and restore pure populations of Little Kern golden trout throughout their entire historical range. Regularly monitor Little Kern golden trout population trends throughout the drainage as guided by the most recent genetic information. If Little Kern golden trout hatchery programs are reinitiated, ensure facilities are entirely separated from rainbow trout production programs.
2. Initiate a systematic habitat monitoring program in the Little Kern drainage that regularly (every five years) assesses stream conditions throughout the drainage, including both abiotic (temperature, water quality, bank stabilization, sediment distribution, riparian vegetation recruitment, etc.) and biotic (macroinvertebrate surveys and Little Kern golden trout population surveys) factors. More sensitive stream sites, such as those located in the Little Kern and Jordan grazing allotments should be monitored more regularly (every two years).
3. Install and regularly maintain riparian fencing on streams in the Little Kern and Jordan grazing allotments, especially those in low gradient meadow reaches such as Lion, Grey, and Loggy meadows.
4. Regularly evaluate the structural integrity of stream barriers and their ability to inhibit the dispersal of non-native salmonids throughout the Little Kern River drainage (especially during high water years) and make improvements where necessary. Assess the benefits of barriers in terms of preventing non-native salmonid dispersal and compare with the potential genetic costs of these barriers in terms of reducing gene flow between naturally occurring populations of Little Kern golden trout.
Little Kern golden trout
The Little Kern golden trout (Oncorhynchus mykiss whitei) is a brightly colored subspecies of rainbow trout native to the main stem and tributaries of the Little Kern River in Tulare County, California. Together with the California golden trout (the state fish of California) and the Kern River rainbow trout, the Little Kern golden trout forms what is sometimes referred to as the "golden trout complex" of the Kern River basin.
The evolutionary relationships between salmonoids is a matter of ongoing discovery, and there are different opinions about how specific populations should be grouped and named. The same can be said for the Little Kern Golden trout, which has experienced several classification revisions since its first formal description.
The Little Kern golden trout was first described as Salmo Whitei in 1906 by the biologist Barton Warren Evermann in his book ...The Golden Trout of the Southern High Sierras. Everman had been sent to the Kern Plateau by Theodore Roosevelt, after Roosevelt's friend Stewart Edward White had expressed concern that the brightly colored trout of the region were at risk of being fished into extinction. Everman named the fish in honor of White's role in its recognition.
In 1989, morphological and genetic studies by Gerald Smith and Ralph Stearley indicated that trouts of the Pacific basin were genetically closer to Pacific salmon (Onchorhynchus species) than to the Salmos; brown trout (Salmo trutta) or Atlantic salmon (Salmo salar) of the Atlantic basin. Furthermore, in 1992 the Little Kern Golden trout was then classified as a subspecies of rainbow trout (Oncorhynchus mykiss) by Robert J. Behnke. This led to the classification most commonly accepted today; Oncorhynchus mykiss whitei.
The Little Kern golden trout is a brightly colored fish with profuse black spots on the back and tail. The belly and cheeks are typically a bright orange to orange-red. The lower sides of the fish range from a light yellow to bright gold. The back is olive green. The pectoral, pelvic and anal fins are orange with white tips. Unlike many varieties of rainbow trout, but similar to other redband trout and trout in the "Golden Trout Complex", the Little Kern Golden Trout typically retain into adulthood up to ten parr marks along their sides. There is also often an intermediate row of smaller parr marks occurring above and/or below the main row of parr marks.
Morphologically, the Little Kern Golden Trout, sits somewhat in between the California golden trout and the typical coastal rainbow trout (Oncorhynchus mykiss irideus). Compared to the California golden trout, the brilliance of coloration in the Little Kern golden trout is usually a bit more subdued. Little Kern goldens tend to have more black spots along its back, especially anterior to the caudal peduncle, and onto its head in comparison to California golden trouts. Compared to coastal rainbow trout, Little Kern goldens tend to have fewer, larger, and rounder spots. Little Kern golden trout in their native small stream habitat rarely exceed 12 inches in length and any fish exceeding 10 inches would be considered large.
Historic range and habitat
Little Kern golden trout historically occupied roughly 100 miles of the Little Kern River and its tributaries above a natural waterfall barrier preceding its confluence with the main stem Kern River.
As a result of hybridization with hatchery rainbow trout introduced into its watershed, the Little Kern golden trout as a distinct subspecies experienced a widespread contraction in its range. By the 1960s it was limited to only about 8 miles of small headwater streams above three natural barriers. To address the problems of hybridization, planting of non-native trout ceased in the 1950s, and the California Department of Fish and Game (CDFG) began surveys in 1965 to initiate restoration efforts. Allozyme electrophoretic analyses begun in 1976 at UC Davis ultimately identified, what they thought were six pure populations of Little Kern Golden Trout. Restoration efforts began in 1975 with the first rotenone treatments being used to kill off non-native fish in the historic habitat. After chemical treatments there was a period of restocking of treated waters with pure Little Kern golden trout raised at the Kern River Fish Hatchery near Kernville, CA from broodstock collected in the six "pure" populations previously identified. Additional restoration efforts included construction of barriers to the upstream movement of non-native trout, habitat improvement of streams damaged by cattle grazing, public education, and continued monitoring of fish populations, their genetic integrity, and habitat conditions. By 1996, restoration was believed to have been complete.
Later studies showed that one of the six populations used to form the Little Kern River golden trout broodstock, clustered genetically with California golden trout and rainbow trout instead of Little Kern golden trout. This study also showed that one individual fish collected as broodstock from Deadman Creek genetically clustered entirely with hatchery rainbow trout reference populations. This individual was likely inadvertently mixed with pure Little Kern Golden trout at the Kern River Fish Hatchery. The consequence of these two oversights meant that fish hybridized with rainbow trout and California golden trout were reintroduced back into Little Kern habitat.
An additional shortfall of the recovery is that the broodstock populations all came from small headwater streams with small individual populations and low genetic diversity. It is likely that the original removal of hybridized fish from the Little Kern Basin, also removed some native Little Kern golden genetic diversity that now cannot be restored. There is concern that the adaptability of the species has suffered as a result leading to an increased risk of extinction from disease or climate change. Furthermore, these populations are markedly divergent from each other; reflecting long isolation and population structure. Future work is needed to determine the extent to which divergent populations should be admixed when trying to expand the species back into its native range.
- "Species Profile for Little Kern Golden trout (Oncorhynchus aguabonita whitei)". ecos.fws.gov. Retrieved 5 October 2014.
- "Oncorhynchus mykiss whitei". Integrated Taxonomic Information System. Retrieved 27 December 2013.
- "California State Fish - California Golden Trout". statesymbolsusa.org. Retrieved 5 October 2014.
- Inland Fishes of California, By Peter B. Moyle. Page 20.
- Evermann, B.W.; Jenkins, O.P.; Juday, C. (1906). ... The Golden Trout of the Southern High Sierras. U.S. Government Printing Office. Retrieved 5 October 2014.
- Gerald R. Smith, Ralph F. Stearley (1989). "The Classification and Scientific Names of Rainbow and Cutthroat Trouts". Fisheries (American Fisheries Society) 14 (1): 4–10. doi:10.1577/1548-8446(1989)014<0004:tcasno>2.0.co;2.
- Robert J. Behnke (1992). Native trout of western North America. Monograph No. 6. American Fisheries Society. ISBN 9780913235799.
- "ITIS Standard Report Page: Oncorhynchus mykiss whitei". itis.gov. Retrieved 5 October 2014.
- "CGTIC: Little Kern Golden Trout". tucalifornia.org. Retrieved 5 October 2014.
- Behnke, Robert J.; Tomelleri, Joseph R. (illustrator) (2002). "Golden Trout of the Kern River Drainage". Trout and Salmon of North America. New York: The Free Press. p. 107. ISBN 0-7432-2220-2.
- Evans, W.A., R.C. Smith, and M. Bell. 1973. A reconnaissance survey of the fish resources of the Little Kern River drainage, California. U.S. Dept. Agriculture Forest Ser., Region 5, and Ca. Dept. Fish Game Draft (Prelininary Report). 41 p.
- "Molly's Little Kern Golden Trout". animalscience.ucdavis.edu. Retrieved 5 October 2014.
- Gall, G.E., and B. May. 1997. Trout of the Kern River Basin: A genetic analysis of Little Kern River and Golden Trout Creek populations. Report to California Department of Fish and Game, Threatened Trout Committee. September 1997. 55 pp.
- Systematics, Genetics and Conservation of Golden Trout By Molly Rebecca Stephens, 2007
Names and Taxonomy
Comments: 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 O. mykiss (followed by Moyle et al. 1989). The 1991 AFS checklist (Robins et al. 1991) and Page and Burr (1991) continued to recognize aguabonita and mykiss as separate species, 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).
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