endemic to a single state or province
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Native to and still occurs in the Little Kern River, Tulare County, California; occurs above the falls on the lower river (Moyle 2002). Some populations show signs of introgression with coastal rainbow trout, despite efforts to eliminate non-native trouts and hybrids (Moyle 2002).
Length: 31 cm
Habitat Type: Freshwater
Comments: Small, clear, cool, swift-flowing streams (Matthews and Moseley 1990). Spawns in gravel riffles (Matthews and Moseley 1990).
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.
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).
National NatureServe Conservation Status
Rounded National Status Rank: N2 - Imperiled
NatureServe Conservation Status
Rounded Global Status Rank: T2 - Imperiled
Reasons: Small range in the Little Kern River, Tulare County, California; protection and restoration have improved status, but vulnerable to detrimental introductions of other salmonids by disgruntled anglers.
Global Short Term Trend: Decline of 10-30%
Comments: Due to the persistence of hybrids, and efforts to eliminate them, the trend has not yet stabilized.
Global Long Term Trend: Decline of 50 to >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).
Degree of Threat: High
Comments: Hybridization with introduced rainbow trout is still a threat (Moyle 2002). There is a constant threat from introductions of other salmonids by disgruntled anglers.
Formerly this species was greatly impacted by the presence of non-native trouts and by logging, overgrazing, and other activities that degraded habitat.
This fish can withstand light use of streams by humans and livestock.
Global Protection: Few to several (1-12) occurrences appropriately protected and managed
Comments: Protected in the Golden Trout Wilderness Area and in streams designated as Critical Habitat. Main channel and tributary streams of Little Kern River have been designated as Critical Habitat.
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).