This species is listed as Least Concern in view of the large extent of occurrence (EOO), large number of subpopulations, large population size, and lack of major threats. Trend over the past 10 years or three generations is uncertain but likely relatively stable, or the species may be declining but not fast enough to qualify for any of the threatened categories under Criterion A (reduction in population size). However, it should be noted that treatment at species-level masks many significant declines that are in progress and well documented.

Anadromous forms of this species occur in Pacific Coast drainages from Eel River, California, north to Prince William Sound, Alaska, and generally not more than 160 km inland. Non-migrating fish also occur through this range. Allopatric inland forms occur in the Rocky Mountains, in Hudson Bay basin, Mississippi River basin, Great Basin (including Lahontan, Bonneville, and Alvord basins), and Pacific basin from southern Alberta south through California to the Rio Grande drainage, New Mexico, and east to Colorado and Montana (Lee et al. 1980, Page and Burr 1991). The greatest abundance of pure interior Cutthroat Trout occurs in Yellowstone Lake and the Yellowstone River drainage above the falls in Yellowstone National Park (Behnke 1992).

It is widely stocked in and out of the original range. It is established in Laurentian Lakes, Quebec. However, rarely has become naturalized much beyond the original distribution (Behnke 1992). Occurrence in high elevation headwater lakes is due primarily to introductions (formerly excluded by falls) (Behnke 1992).

Tokranov and Sheiko (2006) consider this species native to Kamchatka, Russia where specimens with morphological similarities to North American populations have been recorded in the Tigil' River and Krutogorova River. However, further study and voucher specimens are still needed to validate the occurrence of this species in Kamchatka (Parin et al. 2014).

This species is represented by a large number of subpopulations. It is locally common (Page and Burr 1991). The total adult population size is unknown but relatively large.

Sea-run Cutthroat Trout underwent a major decline in the 1970s and 1980s (Nehlsen et al. 1991). Of the 13 non-coastal subspecies tentatively recognised by Behnke (1992), two apparently are extinct as pure populations and ten have suffered catastrophic declines; one of the two regarded as relatively stable (Whitehorse Cutthroat, undescribed) exists in a small range that is severely degraded (Behnke 1992). See Gresswell (1988) for information on the status of various subspecies in several areas. Of 612 anadromous stocks in British Columbia and Yukon, Slaney et al. (1996) categorized 15 as extirpated, 16 as high risk, 5 as moderate risk, 30 as special concern, 54 as unthreatened, and 492 as unknown status.

There is a decline in more southern subspecies, including O. c. virginalis, O. c. henshawi and O. c. utah. These declines are due to the combination of restricted habitat size coupled with non-native trouts and other non-native species. Declines seem to be synergised by climate-driven disturbances. For example, in Great Basin, Cheat Grass (non-native grass) is changing wildfire frequency and resulting in population losses for O.c. henshawi.   

This species occurs in estuaries or marine waters near the coast, small rivers, gravelly streams, and isolated mountain lakes. Spawning usually occurs in gravel stream riffles where the female digs a nest (redd) in the gravel.

Declines have occurred primarily because of habitat degradation/destruction and the effects of introduced trout species. The greatest threat is introgressive hybridisation among subspecies and with Rainbow Trout/Steelhead (Allendorf and Leary 1988). This is a major concern in inland populations, but hybridisation may also occur in coastal populations (Baker et al. 2002).

Subspecies macdonaldi (Yellowfin Cutthroat), formerly in Twin Lakes, Lake County, Colorado, is extinct apparently due to introgressive hybridisation with Rainbow Trout and competition from deep-water Lake Trout (Miller et al. 1989).

An unnamed subspecies from Alvord Basin, south-eastern Oregon (Trout Creek) and north-western Nevada (Virgin Creek), is extinct as a pure form, apparently due to hybridisation and introgression with introduced Rainbow Trout; no genetically pure populations are known (Miller et al. 1989).

Behnke (1992) described instances in which Cutthroat Trout were quickly replaced by Brook Trout, both with and without associated habitat disturbance.

Sea-run Cutthroat Trout underwent a major decline in the 1970s and 1980s, evidently due to habitat damage and overfishing; for populations above Bonneville Dam, dam passage takes a toll; in many areas, native stocks have been eroded by introductions of hatchery stock (Nehlsen et al. 1991).

There is no use or trade information for this species.

Currently, on a range-wide basis, this species is of relatively low conservation concern and does not require significant additional protection or major management, monitoring, or research action. However, certain local subspecies (ssp. stomias, ssp. henshawi and ssp. seleniris) are of conservation concern and are listed as Threatened pursuant to US Endangered Species Act (US Fish and Wildlife Service 2020).

Where non-native trout pose a threat to native Cutthroat Trout populations and restoration, isolated headwater reaches managed for cutthroat trout should be as large and diverse as possible, and improvements may be needed to ensure that habitat requirements are met (Novinger and Rahel 2003).

Though most high-elevation populations have been exposed to hybridisation and are not pure native trout, Behnke (1992) noted that they do maintain the appearance of native trout and recommended that they be recognised and managed as such.

See Nehlsen et al. (1991) for general protection and management recommendations for anadromous salmonids.

This species occurs within the Yellowstone National Park, America, has been shown to be in decline there, and key threats include invasive species, habitat degradation, and climate change (Gresswell 2011).

While focus on species-level status assessments are an important first step, the IUCN Species Survival Commission (SSC) Salmon Specialist Group (SSG) emphasizes the need to characterize status of Pacific Salmon at a more granular, population-level scale (identified as “subpopulations” in the IUCN Red List Guidelines) to provide meaningful guidance to stem the loss of biodiversity across the natural range of the species. There are many examples of declines in wild Pacific Salmon in both North America and Asia, particularly in the southern portion of their range given the degree of degradation and fragmentation of habitat there and the more immediate risk of climate change impacts. At the same time, there are large-scale ocean drivers that appear to be affecting species broadly across the North Pacific, regardless of their freshwater origin. Two excellent examples exist of assessment approaches and policies in the US (Waples 1991) and Canada (DFO 2005, COSEWIC 2018) that establish an effective framework for Pacific Salmon conservation. These efforts involve identifying population units based on a variety of criteria including examination of traits that are important in the evolutionary process and future adaptation. In these examples, assessments are conducted at a more granular, population-level, resulting in listings for individual population units, with identification of needed conservation actions specific to each unit. An example of assessing range-wide status of the species and at the individual subpopulation level in the IUCN Red List now exists for Oncorhynchus nerka (Rand 2011). While the amount of effort required to rigorously assess the species is substantial, we encourage efforts like this applied to the other species in the genus.