This taxon is currently regarded as valid for global Red List purposes, but was treated as a subpopulation of the Arctic charr, Salvelinus alpinus (Linnaeus 1758), for the most recent national assessment (Nunn et al. 2023).

The taxonomic status of Salvelinus subpopulations inhabiting the British Isles has not been definitively resolved since a series of endemic species were described between the mid-19^th and early 20^th centuries (Adams & Maitland 2007).

In the United Kingdom and Ireland, all of these taxa are treated as junior synonyms of the Arctic Charr, the name of which has been routinely applied to a widespread complex of polymorphic charr populations occurring throughout the Holarctic region (Jonsson & Jonsson 2001). However, there remains considerable uncertainty regarding the systematics of the genus across the majority of this range (Reist et al. 2013; Taylor 2016; Whiteley et al. 2019).

Members of this "Arctic Charr complex" exhibit bewildering subpopulation-scale ecological and morphological variability. When such divergence occurs within a single lake system, the different sympatric forms are often referred to as “morphs”, “morphotypes”, "ecomorphs" or "ecotypes" (Snorrason et al. 1994; Adams et al. 1998; Knudsen et al. 2006; Klemetsen 2010; Muir et al. 2016).

Some of these subpopulations and sympatric forms have over time been described as nominal species, including at least 15 from North America, around 30 from Europe and 12 from Siberia and the Far East. However, these taxa encompass only a small fraction of charr distribution and diversity, and there exist significant differences in opinion regarding which of them should be considered valid (Savvaitova 1995; Adams & Maitland 2007; Kottelat & Freyhof 2007; Klemetsen 2010; Whiteley et al. 2019).

With the above in mind, there is an emerging consensus that the striking genetic and phenotypic diversity exhibited by members of this genus cannot be adequately represented by a single accepted taxonomic system (Whiteley et al. 2019).

The Red List currently follows the nomenclature provided by Fricke et al. (2024), albeit a species-oriented conservation management approach is unlikely to prove appropriate for members of this genus (Barthelemy et al. 2023; also see 'Conservation').

Global and European regional assessment: Vulnerable (VU)
EU 27 regional assessment: Not Recorded

The Killin Charr has an extremely restricted range (extent of occurrence (EOO) c. 65 km², area of occupancy (AOO) c. 4 km²), which meets the thresholds for the Critically Endangered category under Criterion B1 (EOO < 100 km²) and Criterion B2 (AOO < 10 km²). It is restricted to one location, but there is no indication of continuing decline or extreme fluctuations, hence it does not qualify for a threatened category under Criterion B.

There is no evidence of any population size reduction that would approach the threshold for Vulnerable under Criterion A (≥ 30% over the past ten years or three generations). The population size is unknown, precluding the use of Criterion C or Criterion D1, and there exists no quantitative analysis of extinction probability which would permit application of Criterion E.

Therefore, this species is assessed as Vulnerable under Criterion D2, based on its presence at one location which is threatened by habitat modification and climate change that could drive it to Critically Endangered or Extinct in a very short time period.

This species is endemic to Loch Killin in the Ness River system, Highland council area, northern Scotland, United Kingdom.

The small size of this lake precludes its accurate depiction on the range map accompanying this assessment.

Putatively conspecific subpopulations inhabit Loch Doine in the upper Teith River system, Loch Builg in the upper Spey River system and perhaps some other Scottish lakes. However, their identities have never been explicitly confirmed and they are not considered for the purposes of this assessment.

This species' current population size and trend have not been quantified, but there is no evidence of continuing decline.

It remains extant according to anglers’ reports and unpublished sampling records (C. Adams pers. comm.), but no other information is available.

Lough Killin is located in a relatively remote, steep-sided valley and has not been extensively-studied. It was formed after the last glacial period, has a maximum depth of c. 20.5 metres and drains to the much larger Loch Ness via the outflowing Felchin River.

The Killin Charr is understood to occupy deeper habitats in the pelagic zone, where it feeds on aquatic invertebrates.

Little is known of its life history, but it is believed to move inshore to spawn in shallow littoral or sublittoral zones during the annual reproductive period, which extends from September to October. Mature individuals are likely to develop an intense epigamic colour pattern at this time.

Construction of an extensive wind farm in the upper portion of the Loch Killin catchment was completed in 2018. It is unclear whether construction of this facility has negatively impacted the lake, but any increase in sediment load could plausibly reduce the extent of suitable spawning habitat available to the Killin Charr.

Installation of a proposed dam on the outflow of Loch Killin to the Felchin River represents a potential threat should it interfere with the lake's water level, since it may result in dewatering of spawning and nursery sites.

Increased sedimentation and fluctuating water levels could also lead to changes in the population structure of benthic invertebrates, and thus affect food availability.

Rising water temperatures due to climate change represents a plausible future threat.

This species was apparently harvested for food at the local scale during the 19^th century, but is no longer used or traded. It is occasionally landed by fly anglers targeting sympatric Brown Trout (Salmo trutta).

The Killin Charr is included (as Salvelinus alpinus) as a priority species of conservation concern in the U.K. Post-2010 Biodiversity Framework.

This species is not currently recognised by the relevant authorities in Scotland or the United Kingdom, where it is treated as a subpopulation of the Arctic Charr (Salvelinus alpinus). The taxonomy of Eurasian charrs is in need of review (see 'Taxonomic Notes'), and it has been widely recommended that their conservation management must be considered independent of their systematic classification. Each subpopulation should therefore be assessed individually, taking into account its evolutionary and genetic significance coupled with the ongoing population trend and threats to result in a priority ranking permitting the effective allocation of conservation resources through the development of site-specific, catchment-scale management plans. Sympatric morphological forms should also be managed separately, depending on their respective habitat preferences, diets and life histories. The abundance trends of many subpopulations remain unknown, and their individual assessments should ideally form the basis of future research efforts in order to ensure appropriate prioritisation. In practice, such efforts should ideally be coordinated at local, national or regional scales.