In some published literature, this species is treated as a subpopulation of the Bourget Whitefish (Coregonus lavaretus) or a member of the "Coregonus lavaretus species complex", and referred to by the English vernacular names "Common Whitefish" or "European Whitefish" (see below).

At the regional scale, the systematics of European ciscoes and whitefishes (Coregonus spp.) has been the subject of considerable debate since the turn of the 21^st century, with little indication of a definitive outcome.

It is widely accepted that non-anadromous members of this group have repeatedly undergone adaptive radiations in boreal, subarctic and perialpine lakes (Douglas et al. 1999, Østbye et al. 2005, Kahilainen and Østbye 2006, Harrod et al. 2010, Hudson et al. 2011).

Subpopulations inhabiting these systems largely diversified in the wake of the most recent glacial period 10,000-15,000 years ago. They are typified by parallel patterns of divergence in traits associated with foraging (i.e., gill raker counts, benthic vs. pelagic feeding ecology), physiology (i.e., growth rate, habitat depth partitioning) and reproductive ecology (i.e., reproductive timing and spawning habitat).

Up to six different sympatric forms sometimes referred to as “morphs”, "ecomorphs" or "ecotypes" have been recorded in perialpine lakes, and these radiations might be even more diverse in some large systems of northeastern Europe (Præbel et al. 2013, Doenz et al. 2018, Bitz‐Thorsen et al. 2020, Öhlund et al. 2020).

However, there exist significant differences in opinion regarding the taxonomic status of these forms.

In Northern Europe, including the United Kingdom, all except a handful of Irish subpopulations are usually regarded as belonging to two widely-distributed species; Coregonus albula (ciscoes) and C. lavaretus (whitefishes), with the latter also frequently referred to as the "Coregonus lavaretus species complex” (Etheridge et al. 2012, Wanke et al. 2017, Häkli et al. 2018, Crotti et al. 2020). Within this comparatively uniform taxonomic concept, the catch-all English vernacular name “Vendace” is typically used for C. albula while "Common Whitefish" or "European Whitefish" are applied to C. lavaretus.

Conversely, researchers and fisheries authorities based in Central Europe have tended to treat the different forms as distinct taxa, leading to the recognition of more than 60 species across the European region (Kottelat and Freyhof 2007, Selz et al. 2020, De-Kayne et al. 2022, Selz and Seehausen 2023). Under this diverse taxonomic concept, the name “Vendace” is restricted to its original usage for the United Kingdom endemic Coregonus vandesius and the native range of C. lavaretus is limited to its type locality of Lake Bourget in France.

In the absence of a region-wide consensus, the Red List continues to follow the taxonomy provided by Fricke et al. (2024).

Global and European regional assessment: Endangered (EN)
EU 27 regional assessment: Not Recorded

The Neuchâtel Whitefish is endemic to Europe, where it is restricted as native to Lake Neuchâtel, Switzerland. It has been introduced in Italy. The species has a restricted range (extent of occurrence (EOO) c. 250 km², area of occupancy (AOO) c. 220 km²), which meets the threshold for the Endangered category under Criterion B1 (EOO < 5,000 km2) and Criterion B2 (AOO <500 km²). It occurs in one location where the quality of habitat is estimated to be undergoing continuing decline and there is an inferred continuing decline in the number of mature individuals.

Therefore, this species is assessed as Endangered under Criterion B (B1ab(iii,v)+2ab(iii,v)).

This species is natively endemic to Lake Neuchâtel (fr. Lac de Neuchâtel; de. Neuenburgersee) in the upper Rhine River system, Switzerland. It may have formerly occurred in nearby Lake Morat (fr. Lac de Morat; de. Murtensee), where all native whitefish species had been extirpated by the early 20^th century.

The earlier assessment of this species listed introduced occurrence in mainland Italy; this is believed to be an erroneous record.

This species' population size is unknown, but it is understood to exceed the minimum threshold for Red List criteria (< 10,000 mature individuals). The current population trend has not been explicitly quantified.

Overall abundance is inferred to be declining based on recent fisheries data, which demonstrate a significant reduction in commercial landings since 2016 (see 'Use and Trade').

Lake Neuchâtel is a monomictic, perialpine, naturally oligotrophic lake formed after the last glacial period. It has a maximum depth of 152 metres, and is connected to adjacent Lake Morat (fr. Lac de Morat; de. Murtensee) and Lake Biel (fr. Lac de Bienne; de. Bielersee) via separate canalised river channels.

Three whitefish species which differ in traits related to feeding and reproductive ecology along depth gradients were originally native to the lake, among which a putatively undescribed taxon referred to as Coregonus cf. restrictus, C. sp. "grande Bondelle", C. sp "Gibbion", C. sp. "petite Palée" or C. sp. "petite Féra" in some published literature is understood to have become extinct during the 1970s (see 'Threats').

The Neuchâtel Whitefish primarily inhabits the benthopelagic zone at depths of 10-100+ metres. It feeds on both zoobenthos and zooplankton. Male individuals become sexually mature at age 2-3+ and females at age 4+. The annual reproductive period extends throughout January, when spawning takes place at depths of 90-130 metres.

This species is plausibly threatened by declining genetic diversity driven by pronounced changes in the trophic status of Lake Neuchâtel during the 20^th century.

A rising human population in the lake's catchment after 1900 drove the development of industry and agriculture, which led to increasing pollution from domestic wastewater and runoff. The lake subsequently entered a phase of eutrophication, which peaked in the 1970s and led to periodic stratification and anoxia in the hypolimnion. These events are likely to have driven recruitment failure and extinction of the sympatric profundal whitefish subpopulation (see 'Habitat and Ecology') by significantly reducing the extent of habitat and the abundance of zoobenthos which comprised the main component of its diet.

A secondary outcome of such environmental changes is the potential for overlap and increased gene flow between different whitefish species that were formerly segregated along depth gradients. This raises the possibility of speciation reversal and extinction events due to hybridisation and introgression, and such processes may have occurred to some extent in Lake Neuchâtel.

Unregulated stocking with non-native whitefishes from other central Alpine lakes, Eastern Europe and North America occurred for a period from the end of the 19^th century, and the potential of introgressive hybridisation with native taxa cannot be ruled out.

The invasive Quagga Mussel (Dreissena bugensis) was first recorded in Lake Neuchâtel during 2017. Once established, this filter-feeding mollusc can drive driving significant food web alterations, including energy sources and pathways for pelagic fishes, due to its propensity to alter zooplankton abundance, community structure and composition.

Warming of the lake due to climate change constitutes a plausible ongoing and future threat.

This species is harvested commercially, although both annual landings and the number of professional fishers have decreased considerably since the late 1980s. A total of 11 professional licenses were issued in 2020. These outcomes have been partially attributed to the lake's improved trophic status (see 'Conservation'), which is likely to have driven a natural reduction in productivity.

However, the driver(s) of a more recent decline in annual landings, from c. 150-200 tonnes in 2013-2014 to < 50 tonnes in 2019-2020, are in need of clarification (see 'Threats').

This species is included (as Coregonus spp.) in Appendix III of the Bern Convention. Lake Neuchâtel is surrounded by a number of protected areas, some of which are listed as Ramsar Wetlands of International Importance.

Investment in wastewater treatment facilities and other policy-led measures since the 1980s has driven an improvement in water quality, and the lake has returned to its natural oligotrophic state.

An annual species-specific closed fishing season extends from December 14 until February 1 at the earliest, and there is a minimum catch size of 25 centimetres when the fishery is open. The translocation of non-native whitefishes has been prohibited throughout Switzerland since 1991.

This species is not well-studied, and research focused on its demographics (population size and trend) and response to the identified ongoing threats is strongly recommended.