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: Extinct (EX)
EU 27 regional assessment: Extinct (EX)

The Strumose Whitefish was endemic to Lake Constance, which is bordered by Switzerland, Germany and Austria. The species has not been observed in the wild since the 1970s and no ex situ populations exist, therefore the species is assessed as Extinct.

This species was endemic to Lake Constance (fr. Lac de Constance; de. Bodensee) in the upper Rhine River system, which is bordered by Switzerland, Germany and Austria.

This species has probably been extinct since the 1970s, since when no individuals have been reported in commercial landings or scientific surveys.

Lake Constance is a monomictic, perialpine, naturally oligotrophic lake formed after the last glacial period. It has a total surface area of 536 km², divided between the large (472 km²), deep (>250 metres) Upper Lake (de. Obersee) and the smaller (63 km²), shallower Lower Lake (de. Untersee).

The Strumose Whitefish was a relatively small species that mostly inhabited the profundal zone at depths exceeding 100 metres. The annual reproductive period took place during summer, although some reports suggest that it extended from July to November, and spawning took place at depths of 10-60 metres. It fed primarily on zoobenthos, particularly molluscs.

Four whitefish species which differ in traits related to feeding and reproductive ecology along depth gradients were native to the lake prior to extinction of the Strumose Whitefish. The other three remain extant, and comprise the pelagic-spawning Blaufelchen (Coregonus wartmanni), inshore-spawning Gangfisch (C. macrophthalmus) and demersal Sandfelchen (C. arenicolus).

Two additional whitefish populations have been recognised in the Lake Constance system. One mostly inhabits the Lower Lake and is sometimes referred to as Coregonus sp. "Weissfelchen", while the other is restricted to the Upper Lake but migrates into the Alpine Rhine River for spawning and is therefore known as C. sp. "Alpenrheinfelchen". These might represent still-undescribed species, although genetic analyses indicate that C. sp. "Alpenrheinfelchen" is potentially conspecific with the Sandfelchen.

A rising human population in the Lake Constance catchment during the 20^th century 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 1979 and led to periodic stratification and hypolimnetic anoxia. The Strumose Whitefish is understood to have become extinct during this period since it was a stenotypic resident of the profundal zone and unable to survive in the deoxygenated hypolimnion. In addition, the natural reproduction of the remaining whitefish stock was inhibited, since their eggs could no longer develop in the oxygen-depleted substrata.

Upper Lake Constance has since returned to its former oligotrophic state following the successful implementation of management measures, while the Lower Lake is currently mesotrophic.

This species was harvested commercially until the 1960s.

Taxonomic resolution of this group of species is required.