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).

The known native range of the Schaal Whitefish comprised lakes Schaal (de. Schaalsee) and Selent (de. Selenter See) in northern Germany. However, the only extant subpopulation inhabits Lake Drewitz, to which it was introduced during the early 1930s, and this subpopulation is included in the present assessment since the intent of the introduction may have been to reduce the extinction risk of the taxon, the occupied site is geographically close to the natural range, viable offspring have been produced, and at least five years have passed since the introduction.

The species has a restricted range (extent of occurrence (EOO) c. 12 km², area of occupancy (AOO) c. 8 km²), which meets the thresholds for the Critically Endangered category under Criterion B1 (EOO < 100 km²) and Criterion B2 (AOO < 100 km²). It is restricted to a single 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 itself is unknown, precluding the use of Criterion C and 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 with the plausible future threats of climate change and the introduction of non-native species which could drive it to Critically Endangered or Extinct in a very short time period.

This species' known native range comprised lakes Schaal (de. Schaalsee) and Selent (de. Selenter See) in the states of Schleswig-Holstein and Mecklenburg-Vorpommern, northern Germany. However, the only extant subpopulation inhabits Lake Drewitz (de. Drewitzer See) in Mecklenburg-Vorpommern, to which it was introduced during the early 1930s (see 'Population'). This subpopulation is included in the present assessment since the intent of the introduction may have been to reduce the extinction risk of the taxon, the occupied site is geographically close to the natural range, viable offspring have been produced, and at least five years have passed since the introduction.

Efforts to reintroduce the Schaal Whitefish to Lake Schaal by stocking with individuals from Drewitzsee have been underway since 2015, but it is unclear whether a reproductive subpopulation has become established.

This species' current population size and trend have not been quantified. The Lake Selent subpopulation was extirpated during the mid-20^th century and Lake Schaal is currently occupied by a hybrid subpopulation which does not resemble the native species in either a genetic or morphological sense (see 'Threats').

There is no evidence of any decline in the introduced Lake Drewitz subpopulation.

Lakes Schaal, Selent and Drewitz were formed after the last glacial period, and have maximum depths of 71.5, 36 and 31 metres, respectively.

The Schaal Whitefish feeds on zooplankton and benthic invertebrates. The annual reproductive period extends from November to December.

This species' extinction within its native range is understood to have been driven by anthropogenic eutrophication, plus introgressive hybridisation with the non-native Peipsi Whitefish (Coregonus maraenoides), which has been stocked in lakes Schaal and Selent since the late 19^th century.

Plausible future threats comprise the introduction of non-native whitefish species to Lake Drewitz, and habitat shifting, e.g., warming of the lake, due to climate change.

This species is likely to have been harvested commercially on a small-scale basis in lakes Schaal and Selent. A traditional fishery operates on Lake Drewitz, and the Schaal Whitefish is sold fresh and smoked as a local speciality. Recreational angling is also permitted on the lake, but neither activity is considered to represent a threat.

This species is included (as Coregonus spp.) in Appendix III of the Bern Convention and Annex V of the European Union Habitats Directive. Lake Drewitz lies entirely within the boundaries of a protected area which is included in the European Union's Natura 2000 network (site DE2440301). The resident subpopulation is actively managed for conservation purposes. Lake Schaal is located in the UNESCO Lake Schaalsee Biosphere Reserve, while lakes Schaal and Selent are both Natura 2000 sites (DE2331471 and DE1628491).

Efforts to reintroduce the Schaal Whitefish to Lake Schaal by stocking with individuals from Drewitzsee have been underway since 2015, but it is unclear whether a reproductive subpopulation has become established.