The taxonomic status of an unidentified and potentially conspecific whitefish subpopulation inhabiting Lake Wolfgang (de. Wolfgangsee) in Austria is in need of clarification.

In some published literature, the Austrian Whitefish 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 Austrian Whitefish is endemic to Lake Atter, Austria. It has a restricted range, with an extent of occurrence (EOO) of c. 66 km², which meets the threshold for the Critically Endangered category under Criterion B1 (EOO < 100 km²). It is present at a single location and the quality of habitat is estimated to be undergoing continuing decline.

Therefore, this species is assessed as Critically Endangered under Criterion B (B1ab(iii)).

This species is endemic to Lake Atter (de. Attersee) in the Salzkammergut region, upper Danube River system, Austria.

This species' current population size and trend have not been quantified. There is evidence of significant decline since the mid-20^th century, and only a small extant population is understood to remain (see 'Threats').

Lake Atter is a perialpine, oligotrophic lake formed after the last glacial period. It has a maximum depth of 169 metres, and is connected to adjacent Lake Mond (de. Mondsee) via the inflowing Seeache River.

Current knowledge suggests that the Austrian Whitefish predominantly occupies the profundal zone (c. 80-120 metres depth), where it feeds on zooplankton. The annual reproductive period is believed to take place in late December.

This species is possibly threatened by resource competition and/or introgressive hybridisation with non-native whitefish from the Baltic region that have been routinely introduced to Lake Atter for decades, although this may be precluded by reproductive isolation due to its profundal habitat preferences.

Other whitefishes that are native to the Salzkammergut region but putatively endemic to individual lake systems may also have been introduced to the lake. These include the Lake Traun Whitefish (Coregonus danneri) plus lineages inhabiting lakes Fuschl (de. Fuschlsee), Wolfgang (de. Wolfgangsee) and Hallstatt (de. Hallstätter See). Some or all of these are reared by a number of local hatcheries and referred to collectively as "Coregonus sp.", "Salzkammergut Reinanke" or "Renken". The possible translocation, hybridisation and introgression of these lineages has not been fully-explored.

Other non-native fish species, e.g., European Eel (Anguilla anguilla), have also been stocked in Lake Atter. The potential negative effects on native fishes, such as resource competition, predation or transmission of pathogens, have not been extensively investigated, although there is preliminary evidence that stocks of small-bodied fish species have declined.

Additional threats include water level regulations, degradation of littoral habitats for urban development and shifts in the temperature regime of Lake Atter due to climate change.

The lake became increasingly eutrophic due to human activities during the mid-20^th century, and this process plausibly drove a reduction in abundance of the Austrian Whitefish population due to deoxygenation of the profundal zone. It is not currently considered to represent a threat (see 'Conservation').

The species is not used or traded. It may occasionally be landed as bycatch, since a commercial fishery targeting the congeneric Lake Atter Whitefish (Coregonus atterensis) and non-native Maraena Whitefish (Coregonus maraena) operates on Lake Atter.

This species is included (as Coregonus spp.) in Appendix III of the Bern Convention and Annex V of the European Union Habitats Directive. Lake Atter is located entirely within the boundaries of a protected area that is included in the European Union's Natura 2000 network (site AT3117000).

Investment in wastewater treatment facilities since the 1970s has driven an improvement in the water quality of Lake Atter, which has returned to its former oligotrophic state. Regular monitoring efforts are carried out by the Institute for Aquatic Ecology and Fisheries Management, located at Scharfling near Lake Mond.

This species is not well understood, and research investigating its abundance, population trend, life history and response to the ongoing threats is strongly recommended.

The taxonomic status of the whitefish subpopulation inhabiting Lake Wolfgang is also in need of clarification.