In some published literature, this species is treated as an anadromous form 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: Least Concern (LC)
EU 27 regional assessment: Least Concern (LC)

Although this species' population trend may be decreasing due to habitat degradation, there is no evidence that the rate of decline approaches the minimum threshold for Vulnerable under Criterion A (≥ 30% over the longer of 10 years or three generations). It does not approach the range thresholds for Vulnerable under Criterion B (extent of occurrence (EOO) < 20,000 km², area of occupancy (AOO) < 2,000 km²) or D2. The population size far exceeds 10,000 mature individuals, hence it does not approach the thresholds for Criteria C or D. There exists no quantitative analysis which would permit application of Criterion E.

Therefore, the Maraena Whitefish does not currently meet the thresholds for any Red List criteria, and it is assessed as Least Concern both globally and for the EU 27 member states.

This species is native to the Baltic and eastern North Sea basins in northern and western Europe.

It is present throughout the Baltic basin, whereas in the North Sea its range extends southward from the eastern coast of the Skagerrak Strait to the Ems River system in northwestern Germany.

Numerous inland subpopulations exist, with notable examples including Lake Miedwie in northern Poland, lakes Vänern, Vättern and Mälaren in southern Sweden and Lake Ladoga in the northwestern Russian Federation.

It has been widely translocated to other locations both within and outside its native range, including parts of the Rhine and upper Danube river systems in Central Europe.

An accurate depiction of this species' current range is precluded by a combination of taxonomic disagreement throughout the published literature, imprecise reports of subpopulation decline/recovery and extensive artificial stock enhancement. The distribution map accompanying this assessment is therefore intended to act only as a basic guide, with no attempt to highlight the scope of its presence within individual river systems or indicate areas where natural subpopulations may no longer exist.

This species' population size is unknown, but it significantly exceeds the minimum threshold for Red List criteria (< 10,000 mature individuals). The current population trend has not been quantified, and the number of subpopulations is unclear.

It has declined significantly throughout its range since the mid-20^th century. In 2013, a decline of 40-80% within the previous three generations (c. 27 years) was estimated for the Baltic Sea basin.

In contrast, stocks are reported to remain relatively stable in the southwestern Baltic Sea, and recent increases have been reported in both Denmark and Sweden.

This species is mostly anadromous, occupying brackish and marine coastlines and migrating into the lower reaches of rivers during the annual reproductive period. In addition, a number of landlocked subpopulations inhabit deep freshwater lakes.

It is primarily benthivorous and feeds on crustaceans, molluscs and other macroinvertebrates, although larger individuals also prey on small fishes.

Individuals become sexually mature at age 3-5+, and some females spawn only every second year. Anadromous adults enter rivers when water temperatures fall below 10°C, e.g., from midsummer to October in the northern Baltic Sea and November in the southern Baltic Sea. There ie evidence to suggest that those migrating earlier differ genetically from those migrating later, e.g., the Torne River, Finland.

Depending on location, spawning occurs from October to December and coincides with water temperatures falling below 6°C. The gametes are released in shallow riffles, small tributaries or over firm sediments in lowland rivers and estuaries. Spent individuals overwinter in the lower reaches of rivers or at sea close to estuaries. Lacustrine subpopulations, e.g., Lake Vänern, spawn at depths of 8-20 metres in areas with firm substrata.

The demersal eggs hatch in early spring, e.g., from March to April in the Oder River (Germany and Poland), or at surface ice breakup further north, and drift downstream to the sea or tidal bays. Juveniles initially remain in these habitats before migrating to the sea during the summer.

In the Bay of Bothnia, adults may migrate up to 700 kilometres from their spawning grounds to forage at sea, and in general the northernmost stocks undertake the longest migrations.

This species' decline is believed to have been driven by reduced reproductive success due to habitat degradation, coupled with excessive commercial harvesting and the effects of climate change.

In particular, many foraging, nursery and spawning sites have been degraded by anthropogenic eutrophication and other forms of pollution. Intensive agriculture and wastewater discharge have driven high nutrient loads and benthic oxygen deficiencies in the Baltic Sea since the 1950s, and there is evidence to suggest that the coastal areas inhabited by the Maraena Whitefish have been more affected than offshore habitats.

Increased rates of algal growth and sedimentation linked to eutrophication are believed to impair the survival of Maraena Whitefish eggs.

Furthermore, this species' migration routes have been obstructed by canalisation of river channels or construction of dams and other barriers, restricting access to many of its preferred spawning sites.

Hybridisation with commercial whitefish strains, some of which are introgressed with non-native congeners, is also likely to be be reducing the fitness and genetic diversity of native subpopulations.

Warming of the Baltic region due to climate change has reduced the extent of winter surface ice and altered the timing of its annual melting. Ice cover is thought to prevent whitefish eggs from being transported to unfavourable locations or damaged physically by wind-generated wave actions in addition to reducing sedimentation processes. The movment of surface ice can also aid in the removal of harmful sediments, algae and macrophytes from littoral nursery habitats.

This species is fished commercially and marketed for human consumption, particularly in the northern Baltic Sea (Finland and Sweden) and to a lesser extent in Russia, the Baltic states, Poland and Germany.

Artificial stocking programmes to supplement wild subpopulations have been in place since the 1980s and 1990s. Gametes are stripped from wild individuals and the larvae reared under hatchery conditions, before juveniles are released into rivers and estuaries or directly into the Baltic Sea, e.g., in Finland c. 30 million fry and 4-8 million fingerlings are released annually into the Gulf of Bothnia.

Regular stocking at a more limited scale also takes place in Sweden, Estonia, Latvia, Russia (Kaliningrad), Poland and Germany.

This species is included (as Coregonus spp.) in Appendix III of the Bern Convention and Annex V of the European Union Habitats Directive.

It has most recently (2013) been assessed as Endangered in the Baltic Sea basin by the Baltic Marine Environment Protection Commission (Helsinki Commission, HELCOM).

At the national level, it is currently assessed as Least Concern in Denmark (2018), Least Concern in Sweden (2020), Very Rare in Germany (2023), Endangered in Finland (2019) and Vulnerable in Lithuania (2021).

Within the framework of artificial stocking programmes, some attempts have been made to maintain separate broodstocks corresponding to recognised subpopulations, e.g., Germany, Poland.

In the southern Bay of Bothnia, Sweden, there is an annual closed season extending from October 15^th to November 30^th. A smaller no-take zone was also established from 2011-2016, with a subsequent local increase in whitefish abundance.

The trophic status of the Baltic Sea is showing signs of improvement as a result of long-term international efforts to reduce the input of nutrients through more efficient wastewater treatment and reduced point source loadings.