Coregonus vandesius
| Coregonus vandesius | |
|---|---|
 |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Actinopterygii |
| Order: | Salmoniformes |
| Family: | Salmonidae |
| Genus: | Coregonus |
| Species: | C. vandesius |
| Binomial name | |
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Coregonus vandesius (J. Richardson, 1836) |
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| Synonyms | |
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Coregonus gracilior |
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Coregonus gracilior
Coregonus vandesius, the vendace, is a freshwater whitefish found in the United Kingdom. Population surveys since the 1960s have revealed a steady decline and the fish is no longer present in some of its previous haunts but is still present in Bassenthwaite Lake and Derwent Water. The main threats it faces are eutrophication and the introduction of alien species of fish which eat its eggs and fry. The International Union for Conservation of Nature has rated its conservation status as "endangered".
Most authorities now consider Coregonus vandesius to be a subjective synonym of Coregonus albula, which is a more widespread North European freshwater whitefish species. Both taxa are also known by the common name vendace. The status however remains controversial, and FishBase still lists C. vandesius as a separate species, reflecting the recent treatment of the European freshwater fish fauna by Kottelat & Freyhof (2007). Another synonym of British C. vandesius is C. gracilior.
Coregonus vandesius inhabits deep, cold lakes, and uses planktonic crustaceans, such as copepods, as its primary food source. The fish does not migrate and has a life span of about six years. The species is now Britain's rarest fish.
The vendace has only ever been known as a native species at four sites in Britain: Bassenthwaite Lake and Derwent Water in the English Lake District, and the Castle Loch and Mill Loch in Lochmaben, Scotland. The species is thought to have died out at all of these sites except Derwent Water. The Castle Loch population disappeared in the early part of the 20th century, and the Mill Loch population disappeared in the 1990s. The fish has not been recorded at Bassenthwaite Lake since 2001, but was recently rediscovered in 2014. The declining populations of the fish are thought to be due to introduced species that utilise the native vendace as a food source, and also due to pollution. For example, a water treatment works near the lake had been overflowing with raw sewage at times of high water levels, causing severe algae blooms that were depleting the lake's oxygen supply, but the plant was to be renovated in 2004 in order to prevent this.
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