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Coregonus vandesius, the Vendace, is a freshwater whitefish found in the United Kingdom. Population surveys of this species since the 1960s have revealed a steady decline.

Biology[]

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.

Distribution and habitat[]

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. 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 which were depleting the lake's oxygen supply, but the plant was to be renovated in 2004 in order to prevent this.

Coregonus vandesius was introduced to Loch Skene in Dumfries and Galloway, Scotland, in the 1990s as an attempt at ex-situ conservation after the severity of habitat deterioration at Bassenthwaite was noticed. This has proved largely successful and Loch Skene now has nearly ten times more vendace per hectare than Derwent Water according to a survey carried out by the Centre for Ecology and Hydrology. Conservationists hope to reintroduce the fish to Bassenthwaite Lake once the habitat is restored.

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