Lakes provide last haven for vendace

Heritage of the wild

Vendace is probably the rarest and most threatened freshwater fish in Britain. It has only ever been found in four locations and now it is confined to two Cumbrian lakes, Bassenthwaite and Derwent Water.

So what happened to this silver, streamlined fish, once so abundant in its Scottish sites of Mill Loch and Castle Loch in Dumfries and Galloway that clubs were formed to fish for it, that it could have become the only vertebrate known to have been lost from Scotland in the second part of this century?

Vendace disappeared from Castle Loch after it was used to take the town's sewage effluent in the early part of the century, and from Mill Loch by the 1970s due to gradual nutrient enrichment (eutrophication) of the loch and associated increases in populations of coarse fish which prey upon vendace, its eggs and young. Similar processes threaten to wipe out the two surviving English populations.

Not surprisingly, the vendace numbers among the 116 declining or endangered British animal and plant species for which rescue plans have been proposed by a government committee.

Safeguarding the vendace's remaining natural habitats is the species' best chance of survival.

The British Isles offers only a few sites capable of meeting the fish's need for relatively cool and oxygen-rich water, so English Nature is concentrating its efforts on the maintenance of the two suitably deep lakes with clean inshore areas for spawning, each favoured by tens of thousands of the fish

Scottish Natural Heritage is looking into the feasibility of reintroducing the vendace to south-west Scotland, as close to the original localities as possible. It aims to restore a self-sustaining population to one of the Scottish lochs by 2005 and subsequently to a second if the first is successful.

Vendace typically live for up to six years, by which time they may have attained a length of up to 28cm, and feed off zooplankton. It is widespread in northern Europe, especially Scandinavia where it is the subject of significant commercial fisheries.

The fact that the remaining British vendace have never been heavily exploited by the fisheries, with implications for their population and genetic structures, means that they are of considerable international conservation value.