A NEW plan to save Britain’s rarest fish has been hatched by transplanting around 70,000 eggs into a remote Scottish loch.
Vendace, a small freshwater fish that has been an inhabitant of deep lochs and lakes in the UK since the Ice Age, died out in Scotland in the 1960s, leaving them clinging to survival in just two remaining lakes in Cumbria, England. The herring-like fish is thought to have fallen victim to competition from introduced species and also to deterioration in water quality.
However, thousands of vendace eggs have now been collected from Derwent Water in the Lake District and put into Loch Valley in Galloway Forest Park in the hope a new population of the critically endangered species will flourish.
Dr Colin Bean, freshwater policy adviser at Scottish Natural Heritage, said: “We have been hatching plans to try to establish some new populations in Scotland. Something had to be done quite urgently to establish a refuge for them. It made sense that as they were part of the native fauna of Scotland we should try to establish them here.”
Experts undertook a hunt for a suitable spot, which had to meet rules on transferring species set by the International Union for the Conservation of Nature. They focused on south-west Scotland, assessing all the lochs, but relatively few were deemed to be of high enough quality for vendace.
Loch Valley is not considered perfect because it had become very acidic in the past due to pollution, but was thought to have recovered enough to be worth a try. Monitoring will take place in three years to find out whether the fish have become established.
The new plan will add to a smaller trial release in the Scotland in the 1990s when eggs and newly spawned fish were introduced to Loch Skeen near Moffat. With initial surveys suggesting the population is doing well, the larger release has now been authorised.
The fish released into Loch Skeen had been collected from Bassenthwaite in Cumbria, the only remaining home for the species in the UK apart from Derwent Water.
“During the same period, it became apparent that vendace had been lost from Bassenthwaite, the site where Loch Skeen fish had originally been sourced over ten years previously,” said Bean. “So in this respect, the Loch Skeen translocation happened in the nick of time.”
However, a similar attempt to establish the fish in Daer Reservoir in South Lanarkshire, with 12,800 newly hatched fish, about 30,000 eggs and 25 adults, was a flop. This may have been due to the number of brown trout in the water.
A final site, called “Sprinkling Tarn”, in the uplands of Cumbria, has also been selected, and 134,000 eggs were introduced there in 2005. Another 30,000 fry were transferred in March last year. So far the project to save the vendace, which also involves the Environment Agency in England, has cost about £100,000.
Bean said it was money well spent because it was important not to let the species die out.
“It’s not as if they are doomed because of natural factors,” he said. “It’s because humans have introduced non-native species and deterioration in water quality.
“We are not trying to save something that would have gone extinct anyway. We are trying to save something that would not have gone extinct without the impact of humans.
“Vendace are one of the earliest fish colonisers to the UK and are worthy of the conservation action they have received thus far.”
Vendace, which grow to about ten inches long as adults, are one of the few fish that managed to colonise Britain at the end of the last ice age nearly 13,000 years ago, making them an important link to the last glacial period.
The fish has only ever been recorded in four places in the UK – Castle Loch and Mill Loch at Lochmaben, Dumfriesshire, and Bassenthwaite and Derwent Water in Cumbria.