Scientists fear the survival of a distinct species of brown trout, which has never been seen before and was only discovered in recent years, is under threat from non-native fish being introduced to pristine Scottish waters.

The rare trout, which could be a new vertebrate species for the UK, is one of four forms found in Loch Laidon in Highland Perthshire.

The same team of experts also detected three forms of Arctic charr in nearby Loch Rannoch, and similar diversity in Lochs Tummel and Ericht.

The freshwater fish are examples of evolution in action in Scotland since the last Ice Age 10,000 years ago, and reveal far greater diversity than previously suspected in some of the country’s most picturesque lochs.

Read More: The Telegraph 16 April 2019