The stone was found on the banks of the River Don in Dyce, Aberdeen, after the spell of warm weather lowered water levels and exposed the ancient relic.
The fisherman alerted Aberdeen University to the find with archaeologists then confirming that he made a “very significant find”.
The Class I Pictish symbol stone feature carved symbols including a triple disc with cross bar, a mirror, and a notched rectangle with two internal spirals.
It will further enhance understanding of the lost kingdoms of the Picts found in the east of Scotland between the 6th and 8th Centuries AD.
The stone was removed by a team from Historic Environment Scotland (HES), Aberdeenshire Council and The University of Aberdeen.
Bruce Mann, local authority Archaeologist for Aberdeen and Aberdeenshire, said: “The exceptional summer has led to river levels being at their lowest for decades, so there was always a chance that something new would be found. However, I certainly didn’t expect a find as stunning as this.
“Pictish symbol-stones are incredibly rare, and this one, with its apparent connection to the river, adds further to the discussions around their meaning and what they were used for.”
Pictish symbol stones are among Scotland’s most distinctive monuments.
Their elegant and vivid symbols and images can be found carved into boulders and slabs of rock, and on specially cut and shaped free-standing stones.
Class I Pictish stones date to between 6th to 8th Centuries AD, and are typically unworked stones with carved symbols.
The meaning of the symbols is debated, but it is believed they may represent the names of individuals or groups.
This new discovery is one of a number of impressive finds in the north-east of Scotland, which include an early Pictish stone now on display at the Church of St. Fergus, Dyce, close to where the new find was unearthed.
Kirsty Owen, Deputy Head of Archaeology at HES, said: “We’re very excited by this find, made all the more remarkable by the brief window of opportunity we had to recover the stone before the water levels rose again.
“AOC Archaeology, our emergency call off contractors, worked with a specialist lifting company to carefully and safely remove the stone from the river.
“This is a wonderful example of a local authority, university, national body and commercial archaeological company working together to save a significant piece of Scotland’s archaeological heritage.”
The Picts are one of Europe’s ‘lost people’, chiefly known for their elaborately decorated memorial stones found throughout eastern Scotland, from Shetland to the Firth of Forth.
Gordon Noble, Head of Archaeology at the University of Aberdeen, is currently leading a major research project into the early medieval Kingdoms of northern Scotland and Ireland.
He said: “The distinctive set of symbols carved into the stone meant we were quickly able to identify it as belonging to the Pictish tradition.
“Although there is a corpus of more than 200 of these stones across Scotland, each one is unique and this is a fantastic example which enables us to fill some of the gaps in the record and helps us to trace the development of literacy in north-east Scotland. As such, it is a very significant find.”
The Lord Provost of Aberdeen, Barney Crockett, said: “This is a fantastic find and another great offshoot of the marvellous summer we have been enjoying. The Pictish symbol stone is yet another example of how lucky we are in Aberdeen in having such amazing history on our doorstep”.
The stone has now been reported to the Crown Office’s Treasure Trove Unit, and temporarily moved to Edinburgh while discussions on where it will be permanently housed are ongoing.