According to BBC Scotland scientists have said the discovery was hugely significant and could lead to future commercial production.
Forth oysters, once regarded as among the best in Britain, were wiped out through over-fishing in 1957.
But Stirling University scientists have discovered wild oysters in the firth which might be farmed commercially.
Dr Elizabeth Ashton of the University of Stirling's Institute of Aquaculture discovered the oysters at a secret location.
Scottish oyster production is now centred on Loch Ryan in the south west, but once it was the Forth that produced a plentiful supply.
Dr Ashton said: "The Firth of Forth was once the major oyster fishery in Scotland and at its peak produced over 30 million oysters a year and they were exported all across Europe."
'Extinct' Oysters Return to Forth
SCOTLAND, UK - Live oysters have been found in the Firth of Forth - decades after they were declared extinct in the area.
