Oysters which used to flourish in a famous Highland waterway before being fished out over a century ago, are being reintroduced by the operators of a globally famous distillery which overlooks the Dornoch Firth.

The Glenmorangie plant near Tain in Easter Ross, is involved in an ambitious environmental project to restore long-lost oyster reefs to the firth, thought to have supported oysters for over 8,000 years until the 19th century, when they were fished to virtual extinction.

The producers of the famous malt whisky forged a partnership in 2014 with Heriot-Watt University and the Marine Conservation Society known as the Dornoch Environmental Enhancement Project (DEEP). As well as reintroducing the oysters it also aims to enhance biodiversity and act in tandem with the anaerobic digestion plant to purify the distillery's by-products created through the distillation process.

The re-introduction of the oysters to the Dornoch Firth comes as Glenmorangie officially opens its £5.2m anaerobic digestion plant.

This is expected to purify up to 95 per cent of the waste water that the Distillery releases into the Firth with the remaining 5 per cent of the organic waste naturally cleaned by the oysters.

Hamish Torrie, the distiller's director of corporate social responsibility, said: “Glenmorangie’s Distillery has stood on the banks of the Dornoch Firth for over 170 years, and we want to ensure that the Firth’s pristine habitat will be preserved and enhanced over the next 170 years.

“This restoration of oyster reefs in the Dornoch Firth, which is an internationally recognised special area of conservation, will help us realise our long term vision of a Distillery in complete harmony with its natural surroundings.”

Earlier this year, 300 oysters from the UK’s only sizeable wild oyster population in Loch Ryan, in south west Scotland, were placed on two sites in the Dornoch Firth. Over the next 18 months, they will be studied by Heriot-Watt University researchers with the aim of building an established reef within five years.

Dr Bill Sanderson, Associate Professor of Marine Biodiversity at Heriot-Watt, said: “Oyster reefs are amongst the most endangered marine habitats on Earth and it is thanks to Glenmorangie’s foresight and long term commitment that we can create a pioneering reef restoration project in the Dornoch Firth. It will take many years, but we have the ambition that the DEEP project is an example that could be replicated in other parts of the world.”

Marc Hoellinger, President and CEO of the company said the DEEP project went a long way to fulfilling Glenmorangie's ambition to be a fully sustainable business.

Calum Duncan, Head of Conservation Scotland for the Marine Conservation Society said “Active re-instatement of living seabed habitats such as oyster reefs can play a crucial role in ocean recovery, which is why we are delighted to be part of this partnership and look forward to a successful trial paving the way for larger-scale restoration.”

The overfishing of the the oyster has been commonplace around the world.