Scotch whisky partnership returns 100,000 oysters to the Dornoch Firth

The goal of the Dornoch Environmental Enhancement Project, known as DEEP, was to regenerate an oyster reef close to Glenmorangie's Highland home which had been fished to extinction over a century ago.

Pictured: Professor Bill Sanderson, DEEP lead scientist of Heriot-Watt University showing oyster growth (Image: JP Photography) The project’s first phase, led by Professor Bill Sanderson, trawled archaeological records, ancient literature and fisheries records, then sampled shell material, to show that oysters had existed in the Dornoch Firth up to 10,000 years ago – and that reintroducing them was feasible.

In 2017, 300 oysters from the UK’s only sizeable wild oyster population in Loch Ryan were carefully placed on two sites in the Dornoch Firth in ballasted bags, to confirm that they would thrive in the water. 

Researchers were 'delighted' to see a survival rate in line with their highest expectations – up to 86% on one site.

For the next phase of the project, waste shell from the scallop and mussel industry was placed in locations on the seabed, to form reefs for the oysters.

This helped to stabilise the sediment and allow the oysters to grow on top, mimicking the conditions in which the species would have grown before they became extinct in the Firth.

Initially, in 2018, researchers began placing a total of 20,000 oysters, grown by suppliers across the UK, on these reefs.

The scientists have gradually increased these numbers to 100,000 today, with the earlier oysters "visibly thriving" on the new reefs. 

Pictured: Professor Bill Sanderson, Lead scientist, Heriot-Watt University, Hamish Torrie, CSR Communications Director, The Glenmorangie Company, Calum Duncan, Head of Policy and Advocacy, Marine Conservation Society (Image: JP Photography)

Lead scientist, Professor Bill Sanderson of Heriot-Watt University, said: “When we began DEEP 10 years ago, it was amongst the first Native European oyster restoration projects in existence, so we have been trailblazing all the way.

"Today, when I dive to the sites, I’m delighted to see six or seven-year-old oysters, as big as my hand, and fish living among them – visually demonstrating the biodiversity value of our work so far.

"Now we are starting to scale up, until we reach critical mass.

"There are very few examples of restoration at scale in the marine environment.

"We believe DEEP will be an exemplar for other restoration projects around the world.”

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DEEP’s long-term goal is to build up to four million oysters in the next five years.

Spread over 40 hectares these oysters will "bring back a self-sustaining reef which once thrived in the Firth".

Researchers believe their existence will also double biodiversity within 10 years, 'transforming' the seabed community.

Head of policy and advocacy at the Marine Conservation Society, Calum Duncan, said: “We’re delighted to partner with this pioneering project to reintroduce native oysters to their rightful place in the Dornoch Firth. 

"With the climate and nature crises intensifying, efforts to restore lost ecosystems must accelerate. 

"However, such ambition needs to be done carefully, and DEEP has excelled in ensuring all native oysters are cleaned and returned to the beautiful Firth. Over the past 10 years, we’ve proudly shared the project’s story with locals and visitors.

"We’ve also recruited volunteers to help clean oysters, playing a key role in the project's visionary goal of creating habitat for more species, locking up carbon and improving water quality.”

Pictured: A DEEP boat in front of the Glenmorangie Distillery (Image: Charné Hawkes Photography)

The Dornoch Firth, on the banks of which Glenmorangie Distillery is located, is an Area of Outstanding Natural Beauty, a Site of Special Scientific Interest, an internationally important Special Area of Conservation, and a Special Protection Area.

The AD treatment plant is part of Glenmorangie's long-term commitment to protecting and improving these surroundings in which its distillery "will always be rooted".

Opened in 2017, the plant treats the distillery’s pot ale (the solids which remain after primary distillation), spent lees (residue from the spirit distillation) and washing water (the water used when cleaning the mash tun and washbacks).

This reportedly reduces the chemical oxygen demand of the water released into the Dornoch Firth by 98%.

Meanwhile, oysters filter water as they feed, soaking up nitrogen and improving the water quality, meaning that within a few years, established oyster reefs will account for the remaining 2% – ensuring that Glenmorangie’s organic by-product of distillation is entirely accounted for. 

Glenmorangie's president and CEO, Caspar MacRae said: “At Glenmorangie, we aim not just to protect our beautiful Highland world, but to enhance it for future generations.

"That is why we formed our groundbreaking DEEP partnership a decade ago. Of course, rather like whisky-making, restoration takes time.

"From the seed of an idea to restoring 100,000 oysters to the Firth, we have achieved much in 10 years.

"But there is still much more to do before nature takes over and transforms this reef into a fully biodiverse, self-sustaining ecosystem.”

For more information, visit the Glenmorangie website, here.