The Courier & Advertiser (Fife Edition)
Crowning glory
Freshwater pearl mussels are “important to Scotland both culturally and ecologically” and we can help to ensure their survival
It has an incredibly complex lifecycle, can live for more than 100 years and is able to filter more water each day than is used in an average shower. It is reputed to be one of the reasons why Julius Caesar invaded the British Isles and its fragile ecology has today made it one of our most threatened creatures.
It may appear to be a rather unremarkable looking mollusc, yet the freshwater pearl mussel commands a pivotal place in our cultural history and has been at the centre of a major conservation campaign in Scotland to prevent it sliding into extinction.
Caesar coveted the rich pearl mussel beds found in our clear flowing rivers, and they have been prized for generations since, with the earliest reference to Scotland dating back to the 12th Century when Alexander I, King of Scots, was said to have the best pearl collection of any man living.
And, of course, locally-sourced pearls are embedded in the Scottish crown jewels. But as the exploitation continued, so the population of freshwater pearl mussels dwindled, and by the 20th Century they had become extinct in many of our rivers. As well as over-fishing, this massive decline was further fuelled by pollution and engineering works in rivers.
Over the last 100 years, more than a third of Scotland’s rivers which used to support freshwater pearl mussels now no longer do so.
Thankfully, in Courier Country, the Rivers Tay and South Esk still retain fragile but important populations, with the main strongholds lying in the north-west Highlands.
Dr Iain Sime, an ecologist with Scottish Natural Heritage (SNH), tells me that we have a very special responsibility to look after our surviving colonies, given that Scotland now supports some of the largest remaining functioning populations in the world.
Although now fully legally protected, these surviving remnants are still extremely vulnerable from unscrupulous exploitation by pearl fishers, as well as water pollution, nutrient enrichment and siltation.
Of crucial importance to their survival is the presence of brown trout and salmon, which the pearl mussel is totally dependent upon because, in the first year of their intricate lifecycle, the larvae live harmlessly on the gills of these fish.
SNH, working with other partners such as fisheries trusts and the Scottish Environment Protection Agency, as part of the Pearls in Peril initiative, has been co-ordinating and implementing a series of projects to help save the pearl mussel.
This has included improving water quality and river habitats.
Dr Sime is reasonably optimistic about the future of the pearl mussel in Scotland, but says we can all play an important role in ensuring its survival by keeping a watchful eye out for illegal plundering activities, with the species now a UK wildlife crime priority.
“The freshwater pearl mussel is important to Scotland both culturally and ecologically,” he says. “They are excellent environmental indicators and their presence in a river is a sure sign that it is clean and healthy.”