Scottish freshwater pearls’ fame was such that it is believed to have prompted Julius Caesar’s invasion of Britain. Be that as it may, PETER FROST decided to investigate.
Julius Caesar’s biographer, Suetonius, tells us it was admiration for the rare and beautiful product of a curious river creature known as Margaritifera margaritifera that led the Roman proconsul to invade what is now Scotland in 55BC.
Even in pre-Roman times the Scots had discovered that their clean, fast flowing rivers, burns and streams were home to a freshwater mussel that, as well as being a useful food source, sometimes hid a beautiful pastel-coloured pearl inside its rather plain shell.
Pearl fishing plays a rich part in Scotland’s history and culture. In the 12th century Alexander I, king of Scots had a vast pearl collection. The epic 14th-century medieval poem The Parl takes freshwater pearl mussels as its theme.
By 1355 Scottish pearls were being exported to Paris. Pope Pius II, on his visit to Scotland in 1435, named four main products that Scotland exported to Europe. They were hides, wool, salted fish and pearls.
The other better known Scottish export Uisge beatha, the water of life — whisky — wasn’t invented until around 1494.
The crown of Scotland (below) was first made for the 1306 coronation of Robert the Bruce and then enlarged and enriched for James V in 1540. It is of Scottish gold encrusted with rubies, diamonds, amethysts and large Scottish freshwater pearls.
As early as 1621 the Privy Council of Scotland issued a proclamation that all pearls found in Scottish rivers would become the property of the Crown.
By the 18th century pearl mussel populations were declining dramatically. This got worse up until the 20th century. In the 1970s, pearl mussels disappeared from an average of two Scottish rivers every year.
In the 1950s and early 1960s, poet, folksong collector and founder of the School of Scottish Studies, communist Hamish Henderson (below)
— the man who wrote the famous anti-apartheid protest song, Free Mandela — spent some summers travelling with and recording, the romantically named Summer Walkers.
He recorded the life, music and culture of these travelling people from the north-west Highlands, itinerant tinsmiths, horse-dealers, hawkers and pearl-fishers who made their living on the road. They are indigenous Gaelic-speaking Highlanders with a vital and ancient culture.
Along with film maker Timothy Neat, Henderson produced a book and a documentary film that are still the best description of this fascinating little known chapter of Scottish rural life. The book The Summer Walkers is still in print, the film is harder to find but is still screened occasionally.
Today the freshwater pearl mussel (Margaritifera margaritifera) is one of the most critically endangered molluscs in the world. They are similar in shape and colour to the better known farmed saltwater mussels you can buy in your supermarket or fishmonger.
The freshwater species however grow much larger and live far longer than their marine relatives. They can live for more than 120 years, making them one of the longest-lived invertebrates. They can grow as large as your hand and are dark brown to black in colour.
They live at the bottom of clean, fast-flowing rivers, where they can be completely or partly buried in coarse sand or fine gravel. They feed by drawing in river water and filtering out fine food particles. Each day an adult is able to filter more water than we use taking a shower. This is why they are so sensitive to water quality.
They have a complex life cycle and in their first year the tiny juveniles are often gobbled up by salmon or trout. Instead of being digested they migrate into the fish’s gills where they live for a year or more benefiting from the flow of oxygen passing through the gills. This symbiotic arrangement does not harm the trout or salmon in any way.
These mussels are an important part of our native biodiversity. Scotland has more than half of the world’s population. There are also a very small number of colonies of freshwater pearl mussels in Wales, probably just one in England and a few in the north of Ireland.
Over the last century they have disappeared from more than one third of rivers they used to inhabit. A further third of water courses now only contain old mussels with no sign of reproduction and young.
This paints a worrying picture of our rivers’ deteriorating water quality and the need for urgent action. The responsibility for river water quality and the wellbeing of Scottish mussels rests with the Scottish Environment Protection Agency (SEPA). Pictured searching for healthy mussels below.
As well as the threat from river pollution there is another much more direct threat to the species. Although fully protected by law since 1998, there is still a large amount of illegal fishing for the very valuable pearls.
Searching for pearls can only be done by opening and therefore killing the mussels, some of which will be over a hundred years old. Thousands of mussels may be destroyed in order to harvest just a few pearls.
Given the freshwater pearl mussel’s place in Scotland’s cultural history it is crucial that the final chapter in that history is not total extinction.
Schemes in some Scottish rivers and in the north of Ireland are having some success consolidating populations by transplanting younger mussels into existing colonies. The mussels seem to do better in concentrated groups with a range of young and old mussels growing together.
Illegal harvesting — pearl poaching as it’s known — is still a major threat to their survival.
Three quarters of known sites have suffered significant and lasting criminal damage.
A police raid on a Glasgow jeweller found a sizeable stock of illegally poached pearls.
The police and Scottish Natural Heritage have a campaign to protect the species.
They are asking the public to report any suspicious activity. As so often, we must not allow greed and the relentless scrabble for profit to make our countryside a less desirable place.
Scottish pearls can make pretty jewellery but that isn’t ever worth losing an ancient and fascinating species from Scotland’s beautiful rivers.
This article first appeared in the Morning Star 23 September 2016.