Exclusive, 12 September 2014
Millions of freshwater pearl mussels have been killed by sewage pollution of the River Spey in northeast Scotland over the last 15 years, according to scientific reports released under freedom of information law.
Experts from the James Hutton Institute in Aberdeen have revealed that the number of mussels in the river has halved from 10 million in 1998-9 to five million in 2013. They blame high levels of phosphorus and other pollutants in sewage discharges for the decline, along with other factors.
Freshwater pearl mussels, a globally endangered species that can live for more than 100 years, are among the UK’s most protected wildlife. They hide at the bottom of clean, fast-flowing rivers and have long been victims of illegal fishing for the pearls they sometimes produce.
But the mussels are also under threat from pollution, the scientists warn. In detailed draft reports for the Cairngorms National Park Authority in May and June, they argue that the environmental standards set for the Spey are far too lax.
Concentrations of phosphorus in the Spey "are generally too high and of greatest immediate concern,” they say. Standards under the European Union’s water framework directive "have been set considerably higher than they should be, possibly by 1-2 orders of magnitude”.