Pearl Mussel

The freshwater pearl mussel (Margaritifera margaritifera) is a mussel species of clean rivers that is on the verge of extinction in Ireland and western Europe due to intensification of land use. European freshwater pearl mussel populations have declined by 90% over the past century. In Ireland, 27 freshwater pearl mussel populations are protected within Special Areas of Conservation (SACs). Eight of these populations contain 80% of the total Irish freshwater pearl mussel population and are known as the ‘Top 8 catchments’.  While the ‘Top 8 catchments’ have some of the highest remaining numbers of freshwater pearl mussels in Ireland, these populations are also undergoing a slow decline, and face extinction unless action is taken.

Dawros River

The main reason for this decline is the low level of survival of juvenile mussels, which are extremely sensitive to slight changes in environmental conditions. This is leading to an ageing population, not capable of replenishing itself. Juvenile survival is dependent on a clean, well oxygenated riverbed, with little silt, sediment, or algal growth.

In 2018, Letterfrack Tidy Towns through the Connemara Green Festival ran a mini conference on Freshwater Pearl mussel to highlight the vulnerability of this species. This species, which lives to 120 years is the oldest living species in Ireland. The Freshwater pearl mussel is sensitive to pollution and requires pristine conditions. We have two of the eight most important rivers for this species in Connemara; the Owenriff and the Dawros. This species is much maligned and yet it is on the verge of extinction with only one river nationally producing young. This is the Bundorragha river in Mayo.  The conference was well attended with farmers and other landowners attending and it served as a launch pad for the Freshwater Pearl Mussel EIP farm scheme locally.