Researchers find two new freshwater pearl mussel rivers in one day

Researchers found two previously unknown rivers containing critically endangered freshwater pearl mussels in the Paatsjoki watershed in Inari in a single day, Yle reports. The discoveries were made during the Luonnonmetsät Sápmi project, and a researcher says they show that more undiscovered populations may exist in Finland.

The rivers’ names have not been made public. The mussels found in recent weeks were relatively young, and researchers do not yet know how large either population is.

Freshwater pearl mussels are difficult to spot in flowing water. Researcher Aune Veersalu said finding two rivers in one day was exceptional, noting that projects typically find two new rivers over their entire duration.

A population of more than 700 mussels was discovered in the Inari area last year. It was the only known population in the Paatsjoki watershed. That discovery prompted researchers to look more closely at riverbeds while working in the area.

Project coordinator Jarmo Pyykkö said the current work is a pilot study to identify rivers that could provide suitable habitat. He hopes funding can be secured for a wider survey, including rivers in old-growth forests.

Veersalu said young mussels have appeared in several rivers over the past 20 years, after a period when young specimens had not been found. She said the Paatsjoki watershed remains poorly studied and that further surveys should identify populations before human activity damages the rivers.

Freshwater pearl mussels have been protected in Finland since 1955. Touching them is prohibited without an exemption permit. The permits and supervision authority says the species requires special protection, and authorities can impose additional restrictions on its most important habitats. The mussel can also be grounds for conservation measures in Natura 2000 areas.