Freshwater pearl mussels planted in Ähtävä, Finland, in conservation effort

In Ähtävä, Finland, approximately 3-4 centimeters long freshwater pearl mussels, known as “raakku,” were planted on Wednesday. These are the largest specimens ever introduced in Finland, having previously been planted at under one centimeter in size. About a thousand juvenile pearl mussels have grown for five years in gravel boxes at the Konnevesi Research Institute in Jyväskylä, which has been working on conservation efforts since 2016. The future of this endangered species partly relies on this only facility in Finland dedicated to their cultivation.

Efforts to sustain the pearl mussel populations in the Ähtävänjoki and a few other rivers have been supported by Life projects. However, suitable river and stream habitats for the species have significantly dwindled nationwide, with estimates suggesting there are about 150 rivers left that can support the mussels, and only in about ten of these do new generations thrive. In the Ähtävänjoki and many other rivers, increasing nutrient and sediment loads worsen the living conditions for the mussels. Additionally, hydroelectric dams block salmon, which are critical for the pearl mussels’ reproduction, from reaching Ähtävänjoki.

If the young mussels survive, it could offer a century-long window to restore the Ähtävänjoki so that the mussels can reproduce naturally. The pearl mussel, categorized as extremely endangered since 1955, is a vital umbrella species, capable of purifying up to 50 liters of water daily through its gills, creating a favorable habitat for many organisms. It is also a strong indicator species; if mussels are present, other species are likely to thrive as well. The oldest specimens found have been recorded at 280 years old.

Conservation efforts continue across various projects, including the Life Revives initiative, which aims to improve habitats through river restorations, enhance mussel farming, and raise awareness about their preservation.