Waiting for the new field season,  a look back at the 2025 field season

The field work of the University of Jyväskylä team included planting young FPM in their home rivers. Some of the juveniles were brought directly from captive breeding rearing, while others had already spent a couple of years in box rearing in the river. Redox measurements and nail tests were carried out to determine the oxygen situation, both in connection with the planting and as part of the project's restoration monitoring measures. The summer fieldwork also included monitoring the density of salmonids by means of electrofishing.

Heavy rainfall and subsequent flooding hindered the University of Tartu's fieldwork. They also used a new measuring device to monitor the restoration work.

Riigimetsa Majandamise Keskus (RMK), the Estonian State Forest Management Center, built a new building on the banks of the river. The project can utilise it in its operations. They had an efficient field team, and the restoration was done by hand and with machines.

The work carried out by the Southwest Finland Centre for Economic Development, Transport and the Environment was located on the Karvianjoki River. Adult FPM were sought out in the river and grouped together to increase the likelihood of reproduction, so that juvenile production would increase naturally. The size and growth of the box-reared juveniles were checked in August. Restoration structures were repaired and new methods were tested.

CABN, the Norrbotten County Administrative Board, carried out restoration work on several rivers in northern Sweden. The work carried out in the summer of 2025 included e.g. restoring rapids by adding wood and stones to rivers, and restoring dry riverbeds. They also built spawning grounds for salmonids, as the freshwater pearl mussel lives on the gills of salmonids during its larval stage.

Metsähallitus Parks & Wildlife Finland worked on sites in northern Finland. Since the freshwater pearl mussel (FPM) is a sensitive species, particular care was taken when  planning and implementing work in areas where there are large numbers of FPM. Before beginning restoration work each day, the stream bed was checked over a distance of several tens of meters for FPMs. In areas with many mussels (tens/hundreds), no restoration work was carried out on the stream bed. Restoration measures were carried out in areas with a lower density of mussels or without them. During the restoration, the cleared rapids and riffles in the streams were restoned and wood was added to the streams to diversify the flow conditions and depth variation and to flood san away. They also created spawning grounds for trout and kindergartens for juvenile (young) FPM. Additionally, they blocked forest ditches. The effects of previous restoration measures were also monitored during the summer. Here as example of their amazing work is the restoration of Pölkkänänkoski rapids. As you can see in pictures 19 and 20, the river no longer resembles a log chute. It has returned to its natural state, providing much better conditions for freshwater pearl mussels.

The Pirkanmaa Centre for Economic Development, Transport and the Environment carried out river restoration work and built wetlands and pipe dams. The really cold weather in June and the heat in July made fieldwork difficult, but they did not give up and managed to complete everything that they had been planned for the summer of 2025.