A part of our team participated in a river restoration at the Lohioja river (“salmon brook”) on the 8th of August, which is located near Sajo and close to the Teijo national park. We were redesigning the river beds in order to create an ideal spawning ground for the endangered brown trout.
“The brown trout population is especially endangered in Finland”, Janne Tolonen, water specialist at Valonia, told us. In the deep rivers, it can’t find a suitable place to spawn anymore. In addition to that, the stock of brown trout decreased rapidly due to fishing. Not only at Lohioja river, but also at Halikonkoji waters, there are only very few trout left.
Around 25 people took part in the restoration, four of our team represented EKOenergy. The background of participants was diverse: from environmental activists to people that never took part in such an environmental project. We had a lot of fun, despite the large and very aggressive ants that wouldn’t stop attacking us and not to forget the huge number of mosquitos.
“Through a restoration project, the fish stock can be rebuilt and the biodiversity can be restored”, Jussi Aaltonen, also water specialist at Valonia, explained. Because trout tend to crawl in rocks and search for shelter we filled up the river with stones and branches. Through the created shallow riverbed trout can easily find a place to spawn and their fry can grow up safely. “The technique is simple – Jussi Aaltonen said -, try to make it look natural. If someone comes in 15 years and does not notice there is some man-made action, that would be our success!”.
Streams are becoming endangered habitats for all organisms living in them. In former times, rivers naturally transported rainwater and meltwater from the mountains and fields to the sea. Over the years the farming and forestry increased and farmers started to dig rivers and stream deeper in order to dry their fields. Because of that, the rivers have sometimes developed into deep canyons, which led to a decrease of the fish stock and other organisms.
Rivers are not only important for the biodiversity, as they do increase the diversity of the landscape, but also valuable for the people. They serve as recreation areas and are great for fishing.
A lot of projects aim to rebuild the biodiversity of the Finnish rivers, like restorations at the Vantaa river and projects in the areas of Perniö and Halikko. “We will come back to Lohioja during fall, the spawning time, and observe the trout”, Jussi Aaltonen said. If the restoration is effective, perhaps even fishing will be allowed again. Previous river restorations similar to this one were successful, so at EKOenergy we are hopeful they will be replicated in other countries.
Written by Amelie Oheim
Posted on 16 August 2018