Several more projects for clearing the rivers are on the way in Finland but the most important for the landlocked salmon is the dismantling of the dam at the rapids of Palokki in Heinävesi.
The demolition of a single dam would release nine rapids and would free up to 1500 kilometers of waterways upstream from the dam for the Lake Saimaa salmon population, possibly rewilding it.
According to Matti Vaittinen, the water systems manager at the Centre for Economic Development, Transport and the Environment (ELY Centre) the Saimaa population has another problem besides just spawning grounds: “The Lake Saimaa population is apparently the most inbred salmon population in the world, so its reproductive success wouldn’t necessarily be good.”
Spawn
According to Vaittinen, after the removal of the barriers at the border and on the Russian side there were plenty of parent fish around but only a small area insufficient for any meaningful spawning. Things changed quickly after the removal of the first dam in 2021.
“Immediately during the autumn or end of the summer 2022, salmon and trout hatchlings were found quite well from Kangaskoski – and year after year there have been better densities there”, Vaittinen said.
This year in Kangaskoski the average densities for salmon, which are calculated based on electrofishing conducted in several locations in Hiitolanjoki every year, reached another record ranging from 200 up to 400 per are in the most populous test area.
“I’ve electrofished quite a bit. And from nowhere, not even any spring streams, have I found densities like that,” said Vaittinen.
Upstream from Kangaskoski, at the most recently released rapid of Ritakoski, the restoration was finished in 2023 after the salmon had already begun to spawn, so last year no hatchlings were found there.
Rapids
But the salmon find their way upstream quickly. This year the best test area already had a density close to 200 per are. Unlike the future of the Saimaa population, Vaittinen doesn’t seem worried about the salmon in the Hiitolanjoki river and he says that the restoration has clearly worked.
Besides yearly electrofishing, the ELY Centre has also installed a fish finder this year to observe the fish populations of Hiitolanjoki but the data hasn’t been analysed yet.
Before the removal of the dams, it was estimated that the yearly productivity of the area could be 5 000-11 000 hatchlings, which would double the total production of the landlocked salmon in the whole Hiitolanjoki river. And now it seems like that could become the reality.
“When the fish that hatched in Kangaskoski start ascending back to their birth rapids like they usually do, we should have an effect where year after year we should have more and more salmon”, Vaittinen estimates.
This author
Tommi Rinne is an upstart nature journalist form south-east Finland, who is happy to see positive change in his local region.