From BBC Future Planet
Three years ago, when construction workers started demolishing a series of dams on the Hiitolanjoki River in Finland, they were greatly surprised to spot a run of salmon. Part of the country’s last wild and landlocked population, the fish were returning to the river after years of absence. For Pauliina Louhi, it was a sign that the ecosystem’s recovery had begun.
“It was not only adults – there were many salmon juveniles,” Louhi, an ecologist at Natural Resources Institute Finland, a Finnish research organisation, recounts enthusiastically. “They had already been spawning on the lowermost part of the river. When I saw how the site looked after the dam removal, I actually had tears in my eyes.”
The river used to be a key migration route for the endangered freshwater salmon from Lake Ladoga, in nearby Russia, to Finland. But between 1911 and 1925 the introduction of three dams supplying hydroelectric energy created barriers between the salmon and their spawning grounds. The salmon and other fish, like brown trout, were trapped on the Finnish side of the river, which remained fragmented for 100 years.
Today, however, with the dams removed, the water runs freely once again through newly built rapids surrounded by tall trees. Every time a dam was removed, salmon “embraced” the new part of the river, says Hanna Ollikainen, executive director of the South Karelian Recreation Area Foundation, a civil society organisation, which acquired the dams and is responsible for the environmental and touristic development of the area. In 2021, after the first removal, five spawning nests were spotted; in autumn 2022, one year on, baby salmon reached a record breaking number of 200 fish per acre. When the removal of the upmost dam, Ritakoski, was completed in December 2023, they found a free passage to the upper parts of the river and its tributaries.
The removal of the three dams was the result of decades of work, which took into consideration not only the health of the river, but also the economic context, says Ollikainen. Evaluations concluded that their electricity production had become unprofitable for the power plant owners – especially when the costs of maintenance and mandatory environmental protections, such as fish-ladder introductions, were taken into account, Ollikainen says. So the dams were sold and dismantled.
Footnote: Full article is at https://www.bbc.com/future/article/20240229-why-europe-is-removing-its-dams
Have the public realised that with the fad for electric cars – probably short lived – and the need for renewable electricity, many salmon and trout rivers may be dammed?
Many species of freshwater fish, both introduced trout and salmon, and the majority of New Zealand’s native fish have a marine stage to their life cycle.
Most are anadromous spawning in freshwater, others like eels breed at sea.
Often the sum of the life stages require an intact river catchment due to differing water quality requirements for each stage.
Water quality parameters and water quantity can form barriers blocking migration just as effectively as dams.
High water temperatures and low river levels are barriers to salmon and trout migration, typical consequences of water abstraction for irrigation.
It is important to retain “environmental flows”.
Hydropower is not the only option for renewable energy. Solar energy is a good and more river friendly alternative. If we can do it in The Netherlands with way less solar exposure than in New Zealand, then surely it can be utilised here as well. Solar panels can be integrated in our roofs nowadays. Combined with some external batteries you could store the excess generated, charge your car, or even use your car battery as external storage and pump it back into the house. This is not fiction as it happens already in The Netherlands.
It seems to me that we are fast losing our last years of legal and corporate fights against river and environment destruction in the south, haven’t seen any other correspondence since reading Lan could well be an allie in our on going conservation battle.
This is a very interesting article and in my travels in Europe and USA I have seen the dismantling of dams and the reconstruction of rivers to their previous meandering ways.
With the fanatical fervour for fast tracking resource consents being rammed through by government ministers Shane Jones and Chris Bishop, the environment is up for exploiting just to feed the obsession with GDP.
Interesting reference to GDP by Ben Hope. Gross Domestic National Product is a shortsighted way to measure progress. It is based on consumerism and only economics. What is needed is a full culture shift to Genuine Progress Indicator (GPI) where economic is important and so are social and environmental factors.
Kate Raworth noted economist, wrote a very good book on the fallacy of GDP, called “Doughnut economics”. Messrs Jones and Bishop should read it, as should all MPs for that matter.