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Spawning in the heart of the city


A park is located in the middle of Oulu, where migratory fish spawn in the streams. That is a rarity on a global scale. This is thanks to good cooperation and the enthusiasm of the people of Oulu.

The next time you go to the Hupisaaret City Park, look deeper than the surface of its brooks. There you can find all kinds of fish, including salmon, trout, common roach, grayling, perch, pike, and common bleak. It is particularly interesting to follow the streams in the autumn, when after decades, at least trout come back to spawn.

"Nature will return when given a chance," says Tarja Väyrynen, director of quality and the environment at Oulun Energia.

Rare delicacies around the world

The City of Oulu, the Natural Resources Institute Finland, the Centre for Economic Development, Transport and the Environment of Northern Ostrobothnia, and Oulun Energia have given nature a chance on the Hupisaaret Islands. The brooks have been restored so that since 2018, migratory fish have been able to spawn again in the Hupisaaret Islands, which has been their natural breeding ground. In three years, there have been many good experiences, although the time span is still short.

"The various species in the streams are pleasingly diverse. The sea trout and the planted trout have both approved of the brooks,” says Pauliina Louhi, a special researcher at the Natural Resources Institute Finland. Louhi is also pleased with how interested the people of Oulu have been in the matter. She advises people to continue participating in renewal workshops and to follow the autumn spawning on site under the light of a torch or headlight.

"We have a well-managed city park in the middle of the city with spawning trout. There is hardly anything like it in other parts of the world,” says Louhi, who knows to say that the Hupisaaret Islands will be utilised even better in the future as a tourist destination.


Change in the spirit and thought of the time

Since 2018, Oulun Energia has led water to the Hupisaaret brooks all year round, instead of just summer watering. The water situation in natural streams deteriorated with the Merikoski power plant.

"Here we can see the change in the spirit and thought of the time. We are now questioning permanent structures and considering whether things can be done differently and whether the effects can be mitigated,” says Väyrynen. Väyrynen also talks about the big picture. She also adds two other important issues to the renovation of the Hupisaaret river basins: the Hartaanselkä fishing area and the Merikoski fish pass, which has made it possible for migratory fish to reach Oulujoki since 2004.

"It is exceptional that in the heart of a city the size of Oulu, there is the possibility for salmonids to swim upstream, their breeding area, and a significant fishing area. A similar combination cannot be found elsewhere in Finland."

The background is a vision of the Oulujoki water system, which examines the coordination of hydroelectric power and migratory fish. Under the council initiative, Oulun Energia is currently examining whether the old Merikoski river basin can be used as a breeding ground for fish, as it is now used as a drainage basin for flood waters. In cooperation with Fortum, the research will also be expanded.

"Cooperation enables the river basin to be viewed as a whole. We get important information about which potential sites, from the sea to Oulujärvi, are best suited for breeding,” says Väyrynen.

This article was originally published in Oulun Energia's customer magazine 2/2021. Text by Mari Siliämaa, photos by Kati Leinonen and Hauki Media.