History and current situation

The Vuoksi River basin has been home to a number of brown trout populations, the majority of which have perished owing to water construction, among other reasons. In addition to migrating brown trout populations, the river basin harbours a trout species that spends its whole life in flowing water without ever migrating to feed in a lake.

To divide trout into species on the basis of migration behaviour is artificial. The two ecological varieties may reproduce together. Therefore, their migration behaviour is regulated by circumstances in addition to genetics.

tammukkaPhoto: A juvenile brown trout caught in a river

A large percentage of natural brown trout breeding grounds have been destroyed by dam construction, river cleaning and deteriorating water quality. The trout can also reproduce in small brooks with slow currents. A few of such undammed river areas are left in the Vuoksi River basin.

 

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Photo: Juuanjoki River flows into Lake Pielinen

Overfishing in lake and river areas diminishes trout populations to the extent that few individuals reach sexual maturity. In spite of the availability of potential natural breeding grounds, the natural reproduction rate of the brown trout is low, and the populations are practically dependent on fish stocking.

Fishing regulation, and breeding and nursery area rehabilitation are preconditions for securing natural brown trout populations.



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The project is co-financed by the LIFE+ -programme (EC)