Restoring migratory salmonid populations in regulated rivers in the northernmost Baltic Sea area, Northern Finland - biological, technical and social challenges

This paper summarizes the objectives, activities initiated and approaches used in developing Atlantic salmon stock re-building programmes in three large river systems in northern Finland in order to identify the priorities for research and management for further restoration and rehabilitation steps. Until recently, these historically renowned major salmon rivers have been harnessed for hydropower for 4060 years without provisions for fish passage. Hydropower companies are obliged to compensate for the losses caused by dam construction by annual fish releases, including juveniles of Atlantic salmon and migratory brown trout. Returning fish are harvested in the designated terminal fishery areas at river mouths. Recently, activities aimed at restoring salmonid stocks have started in all these rivers. First fishways at the dams closest to the river mouths were constructed on two rivers, and preliminary projects were completed to review the preconditions for restoration, options for bypassing the dams, and to study the performance of these fishways. New projects incorporating further detailed fishway planning are underway. The various projects have proved successful in bringing together authorities, hydropower companies, local organizations, and expertise from various institutions for a joint effort to tackle these multifaceted and multidisciplinary problems.