After the project Salmon and Trout in Klarälven, Fortum and Karlstad University decided to continue the research collaboration. The hydropower plants are a migration barrier for fish, both upstream and downstream. Within the new collaboration the aim is to investigate how fish migration downstream can be improved, an issue that has been quite neglected, not only in in Klarälven but in many other places in the world. A historical survey shows a sharp decline of salmon- and trout populations in the river already during the 19th century. After the construction of hydropower in Sweden in 1907, the quantity decreased to critical levels. However, the trend has been the opposite for wild fish, and the fishing quality in lake Vänern has vastly improved in comparison with the 1960s.
Description of the project
The continued research mainly aimed at increasing survival rates among smolt and kelt upon their return to lake Vänern from the spawning and growth areas. The total budget to increase the salmon’s chances of survival amounted to approx. 9 million SEK over a period of four years, 2012‒2015. The project was mainly financed by the Fortum Environmental Fund, and the Research and Development. Karlstad University also partly financed the project. The InterReg-project “Free migration of the Väner-salmon” (“Vänerlaxens fria gång”) is also a contribution to the studies at the University, which was concluded in a separate agreement.
The main aim was to find a long term and (cost-) efficient solution to get downstream migrating salmonids from the spawning- and growth areas in the upper part of river Klarälven to lake Vänern.
The project consisted of four parts:
- Projecting of measures for improved downstream migration.
- Hydraulic measures taken of flow conditions upstream at the hydropower plant Edsforsen, to highlight motion of fish and potential measures.
- Mapping the behavior of spawned fish and their chosen routes when approaching Edsforsen.
- Study the smolt behavior before different types of hydraulic conditions (e.g.. different forms of acceleration and turbulence in a controlled environment).