River Nissan
Bogs and streams
There are 28 Natura 2000 sites in the Nissan catchment area, including the Komosse and Gagnaryds mosse raised bogs – both with high nature values. The Nissan tributaries Kattån and Sågån are also important watercourses for the host fish species of the river pearl mussel larvae, such as minnow and trout. Plugging of ditches, fauna passages and the enhancement of the hydrological status will improve the living conditions and production of fish and mussels. Species such as brook lamprey, eel, golden eagle, white-tailed eagle and common tern will also benefit in the area.
The project area is located in western Jönköping County and includes Kattån and Sågån, two tributaries of River Nissan that flow into Laholmsbukten. These watercourses are linked to the Komosse Natura 2000 site, a valuable marshland area approximately 13 km from Kattån and 8 km from Sågån.
The area also has high bird and mammal values, with species such as golden eagles, white-tailed eagles, white-tailed starlings and otters having been observed.
Kattån and Sågån
Kattån has a natural morphology but is in some places affected by rock clearing. The main challenge is the migration barrier at the Sågevik dam which negatively affects connectivity. The project plans to remove the dam or install fishways.
The Saw River has similar problems with rock clearing and a migration barrier. During periods of drought and low water flow, biodiversity is threatened. The project will remove migration barriers and adapt the outlet of Lake Elsa to improve water flow and drought resilience.
Fish, birds and otters
Both watercourses have moderate biodiversity with species such as trout, minnow and brook lamprey. The target species of the project are trout and eel. The pearl mussel is present in the water system but has weak reproduction, probably due to migration barriers and poor water quality.
The area also has high bird and mammal values, with species such as golden eagles, white-tailed eagles, white-tailed starlings and otters having been observed.
Natura 2000 site Komosse
Komosse is a nature reserve with extensive raised bog and swamp forest, which are important habitats for birds and aquatic species. In the past, some wetland restoration has been carried out in drained areas. In order to preserve the natural values, measures are required to ensure free migration routes and good habitat conditions.
Natura 2000 site Gagnaryds mosse
Gagnaryds mosse, located about 15 km southwest of Jönköping, is a protected raised bog with streams, laggkärr and wooded bog islands. The area is important for bird life, where species such as the little ringed plover, golden plover, green leg and crane nest. Previous land drainage has had a negative impact on the hydrology of the bog, and restoration measures are needed to restore the natural water balance.
The project will improve the ecological status
Through a combination of hydrological restoration and improved connectivity (dam removals and fishways), the project will strengthen the water regime of the ecosystem, improve habitats and increase biodiversity. The measures will benefit fish production and the conservation of the pearl mussel, contributing to the improvement of the ecological status of River Nissan and its tributaries.
Survival of river pearl mussels depends on host fish
Barriers to migration
Removing migration barriers and opening up the river pearl mussel’s host fish, salmon and trout, will increase the species’ ability to reproduce. Barriers to migration come in many forms, from natural to man-made dams and power plants. In some cases, a good solution may be to build a wildlife passage to allow fish and other organisms to bypass the migration barrier.
River Nissan
Latest news from the project area
Here you can read news about the target species and the actions being taken in the project area.