River Göta älv south

The project includes three sub-catchments: Lärjeån, Grönån, Slereboånand Tidan. Favored species include salmon and pearl mussels, but also trout, asp, eel, burbot and crayfish. The area is also home to important bird species such as kingfisher, common tern and white-tailed godwit, as well as mammals such as otter.

Lärjeån has a high biodiversity, with 19 fish species

Grönån and Slereboån
Grönån and Slereboån in Ale municipality are part of the Göta River catchment area. There are habitats such as small watercourses, deciduous swamp forest and oak forest, as well as important species such as salmon and river pearl mussels.

Several red-listed and other important species live in the water system, including pearl mussels, crayfish, trout, eels and salmon. The green eel salmon is genetically unique. Other species such as minnow, asp and ferret are present, and white-tailed godwit and common tern breed in the area. Recruitment of river pearl mussels is weak. The watercourses have been cleared historically, but some parts have been restored.
Three migration barriers in the lower Slereboån river affect fish migration, especially for weak-swimming species. A fish ladder makes it easier for salmon and sea trout, but further measures are needed at the upper obstacle.

Slereboån has previously been affected by acidification, but liming has improved the water chemistry. In Grönån, agriculture provides more nutrient-rich conditions, which has partly protected against acidification.

Re-established wetlands
The LIFE project aims to re-establish wetlands and improve the aquatic environment. Planned actions include removing migration barriers, restoring spawning beds for salmon, trout and river pearl mussels, and surveying fish fauna with e-DNA. Ditches will be plugged to keep water in the landscape. Biotope management also benefits deciduous swamp forests.

Through habitat restoration and improved connectivity, biodiversity is enhanced, improving the living conditions for fish and mussels and strengthening the Grönån-Slereboån ecosystem.

Lärjeån
Lärjeån, located in western Västra Götaland, is a 55-kilometer-long tributary of the Göta River with a catchment area of 119 km². Twelve kilometers of the river have Natura 2000 status.

The Lärje River has a high biodiversity, with 19 fish species, including salmon, sea trout, asp and burbot, as well as the critically endangered European eel. It is also home to the Natura 2000 species, the stone loach. The river pearl mussel is present, but its recruitment is low due to sedimentation, lack of host fish and two migration barriers near the Göta River outlet.

The area is also rich in birds as defined by the Birds Directive, such as the common merganser, red-throated diver, common woodpecker and common tern. Mammals such as beavers and five bat species, including the red-listed southern bat, have been observed.

Low flows and migration barriers
The water is affected by periodic low flows, which threaten the ecosystem. Two permanent migration barriers near the outlet fragment the river and impair ecological connectivity. As Lärjeån is a reserve water source, the barriers cannot be removed, but fauna passages will be built. In addition, restoration of drained peatlands in the upper reaches of the river is planned and within the Vättlefjäll Natura 2000 site, five hectares of wetland will be restored to improve water quality.

Spawning areas and mussel larvae
To strengthen the pearl mussel population, host fish will be infested with its larvae. Five spawning areas for salmon will also be created. The bottom substrate is planned to be mechanically cleaned to improve the habitat for mussels and fish.

The project’s combination of habitat restoration, hydrological restoration and improved connectivity will strengthen the river ecosystem, increase fish production and improve the conservation status of target species. The measures will have positive effects on biodiversity and water flow all the way down to the sea.

Tide

The main stem of the Tidal River extends 160 kilometers from its headwaters in Ulricehamn, Habo and Mullsjö to its mouth in Lake Vänern at Mariestad. The upper reaches, where the project activities are focused, are dominated by woodland, deciduous forest and agriculture. The river Tidan consists mainly of calm stretches, but there are rapids in the upper parts.
In the lower parts, large-scale agriculture dominates, which has caused eutrophication. The river is affected by small-scale hydroelectric power plants and old dams that impair ecological connectivity and habitat quality.
The area is of high value for birds and mammals, with species such as kingfishers, lesser spotted woodpeckers and common starlings, as well as the red-listed mustached bat and the otter, which is a priority under the EU Habitats Directive.

Weak stocks of river pearl mussel
The Tidan has a rich biodiversity, with spawning grounds for species such as asp, trout and zander. Reproductive stocks of trout are found throughout the water system. Weak populations of the pearl mussel occur in the upper parts and regeneration is low. In Ettak’s streams, the mussel has disappeared, and the project aims to reintroduce the species.

Host fish and mussels will benefit
The project includes an action plan that includes reintroduction of river pearl mussel in Ettak Natura 2000, restoration of edge zones in Nyckelås Natura 2000 and dam removal and habitat restoration in both areas. In parallel, a plan for hydropower plant impacts outside the LIFE IMPROVE project is underway.

The restoration of habitat, hydrology and connectivity is expected to improve water flows, habitat quality, biodiversity and fish production in the Tidan and wider Göta River system. The measures will benefit host fish for the river pearl mussel, such as trout, enhancing the natural reproduction of the species.