It has existed on Earth for more than 400 million years. But today, the sea lamprey is one of Sweden’s most endangered fish species. In this video segment, we tag along on surveys in the River Ätran. Here, we find out how this rare fish is faring—and whether the conditions still exist for the species to reproduce in the river.
Video from the Stockholm River – New Hope for Salmon and Sea Lampreys
When the waterway was opened at Okome Mill in Stockån, fish were able to move freely upstream through the water system. Spawning salmon have been observed—and the restoration could have a major impact on the critically endangered sea lamprey, eel, and other species. Watch our video clip from our visit to the restored area.
New fish counter displays results instantly—eight species of fish have already passed through the River Råån
After the City of Helsingborg removed the Görarpsdammen dam on the River Råån in 2025, a new fish counter was installed upstream of the former dam. The removal has created unobstructed migration routes throughout large parts of the water system, and the counter is already showing that fish are beginning to reclaim areas that have long been inaccessible.
Strengthening Thick shelled river mussel stocks
In May, efforts to strengthen the populations of the threatened Thick shelled river mussel were launched. Through targeted measures in Vramsån, Bråån, River Bräkneån and River Mieån, the work has focused on facilitating the mussel’s natural reproduction – a method that can help strengthen and rejuvenate the populations. Read more
River Ätran restoration could save the sea lamprey
The sea lamprey is an ancient group of fish that existed long before the age of dinosaurs – but today the species is critically endangered. Migration barriers, habitat destruction and changes in the ocean have led to a dramatic decline. In River Ätran, extensive restoration efforts are underway to benefit the species, and in the middle of central Falkenberg, electrofishing is being carried out to locate larvae of the secretive fish.
New fish camera at Okome in Stockån shows life below the surface
We have now placed a fish camera at Okome in Stockån to monitor what is happening in the river. The camera is located upstream of the dam that previously constituted a migration barrier, but which was partially demolished in 2025. The measure was implemented to recreate more natural flows and enable free migration routes for fish and other aquatic organisms.
Inventory for juvenile sea lampreys
The endangered sea lamprey, which is a target species in the project, starts to migrate up from the sea to its spawning grounds in early summer. The first sea lamprey migrated up the River Ätran a few days ago to find a mate, and now we are eagerly awaiting more to ascend the River Ätran, which is its most important breeding water in Sweden.
How salmon make the journey to the sea
What happens below the surface is often a mystery. How do fish move through our rivers? Where do they stop – and why do some individuals disappear on their way to the sea? An exciting project in River Rönne å and Skälderviken is using acoustic telemetry to help researchers find answers to these questions.
New podcast – the secretive life of mussels
Now the spotlight is on two of our most fascinating – and threatened – underwater inhabitants: Freshwater pearl mussel and Thick shelled river mussel. Listen to the podcast as the experts talk about the unknown lives of these species, their dependence on fish, and how restoration is giving them a chance to come back.
Planning and studies
During the winter, not many water restoration measures are carried out in Sweden, instead, new upcoming measures are planned and designed. The measures planned within Improve Aquatic LIFE generally require some type of preliminary investigation before implementation. This is important to avoid negative impacts and to ensure that the measure achieve their intended effect.