Photo: TiVa.
Installation of the fish counter at Gamla Stan in Slussen. The new fish highway in Stockholm has some of the first fish passages between the Baltic Sea and Lake Mälaren at Söderström in nearly 400 years.
Today’s story is about how Sweden is giving a helping hand to migrating fish that are not strong swimmers.
TiVa, an AI-powered fish-counting company, reports, “In mid-2024, a TiVA FC was installed in connection to the newly built fish migration path at Slussen in Stockholm. This long-awaited passage allows fish to freely migrate between Lake Mälaren and Saltsjön at Söderström for the first time in almost 400 years. As part of the reconstruction of Slussen, a new fish migration path has been constructed under the northern sluice quay on the side of Gamla Stan. The old Nils Ericson sluice has been converted into a passage to facilitate the free movement of weak-swimming species such as eel, roach, and perch – species that were previously hindered by human infrastructure.
“The TiVA FC fish counter delivers [improved] results, both in image quality and AI-based species and length classification. … The TiVA FC at Slussen is connected to our cloud platform fiskdata.se. Here, data is available for both the client and, in this case, for the public. … The City of Stockholm has chosen to broadcast a live stream via TiVA’s YouTube channel. Shorter streams can also be broadcasted to other platforms, like Facebook, depending on the client’s needs.
“The City of Stockholm will install an informational screen for ‘Fish TV’ on the crane structure by the fish counter. Passersby in Gamla Stan will be able to learn more about the project, see selected videos, and get updates on the latest migrations.” More at the TiVa website, here.
And from Stockholm’s website: “You can watch online the fish swimming between Lake Mälaren and Saltsjön [at fiskdata.se].
“Moving between different areas is a natural part of life for many fish species. They migrate from their breeding grounds to spawning grounds to reproduce. When humans have blocked various watercourses, this has prevented fish species from passing through. To protect the fish and promote the environment, watercourses can be restored, or, as here at Slussen, a fish migration route can be opened up.
“The primary purpose of the fish migration route is to enable passage between Lake Mälaren and Saltsjön for [fish] that do not jump, which is basically all species except salmon and sea trout. By building this route, we hope that species such as eel, roach and perch will once again be able to pass here.
“The trail is designed by experts to mimic as natural an environment as possible. Stones of various sizes have been carefully placed along the trail. Some of the stones come from Gustav Vasa’s 16th-century defensive wall, which was found during the excavations of Södermalmstorg in 2022. The water flow needs to be calm so that the fish can stop and rest. There is lighting here so that the fish can swim in pleasant light.
“The fish walking trail is located under the quay on the Old Town side and is not visible from the outside. But you can watch the fish swimming through at fiskdata.se.” More here.
Looking for comments — from Swedes and fish lovers everywhere.
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