The central Dutch city of Utrecht has introduced a “fish doorbell” at a river lock to help monitor fish migration during their spring journey to shallow spawning areas. The concept is straightforward: an underwater camera at the Weerdsluis lock streams live footage to a website. When viewers spot a fish, they can click a button to send a screenshot to the organizers. Once enough fish are seen, a water worker is notified to open the lock, allowing the fish to pass through.
Now in its fifth year, the initiative has gained a global following, with millions tuning in to watch this unique combination of slow TV and ecological awareness. While the footage is often just a murky green with occasional bubbles, more fish appear as the water warms up, offering viewers a glimpse of the fish on their migration.
Without assistance, native freshwater fish such as bream, pike, and bass can become trapped behind the lock, making them vulnerable to predators during the spring when the lock is seldom opened for boats.
The fish doorbell was created by ecologist and concept developer Mark van Heukelum. He has been pleasantly surprised by the widespread interest, with millions of people from around the world tuning in over the years.
“I think it’s the combination of a good cause, a captivating story, and a simple idea that draws all this attention,” said van Heukelum.
Anna Nijs, an ecologist with the Utrecht municipality, was equally surprised by the global popularity of the concept.
“We receive a lot of fan mail from people who enjoy it as slow TV and find it relaxing,” said Nijs. “They also appreciate that they can actually contribute and help.”
