How the Dutch Fish Doorbell helps migrating fish every spring

Ring the Fish Doorbell to help migrating fish navigate a Dutch canal

By KR Callaway edited by Andrea Thompson

In a canal in the Dutch city of Utrecht, fish begin to gather behind a lock called the Weerdsluis. Now, for the sixth year in a row, you can help them get the attention of the lock’s operators. The fishing doorbell—or Display doorbell in Dutch—is back.

Started in 2021, this project allows viewers around the world to monitor the feed from an underwater camera. When they see a fish that wants to move through the lock, they can ring the doorbell and alert the operators of the fin animal waiting outside.

“The project is a good mix of doing something for nature and for people to get involved and do something,” says Anne Nijs, an ecologist for the city of Utrecht and one of the creators of the Fish Doorbell.

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Many species of fish – including grayling, catfish, eel and pike – cross the Netherlands’ many waterways in the spring to reach the spawning grounds upstream. Even when aquatic creatures begin to fill the canals, ships are still sparse in early spring, and the locks that allow movement through the water are often closed. This creates an obstacle for migrating fish, most of which start their journeys around this time of year, when the water first starts to warm.

In Utrecht, until the lock’s gates are opened again, fish are stuck waiting nearby. For some, this means that one cannot reach the spawning areas in time to lay eggs under favorable conditions. And for others, it doesn’t mean escaping roaming predators.

Operators and municipal employees had long wanted a way to release fish through the Weerdsluis, or “weathered lock”, but it is not as easy as pushing a button. The lock dates back to the 17th century and requires operators to manually turn an iron wheel for between 30 minutes and an hour. Because it’s such a big commitment, the operators wanted a way to be sure there were fish at the gate. That’s when Nijs and ecologist Mark van Heukelum decided to give them a bell.

They placed an underwater camera on the lock. And every year since 2021, ecologists have live-streamed the footage to a website that allows people to tell lock operators when they’ve seen a fish trying to get through. Nijs and van Heukelum never expected the doorbell to become a worldwide exercise in social science.

“We put flyers in the streets about the Fish Doorbell because we were afraid that maybe no one would join, but … a lot of people joined, (and) more every year” have, says Nijs.

Last year, the site had more than 2.3 million unique visitors who pressed the doorbell a total of 200,000 times and allowed thousands of fish to continue their journeys.

Nijs says being able to ring the doorbell fills people with a “positive feeling” and many people have told her about the calming effects of watching the canal’s fish. But the biggest benefit has been for the fish themselves. In the Netherlands—a country that is home to thousands of locks, dams, and other man-made water control structures—the doorbell has been a way to balance the needs of humans and other creatures. And the project team says other countries facing similar challenges are already beginning to consider their own creative solutions.

You can keep an eye out for fish and ring the doorbell here.

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