Nature
PUBLISHED
Utrecht's famous fish doorbell, which first began operating in 2021, is returning for another year. Soon, people of the Internet will donate their time to help Dutch fish get breeding.
The canals of Utrecht in the Netherlands are filled with a whole host of fish, including catfish, bream, and pike. In the spring, thousands of fish make their way through the "Oudegracht" or "old canal" running through the center of the city, in search of a place to breed. But unfortunately for these randy fish, there is often a small obstacle in their way; they haven't figured out how to operate the canal locks. Weerdsluis, a manually-operated lock, is in their way.
In 2021, ecologists Mark van Heukelum and Anne Nijs were working on a biodiversity project on the canal, when they saw the lock operator open the lock to let a large group of fish to pass through.
“You have to see the Oudegracht as a motorway for fishing. Sometimes you see literally dozens of fish floundering in front of the lock gate, so a fish jam is created,” van Heukelum told Dutch news network AD, per Good News Network.
“The Weerdsluis is the link between the Vecht and the Kromme Rijn. In winter the fish swim deeper, it is warmer and safer there. In the summer they want to go to shallow water so that they can reproduce."
This wasn't just a traffic issue, as the fish were vulnerable to predators while stuck waiting for the lock to open. To avoid fish jams, they came up with a neat solution: a "fish doorbell".
The idea itself is simple and effective. An underwater webcam was placed in the canal, pointed at Weerdsluis, and livestreamed 24 hours a day to anyone who chooses to watch the show. If fish approach the lock, viewers of the webcam are tasked with alerting the lock operator by pressing a digital "doorbell". The operator receives a notification, and if enough fish are waiting at the lock, then they will manually open it to let them pass through. The only challenge to the plan was that it required volunteers who would take time out of their day to regularly check on the fish situation.
“I thought I’d reach out to the public and see how many people would be willing to do this for a few minutes per day. Initially we even went door-to-door, asking households near the lock if they were interested in helping out,” van Heukelum told the Guardian in 2023. “Little did we know that it would go viral in just a matter of days."
The project was refreshingly popular. Just like Fat Bear Week, the idea caught on with the public, who were more than happy to watch some fish action and help them get to their destination. In 2024, the livestream drew about 2.7 million viewers from around the world, all sitting there waiting to press the doorbell for these fish in need.
As well as helping fish on their way, the webcam helps ecologists learn about which species of fish are using the canals. Whilst the fish are helped by the webcam and its helpful volunteers, it goes both ways.
"[Fish] are vital to the rivers, canals, and waterways of Utrecht. They help keep the water clean and healthy, contributing to biodiversity and the liveability of our city," the fish doorbell website explains.
"So we give them something back. When fish are ready to spawn and lay eggs, we help them on their journey."
The fish doorbell will begin livestreaming on YouTube again on March 2, 2026.
