Utrecht’s ‘Fish Doorbell’ Returns to Help Spring Migration

The ‘fish doorbell’ in Utrecht is once again operational. For the sixth consecutive year, individuals can assist fish trapped near the Weerdsluis in the city center by pressing a button on their phones or computers, alerting the lock keeper to open the sluice.

The underwater camera activated at 09:00 this morning during an official opening attended by a council member and students from the Utrecht primary school De Koekoek, who unveiled a special artwork at the camera’s location. The livestream was immediately so busy that pressing the button was temporarily unavailable.

Barry the Barbel, a seven-meter-long inflatable fish, has also been deployed, standing on the Neude to raise awareness about clean water.

The ‘fish doorbell’ was conceived in 2021 by ecologist Mark van Heukelum to aid fish migrating towards the Kromme Rijn. In spring, fish attempt to spawn, but early in the year, they often discover themselves waiting behind closed sluice gates due to limited boat traffic.

The doorbell provides a solution: people can watch the underwater scene live via a webcam on the site. If they spot fish, they can press a button to alert the lock keeper to open the sluice.

Van Heukelum anticipates a high volume of ‘doorbell rings’. “Fish are guided by temperature. It’s been a mild winter, so there’s a solid chance the fish are already active and want to swim upstream.”

The system relies on a live webcam trained on the water near the Weerdsluis. When viewers observe fish congregating, they activate the ‘doorbell’ – a digital button on the website. This sends an immediate notification to the lock keeper, who then opens the sluice to allow the fish to pass. The initiative aims to mitigate the challenges fish face when navigating waterways obstructed by closed sluices, particularly during periods of low boat traffic.

According to reports, the platform experienced a surge in popularity last year, with 2.3 million viewers worldwide and 30 million visits to the site. The site was even temporarily overwhelmed by traffic.

Creator Van Heukelum welcomes the attention. He isn’t concerned about the initiative being overwhelmed by its popularity. “We receive a lot of reports, but that’s not a problem. We’ve set it up so we can quickly scroll through the photos and quickly see if You’ll see many fish waiting or if it’s always the same one.”

His advice to all those viewers around the world is: “Keep pressing. No problem, we can handle it.”