Dutch city uses online 'fish doorbell' to help migrating fish move through locks

A unique project in Utrecht, Netherlands, is using an online "fish doorbell" to help fish navigate a river lock during their spring migration. The initiative allows people watching a livestream to alert local water authorities when fish are waiting to pass through, reports the Associated Press. An underwater camera at the Weerdsluis lock streams live footage to a website. Viewers who spot fish can press a button that sends a screenshot to organizers. Once enough fish are detected, a water worker opens the lock, allowing them to continue their journey to shallow spawning grounds. Now in its fifth year, the project has gained millions of viewers worldwide. “I guess the combination of a good cause, a beautiful story, and just a simple idea generates all this attention,” said Mark van Heukelum, the ecologist behind the concept. Without the doorbell system, fish such as bream, pike, and bass can become trapped behind the lock, making them easy targets for predators. The lock is rarely opened for boats in the spring, so the doorbell ensures the fish aren’t left waiting. Anna Nijs, an ecologist with the Utrecht municipality, was surprised by the project's global appeal. “We get a lot of fan mail from people who think it’s slow TV and they find it relaxing,” she said. “Besides, they appreciate that they can actually do something to help.” As water temperatures rise, more fish appear on the livestream, keeping viewers engaged and actively participating in conservation efforts.