Utah Fish Doorbell Returns for Migration
Utrecht's beloved "fish doorbell" returns for migration season, allowing residents to ring a virtual bell alerting lock keepers when fish are waiting to pass through canals. This interactive city feature blends urban technology, wildlife conservation, and community engagement. The initiative demonstrates how cities can creatively involve residents in environmental stewardship while maintaining urban infrastructure.
The concept for the world's first "fish doorbell" originated in 2020 when ecologist Mark van Heukelum noticed fish congregating at the Weerdsluis lock in Utrecht. He and fellow ecologist Anne Nijs developed the idea to help these fish continue their migration, which was being blocked by the closed lock. The system operates during the spring migration season, typically from early March to late May or June. During this period, the lock is infrequently opened for boats, creating a bottleneck for fish swimming upstream to their spawning grounds in the Kromme Rijn river. This delay makes them vulnerable to predators like cormorants and grebes. When a viewer rings the virtual bell, a screenshot is sent to the lock operator. If enough fish are observed waiting, the lock keeper manually opens the gate to allow them to pass through safely. This crowdsourced monitoring has turned into a viral sensation, with the website receiving millions of visits. In 2025, the fish doorbell website recorded 30 million visits from 2.3 million unique users, and the bell was rung over 200,000 times. The project has not only helped countless fish but also provided valuable data on the urban underwater ecosystem. The underwater camera has revealed a surprising diversity of life in the canals. A total of 13 different species were spotted in 2025, including common species like perch, pike, and bream, as well as rarer sightings of eel and bleak, whose presence indicates good water quality. Even a lost koi fish has made an appearance. The project's popularity surged internationally after being featured on the HBO show *Last Week Tonight with John Oliver*. In 2025, Germany had the most users, followed by the United States and the Netherlands. The initiative is a collaboration between the Municipality of Utrecht, the De Stichtse Rijnlanden Water Board, and Mark van Heukelum's organization, Dutch Wallfish.
