The central Dutch city of Utrecht has installed a “fish doorbell” on a river lock that lets viewers of an online livestream alert authorities to fish being held up as they make their springtime migration to shallow spawning grounds. The idea is simple: an underwater camera at Utrecht’s Weerdsluis lock sends live footage to a website. When somebody watching the site sees a fish, they can click a button that sends a screenshot to organizers. When they see enough fish, they alert a water worker who opens the lock to let the fish swim through.

'Fish doorbell' in Dutch river an unlikely hit. (2025, March 20). Philippine Daily Inquirer, pp. A1, A4.